
==== Front
Sci Rep
Sci Rep
Scientific Reports
2045-2322
Nature Publishing Group UK London

39294256
72516
10.1038/s41598-024-72516-7
Article
Understanding the mechanisms behind the antibacterial activity of magnesium hydroxide nanoparticles against sulfate-reducing bacteria in sediments
http://orcid.org/0000-0003-3828-2763
Xia Dong dongx@wzu.edu.cn

Shi Xiaoyu
Chen Kai
Hao Aimin
Iseri Yasushi
https://ror.org/020hxh324 grid.412899.f 0000 0000 9117 1462 College of Life and Environmental Science, Wenzhou University, Wenzhou, 325035 Zhejiang China
18 9 2024
18 9 2024
2024
14 2183121 3 2024
9 9 2024
© The Author(s) 2024
2024
https://creativecommons.org/licenses/by-nc-nd/4.0/ Open Access This article is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which permits any non-commercial use, sharing, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if you modified the licensed material. You do not have permission under this licence to share adapted material derived from this article or parts of it. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by-nc-nd/4.0/.
Nanomaterials, with their small size, surface characteristics, and antibacterial properties, are extensively employed across environmental, energy, biomedical, agricultural, and other industries. This study examined the antibacterial efficacy of magnesium hydroxide (Mg(OH)2) nanoparticles (NPs) against sulfate-reducing bacteria (SRB) within sediments. The inhibitory effects of two types of Mg(OH)2 NPs with distinct particle sizes (20.3 and 29.6 nm) and concentrations (0–10.0 mg/mL) were examined under optimal treatment conditions. The antibacterial mechanisms of Mg(OH)2 NPs through direct contact and dissolution effects were determined. The results revealed a correlation between the concentration, particle size, and inhibitory activity, with the smallest NPs (20.3 nm) at the highest concentration (10.0 mg/mL) substantially reducing SRB counts from 8.77 ± 0.18 to 6.48 ± 0.13 log10 colony forming units/mL after 6 h treatment. Treatment with high concentrations of Mg(OH)2 NPs induced cellular damage, reduced intracellular lactate dehydrogenase activity, and elevated intracellular catalase activity and H2O2 content, suggesting that the contact effect of NPs stimulated SRB. This leads to oxidative stress response and structural damage to the cell membrane, which has emerged as the primary driver of the antibacterial action of Mg(OH)2 NPs. This study presents a novel nanomaterial that can inhibit and control SRB in natural sedimentary environments.

Keywords

Antibacterial activity
Magnesium hydroxide nanoparticle
Mechanism
Sediment
Sulfate-reducing bacteria
Subject terms

Environmental microbiology
Nanoparticles
http://dx.doi.org/10.13039/501100001809 National Natural Science Foundation of China 42007152 Xia Dong issue-copyright-statement© Springer Nature Limited 2024
==== Body
pmcIntroduction

Nanomaterials have garnered considerable attention owing to their unique surface properties and small-size effects1,2. They have been extensively applied in various industries, including environmental and energy engineering, aerospace, biomedicine, and agriculture3–7. Importantly, nanoparticles (NPs) can serve as potent antibacterial agents that frequently surpass the efficacy of traditional inorganic agents6–11.

Silver and gold NPs have demonstrated high antibacterial activity against Xanthomonas oryzae and Pyricularia oryzae12. Titanium dioxide NPs reportedly exhibit antibacterial activity against bacterial strains, including Escherichia coli and Pseudomonas aeruginosa, and fungal strains, such as Aspergillus flavus and Rhizopus oryzae, with a substantial inhibitory effect exceeding 90% on Pseudomonas solanacearum13. Tahir et al. utilized sapodilla (Manilkara zapota) for the biosynthesis of magnesium oxide NPs, which showed enhanced antibacterial activity against E. coli and Staphylococcus aureus when compared with NPs synthesized using standard methods14. Although nanomaterials exert promising antibacterial properties, concerns regarding their cost and biotoxicity persist, owing to their potential accumulation and adverse effects on organisms. Therefore, the development of novel, eco-friendly, and cost-effective antibacterial materials is crucial for ecological and environmental protection. Magnesium hydroxide (Mg(OH)2) NPs have emerged as promising inorganic materials owing to their low cost and environmentally friendly nature. They are extensively used for heavy metal adsorption, wastewater treatment, flame retardancy, and other applications15,16. Moreover, magnesium, being the second most abundant intracellular cation and an essential nutrient, can be efficiently degraded and metabolized by organisms. Additionally, excess Mg2+ and OH− can be effectively eliminated, resulting in lower antibacterial activity against organisms16,17. Alves et al. extensively explored the broad-spectrum antibacterial effects of Mg(OH)2 NPs, noting considerable activity against S. aureus, Staphylococcus epidermidis, Bacillus subtilis, and Bacillus thuringiensis at concentrations above 1000 μg/mL17. These NPs also exhibit potent antibacterial activity against E. coli16,18,19 and other pathogenic bacteria commonly found in tea blackspots20,21, confirming their reliability as antibacterial agents. Moreover, Mg(OH)2 NPs are non-toxic, maintain weak alkalinity and thermal stability, and can be easily synthesized22–24; thus, they are substantially more advantageous than other antibacterial agents in terms of both synthesis and application.

Sulfate-reducing bacteria (SRB), anaerobes present in water and sediments worldwide, influence the carbon, nitrogen, and sulfur cycles through organic matter mineralization and sulfate reduction25–29. These bacteria utilize sulfate as an electron acceptor, producing hydrogen sulfide during dissimilatory sulfate reduction under anaerobic conditions, and contribute markedly to sulfide production in sediments and overlying water30,31. Sulfate reduction in sediments has been linked to the formation of black odorous sediments and black blooms, thereby affecting water quality and ecological health32–34.

Although previous studies have primarily focused on the antibacterial activity and mechanisms underlying the action of Mg(OH)2 NPs against indicator bacteria, such as E. coli, S. aureus, and other pathogenic strains, no study has explored their effects on specific functional bacteria, such as SRB, which are commonly found in black odorous sediments. Investigating the application of Mg(OH)2 NPs in the protection of water bodies, especially in treating water and sediments from closed and eutrophic water bodies, holds notable research importance. Thus, in the present study, we aimed to address this research gap by examining the antibacterial properties of Mg(OH)2 NPs, generated through various methods, against SRB extracted from hypertrophic lake sediments. The effects of Mg(OH)2 NPs of different sizes and concentrations on SRB growth were also analyzed. Our findings provide a scientific foundation for the development of highly efficient and environmentally friendly antibacterial agents using Mg(OH)2 NPs.

Results

Characterization of Mg(OH)2 NPs

Mg(OH)2 NPs were synthesized using two different precipitants, ammonium hydroxide (NH4OH) and sodium hydroxide (NaOH), and their properties were compared. X-ray diffraction (XRD) analysis was conducted to assess the crystalline phases of NPs synthesized using NH4OH (Fig. 1a) and NaOH (Fig. 1b). The diffraction peaks corresponding to the (001), (100), (101), (102), (110), (111), (103), and (201) planes of Mg(OH)2 (JCPDF-044-1482) indicate that this was the predominant inorganic phase in both types of NPs. Additionally, several peaks of NPs synthesized using NaOH were attributed to inorganic sodium chloride (JCPDF 070-2509). Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) (Fig. 2) revealed nanoplatelet-like morphologies for both NPs synthesized using NH4OH (Fig. 2a,c) and NaOH (Fig. 2b,d). The NaOH method produced NPs with more uniform plate shapes than those generated using NH4OH, with average particle sizes of 20.3 and 29.6 nm, respectively. The close agglomeration of Mg(OH)2 NPs was evident because of the attractive forces between the particles, which might have contributed to their antibacterial activity. The crystal growth and morphology of the hydrous Mg(OH)2 influenced the surface morphology of synthesized NPs.Fig. 1 X-ray diffraction (XRD) images of Mg(OH)2 NPs prepared using different methods. (a) Forward precipitation using ammonium hydroxide. (b) Reverse precipitation using sodium hydroxide. The red arrows indicate sodium chloride peaks. NPs, nanoparticles.

Fig. 2 Scanning electron microscopy (SEM) images (a, b) and transmission electron microscopy (TEM) images (c, d) of Mg(OH)2 NPs prepared by different methods. (a, c) Forward precipitation using ammonium hydroxide. (b, d) Reverse precipitation using sodium hydroxide. NPs, nanoparticles.

The specific surface area of NPs synthesized using NH4OH was 33.028 ± 0.330 m2/g, lower than that of the NPs synthesized using NaOH (45.881 ± 0.360 m2/g). This finding indicates that NaOH, as a precipitant, promotes more effective pore formation in Mg(OH)2 than NH4OH. Surface zeta potentials were negative (− 0.588 ± 0.171 mV) for NPs synthesized with NH4OH and positive (3.513 ± 0.102 mV) for those synthesized using NaOH. Zeta potential measurements reflect the repulsion/adsorption strength between NPs, indicating the particle dispersion stability. Both types of NPs exhibited zeta potentials with absolute values below 5 mV, thereby suggesting low stability in the dispersion system, where attractive forces may exceed repulsion, leading to NP condensation.

The ultraviolet (UV)-visible absorption spectra of the Mg(OH)2 NPs displayed single excitonic peaks at 268 and 265 nm for NPs synthesized using NH4OH and NaOH, respectively (Fig. 3), and the excitonic absorption peaks confirmed the presence of Mg(OH)2 in the samples24. Figure 4 shows the Fourier-transform infrared (FT-IR) spectra of Mg(OH)2 NPs synthesized using NH4OH and NaOH. The strong and sharp peaks at 3689 and 3692 cm−1 were attributed to the O–H stretching vibration of Mg(OH)2; peaks around 1644/1131 and 1667/1107 cm−1 were due to the bending vibration of the O–H bond; and small peaks at around 652 and 643 cm−1 were attributed to the Mg–O stretching vibrations of Mg(OH)2 NPs. All observed peaks corresponded to the Mg(OH)2 crystal structure in the samples24. Peak characterization revealed that the synthesized samples were Mg(OH)2. The peaks at 1424 and 1439 cm−1 indicated the C-H bending vibration corresponding to the organic matter in the samples.Fig. 3 UV–Visible absorption spectrum of synthesized Mg(OH)2 NPs. Blue line, forward precipitation using ammonium hydroxide. Red line, reverse precipitation using sodium hydroxide. NPs, nanoparticles.

Fig. 4 FT-IR spectrum of synthesized Mg(OH)2 NPs. (1) Reverse precipitation using ammonium hydroxide. (2) Forward precipitation using sodium hydroxide. FT-IR, Fourier-transform infrared; NPs, nanoparticles.

Optimization of antibacterial properties of NPs

Treatment time

The effects of different treatment times on the SRB growth are depicted in Fig. 5a. In a period of 24 h, the bacterial count of SRB notably increased from 8.74 ± 0.09 to 9.08 ± 0.09 log10 colony forming units (CFUs)/mL in the absence of Mg(OH)2 NPs (control). Conversely, treatment with 0.5 mg/mL of Mg(OH)2 NPs gradually decreased the bacterial count of SRB from 8.78 ± 0.08 to 8.57 ± 0.08 log10 CFUs/mL within 24 h when compared with that of the control. At NP concentrations of 5.0 and 10.0 mg/mL, the bacterial count significantly decreased from 8.70 ± 0.09 to 8.68 ± 0.09 log10 CFUs/mL to 7.92 ± 0.08 and 6.48 ± 0.06 log10 CFUs//mL within 6 h, respectively (p < 0.01). The results suggest that a 6-h treatment period can achieve the best antibacterial effect of Mg(OH)2 NPs at higher concentrations. Conversely, for lower concentrations (0.5 and 1.0 mg/mL), a 24-h treatment period is recommended.Fig. 5 Mg(OH)2 NP treatments optimization on sulfate-reducing bacteria (SRB). (a) Treatment time (** p < 0.01 vs. 5 and 10 mg/mL at 0 h). (b) Treatment temperature (** p < 0.01 vs. control [0 mg/mL] at 37 °C). (c) Initial bacterial concentration (** p < 0.01 vs. control [0 mg/mL]). CFU, colony-forming unit; NPs, nanoparticles.

Treatment temperature

The optimal treatment temperature was tested within a narrow temperature range of 25–37 °C21,35 and results are depicted in Fig. 5b. In the control group, SRB exhibited the highest growth at 37 °C, with a bacterial count of 11.90 ± 0.12 log10 CFUs/mL; the lowest growth was observed at 25 °C, with a bacterial count of 11.26 ± 0.11 log10 CFUs/mL. Notably, the bacterial count decreased with increasing Mg(OH)2 NP concentrations at 37 °C. Compared with the control, treatment with 10.0 mg/mL Mg(OH)2 NPs significantly reduced the bacterial count to 9.70 ± 0.10 log10 CFUs/mL (p < 0.01). However, there was no significant difference in bacterial count at concentrations of 1.0, 2.5, 5.0, and 10.0 mg/mL at 25 or 30 °C. Thus, 37 °C was identified as the optimal treatment temperature.

Initial SRB concentration

The effect of different initial bacterial concentrations on SRB growth is shown in Fig. 5c. At initial SRB concentrations of 106 and 108 CFUs/mL, the bacterial count notably decreased from 6.77 ± 0.07 to 8.90 ± 0.09 log10 CFUs/mL to 4.48 ± 0.04 and 6.70 ± 0.07 log10 CFUs/mL, respectively, with increasing NP concentrations. Although the bacterial count also decreased at an initial concentration of 1011 CFUs/mL, the bacterial viability was relatively higher than that at an initial concentration of 106–108 CFUs/mL, with increasing NP concentrations; this finding suggests that an initial SRB concentration of 106–108 CFUs/mL was appropriate.

Based on these results, the following treatment conditions were selected for subsequent experiments: treatment time, 6 h; treatment temperature, 37 °C; and initial inoculation concentration of SRB, 106–108 CFUs/mL.

Antibacterial activity of synthesized NPs

Different NP sizes

The bacterial counts of SRB gradually decreased upon treatment with increasing concentrations of Mg(OH)2 NPs of different sizes (Fig. 6a). At concentrations of 0.5, 1.0, and 2.5 mg/mL, 20.3 nm NPs resulted in higher bacterial counts (8.70 ± 0.17, 8.65 ± 0.16, and 8.31 ± 0.17 log10 CFUs/mL, respectively) than 29.6 nm NPs (8.65 ± 0.17, 8.60 ± 0.16, and 8.30 ± 0.17 log10 CFUs/mL, respectively). However, at higher concentrations of 5.0 and 10.0 mg/mL, 20.3 nm NPs resulted in significantly lower bacterial counts (7.92 ± 0.16 and 6.48 ± 0.13 log10 CFUs/mL, respectively) than 29.6 nm NPs (8.13 ± 0.16 and 7.95 ± 0.16 log10 CFUs/mL, respectively) (p < 0.05). Hence, smaller and larger NPs exerted strong antibacterial effects at higher and lower concentrations, respectively. Based on this finding, Mg(OH)2 NP size of 20.3 nm was selected for subsequent experiment of Antibacterial mechanism of NPs.Fig. 6 Bacterial count of sulfate-reducing bacteria (SRB) treated with Mg(OH)2 NPs at different particle sizes and concentrations. (a) Different particle sizes (20 nm corresponds to 20.3 nm; 30 nm corresponds to 29.6 nm [* p < 0.05, 20 nm vs. 30 nm]). (b) Different concentrations (* p < 0.05, ** p < 0.01 vs. control [0 mg/mL]). NPs, nanoparticles.

Different NP concentrations

Figure 6b presents the SRB count after treatment with different concentrations of Mg(OH)2 NPs. Treatment with 20.3 and 29.6 nm NPs gradually decreased the bacterial count from 8.77 ± 0.18 to 8.74 ± 0.17 log10 CFUs/mL to 6.48 ± 0.13 and 7.95 ± 0.16 log10 CFUs/mL, respectively, with increasing NP concentrations. At concentrations of 2.5, 5.0, and 10.0 mg/mL, 20.3 and 29.6 nm NPs significantly reduced the bacterial count compared with the control (p < 0.05). Notably, treatment with 20.3 nm NPs at 10 mg/mL resulted in a lowest bacterial count (6.48 ± 0.13 log10 CFUs/mL) with minimal colony growth (Supplementary Fig. 1), indicating a relatively stronger antibacterial effect at higher concentrations.

Antibacterial mechanism of NPs

SRB growth

To further determine the antibacterial activity of Mg(OH)2 NPs, in addition to the plate colony counting test (Fig. 6b), we employed the Cell Counting Kit-8 (CCK-8) assay with high sensitivity to evaluate the viability of SRB at different concentrations of Mg(OH)2 NP and Mg2+ from the cellular level. Results from the CCK-8 assay (Fig. 7a,b; Supplementary Fig. 2) revealed an obvious decrease in bacterial cell viability after 6 h of exposure to Mg(OH)2 NPs, which gradually decreased with increasing treatment duration, and the lowest bacterial cell viability was observed at 10 mg/mL (Fig. 7a). A dose-dependent effect was observed upon treatment with Mg2+, and bacterial cell viability remained 26.8 ± 0.7% at 2.5, 5, and 10 mg/mL, which was higher than that observed upon treatment with Mg(OH)2 NPs (Fig. 7b).Fig. 7 Bacterial cell viability assay using Cell Counting Kit-8 at different Mg(OH)2 NP concentrations (a) and Mg2+ concentrations (b). NPs, nanoparticles.

Both the control and Mg(OH)2 NP treatment significantly increased the intracellular total protein (TP) content after 6 h (p < 0.01; Fig. 8a), with the Mg(OH)2 NP treatment resulting in a significantly lower increase than the control (p < 0.01). Although the TP content increased with time in both groups, the increase was notably lower in the NP treatment group, suggesting that Mg(OH)2 NPs suppressed intracellular protein synthesis. Conversely, treatment with Mg2+ did not significantly alter the TP content at any concentration after 6 h (p > 0.05; Fig. 8b).Fig. 8 Intracellular total protein content at different Mg(OH)2 NP (a) and Mg2+ concentrations (b) (** p < 0.01 vs. control [0 mg/mL at 6 h]). NP, nanoparticle.

Cell membrane permeability

Lactate dehydrogenase (LDH) serves as an index of cell membrane permeability. After 6 h of treatment, different Mg(OH)2 NP concentrations significantly decreased the intracellular LDH activity (p < 0.05), which was significantly lower than that of the blank control (p < 0.01; Fig. 9a). Conversely, treatments with varying NP concentrations significantly increased the extracellular LDH activity (p < 0.01; Fig. 9b), indicating that cell membrane permeability increased with increasing NP concentrations. Considering treatment with Mg2+, no significant difference was observed between intracellular and extracellular LDH activities with treatment time (p > 0.05), with both decreasing significantly after 6 h at 10 mg/mL (p < 0.01; Fig. 9c,d).Fig. 9 Lactate dehydrogenase (LDH) intra/extracellular activity at different Mg(OH)2 NP (a, b) and Mg2+ concentrations (c, d) (** p < 0.01 vs. control [0 mg/mL at 6 h]). NP, nanoparticle.

Oxidative stress

Six hours of treatment with Mg(OH)2 NPs significantly increased (p < 0.01) the level of H2O2, an important reactive oxygen species (ROS) that can damage the cell membrane and oxidize intracellular nucleic acids and proteins. However, no significant differences were observed with increasing Mg2+ concentrations (p > 0.05; Fig. 10), except for a significant increase in H2O2 content at 0.5 mg/mL Mg2+ (p < 0.05). Notably, although increasing NP concentrations decreased the H2O2 content, treatment with Mg(OH)2 NP resulted in a higher H2O2 content than treatment with Mg2+ (p < 0.05). Correlation analysis demonstrated a significant positive correlation between H2O2 content and intracellular catalase (CAT) activity at NP concentrations of 0.5, 1.0, 2.5, and 10.0 mg/mL (R0.5 = 0.845, R1.0 = 0.882, R2.5 = 0.930, and R10.0 = 0.816, respectively; p < 0.05) and extracellular LDH activity (R = 0.467, p < 0.01), indicating NP-induced bacterial oxidative stress reactions.Fig. 10 Catalase (CAT) intracellular activity at different Mg(OH)2 NP (a) and Mg2+ concentrations (b) (** p < 0.01 vs. control [0 mg/mL at 6 h]). NP, nanoparticle.

In cells treated with different Mg(OH)2 NP concentrations, the intracellular activity of CAT, an enzyme essential for removing excess H2O2 and preventing oxidative stress damage, was increased and significantly higher than that in the control after 6 h (p < 0.01). In particular, at 1.0 mg/mL NP, the intracellular CAT activity was approximately four times higher than that of the control (Fig. 11a). Correlation analysis revealed a significant negative correlation between intracellular CAT and LDH activity in Mg(OH)2 NP-treated cells (R =  − 0.349, p < 0.05), indicating that NPs induced bacterial oxidative stress reactions and impacted SRB cell permeability. After 6 h of Mg2+ treatment, there were no significant differences in intracellular CAT activity with treatment time (p > 0.05) or different concentrations when compared with the blank control (p > 0.05; Fig. 11b).Fig. 11 Intracellular H2O2 content at different Mg(OH)2 NP (a) and Mg2+ concentrations (b) (** p < 0.01 vs. control [0 mg/mL at 6 h]). NP, nanoparticle.

Energy metabolism

Treatment with different concentrations of Mg(OH)2 NPs for increasing treatment time could significantly decrease (p < 0.01) the activity of Na+/K+-ATP, an essential intracellular protein involved in regulating osmotic pressure and energy conversion, and this activity was significantly lower than that of the control after 6 h of treatment (p < 0.01; Fig. 12a). Notably, at a concentration of 10.0 mg/mL, Na+/K+-ATP activity decreased significantly to 12% of the control level. Conversely, no significant differences were observed in the intracellular Na+/K+-ATP activity with increasing treatment time at different Mg2+ concentrations (p > 0.05; Fig. 12b).Fig. 12 Na+/K+-ATP activity at different Mg(OH)2 NP (a) and Mg2+ concentrations (b) (** p < 0.01 vs. control [0 mg/mL at 6 h]). NP, nanoparticle.

Contact effect of NPs

Upon examining the surface morphology and structure of bacterial cells using SEM (Fig. 13), the untreated SRB appeared rod-like and regular in shape, with smooth surfaces and complete structures (Fig. 13a). However, after treatment with 0.5 mg/mL NPs, although their rod-like shape remained relatively intact, the bacterial cells exhibited surface holes (Fig. 13b). With increasing NP concentrations (1.0, 2.5, and 5.0 mg/mL), the number and size of the holes increased, and attachment to the bacterial surface suggested cell content leakage. The cell wall exhibited severe damage, with atrophy and substantial adhesion between cells (Fig. 13c–e). Following treatment with 10.0 mg/mL Mg(OH)2 NPs for 6 h, the bacterial cells exhibited fragmentation or concavity, losing their uniform rod-like shape with agglomerated NPs attached to them. The cell walls remained largely intact, suggesting a higher probability of NP contact with each other, forming agglomerations with increasing NP concentrations (Fig. 13f).Fig. 13 Scanning electron microscopy (SEM) images of the sulfate-reducing bacteria (SRB) cell morphology induced by Mg(OH)2 NPs. Mg(OH)2 NP concentrations (a) 0 mg/mL, (b) 0.5 mg/mL, (c) 1.0 mg/mL, (d) 2.5 mg/mL, (e) 5.0 mg/mL, and (f) 10.0 mg/mL. NP, nanoparticle.

Dissolution effect of NPs

Figure 10 illustrates the concentrations of intracellular and extracellular dissolved Mg2+ ions in SRB treated with different concentrations of Mg(OH)2 NPs. Intracellular concentrations of dissolved Mg2+ ions significantly increased after 6 h of treatment (p < 0.01) but decreased significantly with increasing NP concentration (p < 0.01; Fig. 14a). Treatment with Mg(OH)2 NPs resulted in markedly higher extracellular Mg2+ concentrations than the control after 6 h (p < 0.01; Fig. 14b) and these concentrations increased with increasing NP concentration. The concentrations of extracellular dissolved Mg2+ induced by NP treatment was significantly and negatively correlated with intracellular TP content and Na+/K+-ATP activity of SRB (R =  − 0.704, p < 0.01; R =  − 0.772, p < 0.01, respectively). This suggests an increased release of Mg2+ ions at higher Mg(OH)2 NP concentrations, leading to a large loss of intracellular Mg2+ ions and exerting negative effects on intracellular protein synthesis and energy metabolism in the SRB.Fig. 14 Dissolved Mg2+ concentration in Mg(OH)2 NPs at different treatment concentrations. (a) Intracellular. (b) Extracellular (** p < 0.01 vs. control [0 mg/mL at 6 h]). NP, nanoparticle.

Based on the above results, the properties and contact effect of the NPs could be the main factors contributing to the antibacterial activity of Mg(OH)2 NPs rather than the effect of Mg2+. NPs accumulate on the bacterial surface, induce bacterial oxidative stress and ion channel dysfunction, and increase cell membrane permeability and the release of intracellular Mg2+, which negatively affects the synthesis of intracellular proteins and energy and inhibits intracellular energy metabolism in SRB (Fig. 15).Fig. 15 Schematic diagram of the mechanism underlying the antibacterial activity of Mg(OH)2 NPs. NPs, nanoparticles.

Discussion

The precipitant properties can substantially impact the surface area of metal hydroxides. Previous comparisons between NH4OH and NaOH revealed that sodium ions were introduced into the reaction mixture, affecting the surface properties of the Mg(OH)26. In the present study, the Mg(OH)2 NPs synthesized using NaOH also contained sodium ions; however, they exhibited a more regular morphology, smaller particle size, and better surface properties than those synthesized using NH4OH. This property of the Mg(OH)2 NPs synthesized using NaOH can be attributed to the reverse precipitation method, which maintains a stable alkaline environment during NP synthesis. Higher pH values can promote crystal growth and nucleation of Mg(OH)2, thereby increasing its surface area36. Likewise, Mohammadi and Ghasemi (2018) observed NP size reduction at higher pH values, which aligns with our findings37. The absorption peaks of the Mg(OH)2 NPs synthesized using NaOH were slightly shifted as compared to those synthesized using NH4OH. This shift might be due to the quantum size effect, which could be responsible for the orderly shift in the absorption edge toward shorter wavelengths as the NPs decrease in size24. These results highlight the variations in the physical and chemical properties of Mg(OH)2 NPs with different precipitants, precursors, and synthesis methods. Precipitants and precursors can markedly influence the surface properties of metal oxides and metal hydroxide NPs, with NH4OH and NaOH identified as ideal precipitants and magnesium sulfate and magnesium chloride as optimal precursors1,6. Moreover, this study confirms the direct relationship between the antibacterial activity of NPs and their physical and chemical properties.

Mg(OH)2 NPs exhibit broad-spectrum antibacterial properties, demonstrating strong efficiency against both gram-negative (e.g., E. coli) and gram-positive (e.g., S. aureus) bacteria and demonstrating their potential as effective antibacterial agents15,18,19. The size and concentration of the Mg(OH)2 NPs play pivotal roles in determining their antibacterial activities. Furthermore, variations in antibacterial effects are closely linked to treatment-specific parameters, such as NP charge, surface area, and other physical and chemical properties. High concentrations of NPs can exert antibacterial effects within relatively short durations than that exerted by the lower concentration of NPs (bacteria: 2–10 h; fungi: < 3 days)38. Chen et al.39 confirmed that Mg(OH)2 NPs effectively inhibit the growth of tea fungi. The inhibition rate of 5 mg/mL Mg(OH)2 NPs on mycelial growth was 48.78% in 3 days, and the inhibition rate of 50 mg/mL Mg(OH)2 NPs treatment was 100%; these findings imply that the inhibition rate increased with the concentration of Mg(OH)2 NPs. In the present study, we observed a similar antibacterial effect against SRB; Mg(OH)2 NPs damaged the cell wall and cell membrane of SRB, leading to the leakage of intracellular substance and bacterial cell inactivation. However, the effective antibacterial effect was only observed at relatively high NP concentrations (10.0 mg/mL) and high temperature (37 °C) suitable for SRB growth. Furthermore, the size of NP agglomerates increases with increasing particle concentration and treatment duration, leading to diminished antibacterial activity8–10,40–44, and this was consistently observed in the current study. Upon treatment with 10.0 mg/mL NPs, SRB maintained their rod-like shape with improved surface integrity, possibly because of NP agglomeration in aqueous solutions at high particle density, whereas an increase in agglomerate size reduced the contact effect of NPs (Supplementary Fig. 3)9,38. Mg(OH)2 NPs synthesized using both methods exhibited inhibitory activity against SRB, accompanied by substantial differences in their antibacterial properties, underscoring the importance of considering synthesis methods and NP physicochemical properties when selecting efficient antibacterial agents.

Previous research has highlighted the toxic impact of NPs45, such as ZnO NPs, on cells, impairing mitochondrial function and triggering apoptotic cell death45,46, potentially inhibiting cell survival and proliferation through apoptosis induction. In this study, the synthesized Mg(OH)2 NPs demonstrated robust surface adsorption capabilities, rapid attachment to bacterial surfaces, impairment of bacterial cell walls, and disruption of normal physiological metabolism. This phenomenon may be attributed to the stable high concentration of peroxide ions on the Mg(OH)2 NP surfaces, contributing to their antibacterial effect15. Furthermore, previous studies have suggested that hydroxide ions (OH−) and Mg2+ in a magnesium hydroxide suspension do not interact with the antibacterial effects of Mg(OH)2 NPs15,17,47. In the present study, although Mg2+ treatment served as a positive control, it did not exert any discernible effects on bacterial metabolism and oxidative stress, indicating that Mg2+ does not contribute to the antibacterial activity of Mg(OH)2 NPs.

The inhibition of bacterial protein synthesis or intracellular protein leakage through damaged cell membranes can disrupt normal bacterial metabolism and lead to bacterial death48–50. Research on the antibacterial properties and mechanisms of action of nanomaterials, such as zinc oxide or zinc phosphate NPs42,50, has revealed that these NPs can be adsorbed onto bacterial surfaces, physically damage the cell wall and membrane, and increase cell membrane permeability, thereby allowing free zinc ions to enter the cells. These ions generate ROS, damage intracellular proteins and lipids, inactivate proteins, and disrupt bacterial metabolism and activities51,52. In the present study, treatment with increasing Mg(OH)2 NP concentrations severely damaged the cell wall and membrane of SRB, while the intracellular TP content substantially increased without notable changes in the extracellular TP content (Supplementary Fig. 4). This result suggests a limited flow of intracellular proteins into the extracellular medium, possibly due to the Mg2+ ions produced by the dissolution of the Mg(OH)2 NPs, which are crucial for enhancing intracellular protein synthesis.

LDH is a cytoplasmic enzyme vital for glycolysis and gluconeogenesis53. When cell necrosis or apoptosis occurs, the structure of the cell membrane is damaged, and LDH is released into the culture medium. Thus, cytotoxicity can be quantified by measuring intracellular and extracellular LDH activities. The findings of the present study indicate that the SRB cell wall and membrane were damaged, and the permeability of the bacterial cell membrane increased considerably at higher concentrations of Mg(OH)2 NPs. This result aligns with the results of a study on the antibacterial activity of titanium oxide NPs, in which the extracellular LDH activity increased with the NP concentration40. In a study exploring the antibacterial activity of ZnO NPs, the addition of NPs markedly enhanced ROS production induced by higher concentrations and longer treatment times, indicating enhanced bacterial oxidative stress with increased NP concentration38. In the present study, the notable negative correlation between intracellular LDH and CAT activity suggested that the enhanced cell membrane permeability could be attributed to NP-induced oxidative stress reactions in SRB, whereas the positive correlation between CAT activity and H2O2 content indicated that NP-induced oxidative stress in SRB was due to H2O2 production. Na+/K+-ATP provides cellular energy by catalyzing adenosine triphosphate hydrolysis, facilitating the transport of sodium and potassium ions across the cell membrane, and regulating cell osmotic pressure, ion balance, and other physiological activities54. The observed decrease in intracellular Na+/K+-ATP activity with increasing NP concentration suggests that Mg(OH)2 NPs can impair cell membrane integrity and fluidity in SRB, affecting energy metabolism and osmotic pressure balance, ultimately slowing bacterial growth and causing cell rupture. Compared with the Mg(OH)2 NP treatments, Mg2+ did not induce significant differences in LDH, CAT, and Na+/K+-ATP activities with increasing treatment time at different concentrations, and there were no significant correlations among them, further demonstrating that Mg2+ does not contribute to the antibacterial activity of the Mg(OH)2 NPs.

In future experiments, we plan to employ TEM to observe Mg(OH)2 NP distribution within bacterial cells and directly measure the contact effects of the NPs. Additionally, we will measure ROS levels to directly analyze the oxidative damage caused by Mg(OH)2 NPs in bacterial cells.

Conclusions

In this study, we employed simple precipitation methods to synthesize plate-like Mg(OH)2 NPs, with a small size and large volume-to-surface ratios. Combining a magnesium chloride precursor with a digestion temperature of 80 °C for 2 h yielded 29.6 and 20.3 nm Mg(OH)2 NPs using NH4OH and NaOH as precipitants, respectively. SEM confirmed that the synthesized NPs exhibited an agglomerated plate-like morphology.

The antibacterial activity of NPs was evaluated against SRB extracted from the shore sediments of Lake Taihu. Notably, a higher antibacterial efficacy was observed at higher concentrations of NPs with smaller particle sizes. At relatively high concentrations (10 mg/mL), the NPs exhibited effective antibacterial activity against SRB growth. Mechanistic analysis revealed that the properties and concentration of NPs significantly influenced the antibacterial activity, with the contact effect playing a pivotal role. The properties and contact effect of NPs are the main factors contributing to the antibacterial activity of Mg(OH)2 NPs. Contact between NPs and SRB cell membrane induces oxidative stress, damages cell membrane integrity, increases cell membrane permeability, affects the synthesis of intracellular proteins and energy, and inhibits intracellular energy metabolism in SRB. Thus, this study underscores an economical approach for Mg(OH)2 NP synthesis using cost-effective raw materials and lays the groundwork for assessing their biological impact on SRB. Future research should explore the antibacterial activity of Mg(OH)2 NPs using various synthesis methods and particle morphologies to address issues such as NP agglomeration and the inconsistent antibacterial efficacy observed in this study.

Materials and methods

Sediment sampling

Sediment samples (0–15 cm depth) were collected from a site on the north side of the hypertrophic Lake Taihu, Jiangsu, China (31° 10′ N, 120° 24′ E) in September 2021. The characteristics of the collected sediment were as follows: pH 7.18 ± 0.05, oxidation–reduction potential − 146.9 ± 11.8 mV, total organic matter 44.13 ± 77.61 mg/g, and acid volatile sulfide 15.60 ± 1.51 mg/kg. The sediment samples were collected using sterile shovels, sealed in sterile plastic bags to prevent air oxidation, and stored in a cooler box in the field. Once transported to the laboratory, the sediment samples were stored at 4 °C before further analysis.

Enrichment and cultivation of SRB

The anaerobic enrichment and routine culture of SRB from sediments were performed at 37 °C on modified Postgate C medium55,56 containing 1.0 g/L NH4Cl, 1.0 g/L MgSO4·7H2O, 0.5 g/L K2HPO4, 0.5 g/L Na2SO4, 0.1 g/L CaCl2, 5 mL 70% sodium lactate, and 0.5 g/L yeast extract at a pH of 7.0. After high-temperature sterilization, the medium was supplemented with 5.0 g/L filter-sterilized ascorbic acid (vitamin C) and 25 g/L ammonium iron (III) sulfate (NH4Fe(SO4)2). Sediment (10 g) was added to Erlenmeyer flasks (100 mL) containing sterilized water, which were then sealed with rubber stoppers and shaken on a rotary shaker at 30 °C and 150 rpm for 24 h. The sediment suspensions were then centrifuged (3000 rpm for 5 min), and the supernatant was transferred to new sterilized flasks containing modified Postgate C medium and incubated at 37 °C and 150 rpm. After 7 days of incubation, black coloration was observed in all flasks, indicating the presence of SRB, which induced the production of metal sulfides in all enriched cultures. After standing for 30 min without agitation, the flasks were inoculated with 10% (v/v) of the supernatant in fresh Postgate medium (90% v/v) without iron (III) and incubated again under the same conditions. After three or four identical subculture stages, SRB were obtained from the cultures for analysis.

Mg(OH)2 NP synthesis

Two types of precipitants, NH4OH and NaOH, were used to synthesize Mg(OH)2 NPs and to evaluate the impact of the precipitant composition on NP characteristics.

Forward precipitation with NH4OH15,24

In this approach, 101.5 g magnesium chloride (MgCl2·6H2O, AR, ≥ 8.0%) and 3.05 g (3% of the mass of MgCl2) dispersant PEG1500 (AR) were dissolved into 1000 mL ethanol/deionized water (v/v = 1/4) to prepare the magnesium precursor solution (0.5 mol/L MgCl2 solution with 3% PEG1500), and the solution was stirred at 25 °C. Subsequently, 12 mL NH4OH (AR, 25.0–28.0%) was slowly added dropwise into the solution (yielding a concentration ratio of OH− to Mg2+ of 2:1) and continuously stirred at 80 °C for 120 min until the precipitation reaction was completed. The solution was cooled and then refrigerated at 4 °C for 24 h. The suspension of Mg(OH)2 NPs was then centrifuged at 7000 rpm for 5 min at 4 °C, the supernatant was discarded, and the precipitated Mg(OH)2 NPs were collected and washed with deionized water by centrifuging thrice to eliminate any anions and cations. Finally, Mg(OH)2 NPs were obtained after drying in a hot air oven at 80 °C for 12 h.

Reverse precipitation with NaOH47,57

In this approach, 101.5 g MgCl2∙6H2O with 3.05 g PEG1500 was dissolved into 100 mL ethanol/deionized water (v/v = 1/4), and 40 g NaOH (AR, ≥ 96.0%) was dissolved into another 900 mL volume of ethanol/deionized water. The Mg precursor solution was then slowly added to the NaOH solution to achieve a final concentration of 1.0 mol/L NaOH and continuously stirred until precipitation was completed. NPs were then obtained following the same steps as those used for forward precipitation.

Mg(OH)2 NP characterization

NP crystallinity was examined by performing XRD using a D8 Advance X diffractometer (Bruker, Billerica, MA, USA) with a copper radiation source (Cu Kα, λ = 1.5406 Å) and a secondary monochromator operating at 40 kV and 40 mA. The NP surface morphology was characterized using field-emission ultrahigh-resolution SEM (SU8600, Hitachi, Tokyo, Japan) and TEM (Tecnai™ G2 F30; FEI, Hillsboro, OR, USA). The specific surface area of NPs was determined using the Brunauer–Emmett–Teller method with a Surface Area and Porosity System (TriStar II 3020; Micromeritics, Norcross, GA, USA). Zeta potential was analyzed by electrophoretic light scattering using a Zetasizer system (Zetasizer Nano ZS90, Malvern Panalytical, Malvern, UK). The vibrational analysis of the synthesized NPs was conducted using an FT-IR spectrometer (Shimadzu IRAffinity-1S, Shimadzu, Tokyo, Japan) in the wavenumber region of 4000–600 cm−1. The adsorption of synthesized NPs was recorded in the wavelength range of 200–800 nm using a UV–visible spectrophotometer (Shimadzu UV3600, Shimadzu).

Optimal antibacterial condition tests of Mg(OH)2 NPs

Treatment time

A suspension comprising an initial SRB concentration of 108 cells/mL in a modified Postgate C medium was prepared based on the optical density. The bacterial suspensions were sealed and cultured in a shaking incubator at 37 °C and 150 rpm. For CFU determination, 100 μL of bacterial suspension was transferred after incubation for 0, 6, 18, and 24 h.

Treatment temperature

Given that the optimum growth temperature for most SRB ranges between 28 and 30 °C, the optimal temperature for moderate temperature-resistant SRB can rise to 40 °C, and the optimal temperature for effectively eliminating heavy metals is approximately 37 °C21,35. Therefore, in the present study, temperatures of 25, 30, and 37 °C were selected to identify the optimal treatment temperature. Owing to the instability of bacterial growth at a low temperature (25 °C), the initial SRB concentration was uniformly increased in this temperature optimization experiment. Bacterial suspensions with a 1011 cells/mL initial concentration were sealed and cultured for 24 h in a shaking incubator at predetermined temperatures.

Initial concentration of SRB

Initial SRB concentrations of 104, 106, 108, and 1011 CFUs/mL were used to determine the optimal initial concentrations. Bacterial suspensions were sealed and cultured at different initial concentrations for 24 h in a shaking incubator at 37 °C and 150 rpm.

These experiments were independently performed in triplicate. For CFU determination, 100 μL of bacterial suspension was transferred and diluted serially in phosphate-buffered saline (PBS) solution and plated onto agar plates (Postgate medium with 1.5% agar). These plates were sealed and incubated at 37 °C for 24 h, and CFUs were then counted. The bacterial count was expressed as log10 CFUs/mL.

Antibacterial activity testing of Mg(OH)2 NPs

SRB bacterial suspensions at an initial concentration of 108 cells/mL were cultured with 20.3 and 29.6-nm NP suspensions (0, 0.5, 1.0, 2.5, 5.0, and 10.0 mg/mL, respectively) for 6 h in a shaking incubator. Then, 100 μL of bacterial suspension was transferred and diluted serially in PBS solution and plated onto agar plates (Postgate medium with 1.5% agar) for CFU determination. The plates were sealed and incubated at 37 °C for 24 h, and CFUs were counted and expressed as log10 CFUs/mL.

Antibacterial mechanism of Mg(OH)2 NPs

SRB bacterial suspensions at an initial concentration of 108 cells/mL were cultured with 20.3-nm NP suspensions (0, 0.5, 1.0, 2.5, 5.0, and 10.0 mg/mL, respectively) for 6 h in a shaking incubator at 37 °C and 150 rpm. The same bacteria cultured without NPs were used as the controls. Bacteria cultured with Mg ions (prepared using MgCl2) at the same concentrations were used as positive controls. Three independent experiments were performed for each concentration of NPs and Mg2+. The bacterial cells were then collected by centrifugation, washed thrice using PBS, fixed in 2.5% glutaraldehyde (Electron Microscopy Sciences, Hatfield, PA, USA), and allowed to stand at 4 °C overnight. These samples were viewed using SEM, and images were captured at a magnification of 5000–100,000 × . The intracellular and extracellular magnesium ion contents were analyzed to investigate the dissolution effect of Mg(OH)2 NPs. The bacterial cultures were centrifuged at 4 °C and 8000 rpm for 10 min, and the supernatant and the bacterial cell pellet were predigested using HNO3 and subsequently analyzed using inductively coupled plasma-optical emission spectrometry (ICP-OES; Thermo ICP-OES 7200, Thermo Fisher Scientific, Waltham, MA, USA) to determine extracellular and intracellular magnesium content.

Bacterial cell viability after Mg(OH)2 NPs and Mg2+ treatments was assessed using a CCK-8 reagent kit (Merck, Burlington, MA, USA). Bacterial cell cultures treated with different concentrations of Mg(OH)2 NPs and Mg2+ were seeded in 96-well plates at a density of 1 × 104 cells per well. After adding 10 µL of CCK-8 solution, the plates were incubated in the dark for 1 h at 37 °C, and absorbance was measured at 450 nm using a microplate reader (Agilent, Santa Clara, CA, USA). Each experiment was independently performed in triplicate.

The functional enzyme activities of SRB associated with metabolism and oxidative stress, including TP, LDH, Na+/K+-ATP, and CAT, as well as the H2O2 content, were analyzed before the experiment (0 h) and after completing the experiment (6 h). The bacterial cells were collected by centrifugation at 8000 rpm for 10 min at 4 °C, resuspended in 0.85% NaCl solution, and immediately homogenized using a homogenizer. The suspension was centrifuged at 8000 rpm for 10 min at 4 °C, and the supernatant was collected and maintained on ice until measurements were conducted. The activities of intracellular and extracellular LDH were assessed using an LDH assay kit (Solarbio, Beijing, China)58,59. Considering the underlying principle of the assay, LDH catalyzes NAD+ to oxidize lactic acid to pyruvic acid, which further reacts to form products that are brown–red in an alkaline solution, and the color depth is proportional to the concentration of pyruvate. The supernatant samples were quantified using a microplate reader with a specific absorbance at 450 nm, according to the kit protocol. The contents of intracellular protein and hydrogen peroxide in the bacterial cells were determined using the Bradford protein assay kit and H2O2 content assay kit (Solarbio), following the manufacturer’s protocols. A Na+/K+-ATPase assay kit (Solarbio), based on the molybdenum blue method (measuring the absorbance of samples at 660 nm according to the kit protocol), was used to measure intracellular ATPase activity59. The intracellular CAT activity was assessed using a CAT assay kit (Solarbio); this method is based on the reaction of the enzyme with methanol in the presence of an optimal concentration of hydrogen peroxide58.

Statistical analyses

The functional enzyme activity and magnesium ion content results are presented as mean ± standard deviation (three independent experiments with three replicates for each experiment). Tests for statistically significant differences and correlation analyses were performed using SPSS version 23.0 (IBM, Armonk, NY, USA). Correlation analysis was performed to assess the relationship between SRB viability, functional enzyme activity, and intra- and extracellular Mg2+ contents. Differences were analyzed using one-way analysis of variance, and p ≤ 0.05 was considered significant.

Supplementary Information

Supplementary Figure 1.

Supplementary Figure 2.

Supplementary Figure 3.

Supplementary Figure 4.

Supplementary Information

The online version contains supplementary material available at 10.1038/s41598-024-72516-7.

Acknowledgements

We express our thanks to Ms. Hanbin Zhao, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences for cordial support.

Author contributions

D.X. designed the experiment, carried out experiments, analyzed the data, wrote and reviewed the manuscript; X.S. and K.C. assisted in the experiment and data analysis; A.H. and Y.I. supervised the experimental work. All authors reviewed and approved the final version of the manuscript.

Funding

This work was supported by the National Natural Science Foundation of China (Grant number 42007152).

Data availability

The data generated or analyzed during this study are included in this published article and its supplementary files.

Competing interests

The authors declare no competing interests.

Publisher's note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
==== Refs
References

1. Zhang D Inhibitory effect of nano-Mg(OH)2 with different morphology on pathogen Mango Phoma leaf spot J. Agric. Sci. Technol. 2022 24 140 147
Zhang, D. et al. Inhibitory effect of nano-Mg(OH)2 with different morphology on pathogen Mango Phoma leaf spot. J. Agric. Sci. Technol. 24, 140–147 (2022).
2. Chen X Liu Y Wang B Liu X Lu C Understanding role of microstructures of nanomaterials in electrochemiluminescence properties and their applications TrAC Trends Anal. Chem. 2023 162 117030 10.1016/j.trac.2023.117030
Chen, X., Liu, Y., Wang, B., Liu, X. & Lu, C. Understanding role of microstructures of nanomaterials in electrochemiluminescence properties and their applications. TrAC Trends Anal. Chem. 162, 117030 (2023).
3. Dizaj SM Lotfipour F Barzegar-Jalali M Zarrintan MH Adibkia K Antimicrobial activity of the metals and metal oxide nanoparticles Mater. Sci. Eng. C Mater. Biol. Appl. 2014 44 278 284 10.1016/j.msec.2014.08.031 25280707
Dizaj, S. M., Lotfipour, F., Barzegar-Jalali, M., Zarrintan, M. H. & Adibkia, K. Antimicrobial activity of the metals and metal oxide nanoparticles. Mater. Sci. Eng. C Mater. Biol. Appl. 44, 278–284 (2014).25280707
4. Zhang X Effect of zinc oxide nanoparticles on nitrogen removal, microbial activity and microbial community of CANON process in a membrane bioreactor Bioresour. Technol. 2017 243 93 99 10.1016/j.biortech.2017.06.052 28668561
Zhang, X. et al. Effect of zinc oxide nanoparticles on nitrogen removal, microbial activity and microbial community of CANON process in a membrane bioreactor. Bioresour. Technol. 243, 93–99 (2017).28668561
5. Deshmukh SP Patil SM Mullani SB Delekar SD Silver nanoparticles as an effective disinfectant: A review Mater. Sci. Eng. C Mater. Biol. Appl. 2019 97 954 965 10.1016/j.msec.2018.12.102 30678983
Deshmukh, S. P., Patil, S. M., Mullani, S. B. & Delekar, S. D. Silver nanoparticles as an effective disinfectant: A review. Mater. Sci. Eng. C Mater. Biol. Appl. 97, 954–965 (2019).30678983
6. Rajagopalachar S Pattar J Mulla S Synthesis and characterization of plate like high surface area MgO nanoparticles for their antibacterial activity against Bacillus cereus (MTCC 430) and Pseudomonas aeruginosa (MTCC 424) bacterias Inorg. Chem. Commun. 2022 144 109907 10.1016/j.inoche.2022.109907
Rajagopalachar, S., Pattar, J. & Mulla, S. Synthesis and characterization of plate like high surface area MgO nanoparticles for their antibacterial activity against Bacillus cereus (MTCC 430) and Pseudomonas aeruginosa (MTCC 424) bacterias. Inorg. Chem. Commun. 144, 109907 (2022).
7. Xu J Effects of silver nanoparticles on denitrification and anammox in sediments of hypertrophic and mesotrophic lakes Sci. Total Environ. 2023 858 159933 10.1016/j.scitotenv.2022.159933 36343817
Xu, J. et al. Effects of silver nanoparticles on denitrification and anammox in sediments of hypertrophic and mesotrophic lakes. Sci. Total Environ. 858, 159933 (2023).36343817
8. Abbas Q Transformation pathways and fate of engineered nanoparticles (ENPs) in distinct interactive environmental compartments: A review Environ. Int. 2020 138 105646 10.1016/j.envint.2020.105646 32179325
Abbas, Q. et al. Transformation pathways and fate of engineered nanoparticles (ENPs) in distinct interactive environmental compartments: A review. Environ. Int. 138, 105646 (2020).32179325
9. Zhao J Silver nanoparticles in aquatic sediments: Occurrence, chemical transformations, toxicity, and analytical methods J. Hazard. Mater. 2021 418 126368 10.1016/j.jhazmat.2021.126368 34329024
Zhao, J. et al. Silver nanoparticles in aquatic sediments: Occurrence, chemical transformations, toxicity, and analytical methods. J. Hazard. Mater. 418, 126368 (2021).34329024
10. Zhou Z Silver nanocubes monolayers as a SERS substrate for quantitative analysis Chin. Chem. Lett. 2021 32 1497 1501 10.1016/j.cclet.2020.10.021
Zhou, Z. et al. Silver nanocubes monolayers as a SERS substrate for quantitative analysis. Chin. Chem. Lett. 32, 1497–1501 (2021).
11. Hoai PTT Huong NTM Latest avenues on titanium oxide-based nanomaterials to mitigate the pollutants and antibacterial: Recent insights, challenges, and future perspectives Chemosphere 2023 324 138372 10.1016/j.chemosphere.2023.138372 36905998
Hoai, P. T. T. & Huong, N. T. M. Latest avenues on titanium oxide-based nanomaterials to mitigate the pollutants and antibacterial: Recent insights, challenges, and future perspectives. Chemosphere 324, 138372 (2023).36905998
12. Diem PNH Silver, gold, and silver-gold bimetallic nanoparticle-decorated dextran: Facile synthesis and versatile tunability on the antimicrobial activity J. Nanomater. 2020 2020 1 11 10.1155/2020/7195048
Diem, P. N. H. et al. Silver, gold, and silver-gold bimetallic nanoparticle-decorated dextran: Facile synthesis and versatile tunability on the antimicrobial activity. J. Nanomater. 2020, 1–11 (2020).
13. Anbumani D Green synthesis and antimicrobial efficacy of titanium dioxide nanoparticles using Luffa acutangula leaf extract J. King Saud Univ. Sci. 2022 34 101896 10.1016/j.jksus.2022.101896
Anbumani, D. et al. Green synthesis and antimicrobial efficacy of titanium dioxide nanoparticles using Luffa acutangula leaf extract. J. King Saud Univ. Sci. 34, 101896 (2022).
14. Tahir MY Sillanpaa M Almutairi TM Mohammed AAA Ali S Excellent photocatalytic and antibacterial activities of bio-activated carbon decorated magnesium oxide nanoparticles Chemosphere 2023 312 137327 10.1016/j.chemosphere.2022.137327 36410509
Tahir, M. Y., Sillanpaa, M., Almutairi, T. M., Mohammed, A. A. A. & Ali, S. Excellent photocatalytic and antibacterial activities of bio-activated carbon decorated magnesium oxide nanoparticles. Chemosphere 312, 137327 (2023).36410509
15. Shen H Liu Y One-step synthesis of hydrophobic magnesium hydroxide nanoparticles and their application in flame-retardant polypropylene composites Chin. J. Chem. Eng. 2018 26 10 2199 2205 10.1016/j.cjche.2018.08.008
Shen, H. & Liu, Y. One-step synthesis of hydrophobic magnesium hydroxide nanoparticles and their application in flame-retardant polypropylene composites. Chin. J. Chem. Eng. 26(10), 2199–2205 (2018).
16. Qu J Hybrid nanocomposite multinetwork hydrogel containing magnesium hydroxide nanoparticles with enhanced antibacterial activity for wound dressing applications Polymer 2022 251 124902 10.1016/j.polymer.2022.124902
Qu, J. et al. Hybrid nanocomposite multinetwork hydrogel containing magnesium hydroxide nanoparticles with enhanced antibacterial activity for wound dressing applications. Polymer 251, 124902 (2022).
17. Alves MM Enhanced antibacterial activity of rosehip extract-functionalized Mg(OH)2 nanoparticles: An in vitro and in vivo study Colloids Surf. B Biointerfaces 2022 217 112643 10.1016/j.colsurfb.2022.112643 35759895
Alves, M. M. et al. Enhanced antibacterial activity of rosehip extract-functionalized Mg(OH)2 nanoparticles: An in vitro and in vivo study. Colloids Surf. B Biointerfaces 217, 112643 (2022).35759895
18. Tran HN Lin CC Woo SH Chao HP Efficient removal of copper and lead by Mg/Al layered double hydroxides intercalated with organic acid anions: Adsorption kinetics, isotherms, and thermodynamics Appl. Clay Sci. 2018 154 17 27 10.1016/j.clay.2017.12.033
Tran, H. N., Lin, C. C., Woo, S. H. & Chao, H. P. Efficient removal of copper and lead by Mg/Al layered double hydroxides intercalated with organic acid anions: Adsorption kinetics, isotherms, and thermodynamics. Appl. Clay Sci. 154, 17–27 (2018).
19. Janani FZ Nanostructured layered double hydroxides based photocatalysts: Insight on synthesis methods, application in water decontamination/splitting and antibacterial activity Surf. Interfaces 2021 25 101263 10.1016/j.surfin.2021.101263
Janani, F. Z. et al. Nanostructured layered double hydroxides based photocatalysts: Insight on synthesis methods, application in water decontamination/splitting and antibacterial activity. Surf. Interfaces 25, 101263 (2021).
20. Chen R Study on the inhibition effect of nano-Mg(OH)2 to tea blackspot disease pathogenic fungi activity J. Agric. Biotechnol. 2019 27 1460 1466
Chen, R. et al. Study on the inhibition effect of nano-Mg(OH)2 to tea blackspot disease pathogenic fungi activity. J. Agric. Biotechnol. 27, 1460–1466 (2019).
21. Zhang Z A review of sulfate-reducing bacteria: Metabolism, influencing factors and application in wastewater treatment J. Clean. Prod. 2022 376 134109 10.1016/j.jclepro.2022.134109
Zhang, Z. et al. A review of sulfate-reducing bacteria: Metabolism, influencing factors and application in wastewater treatment. J. Clean. Prod. 376, 134109 (2022).
22. Baidukova O Skorb EV Ultrasound-assisted synthesis of magnesium hydroxide nanoparticles from magnesium Ultrason. Sonochem. 2016 31 423 428 10.1016/j.ultsonch.2016.01.034 26964968
Baidukova, O. & Skorb, E. V. Ultrasound-assisted synthesis of magnesium hydroxide nanoparticles from magnesium. Ultrason. Sonochem. 31, 423–428 (2016).26964968
23. Wu H Synthesis and size control of monodisperse magnesium hydroxide nanoparticles by microemulsion method J. Dispers. Sci. Technol. 2020 41 585 591 10.1080/01932691.2019.1594887
Wu, H. et al. Synthesis and size control of monodisperse magnesium hydroxide nanoparticles by microemulsion method. J. Dispers. Sci. Technol. 41, 585–591 (2020).
24. Kotresh MG Patil MK Sunilkumar A Sushilabai A Inamdar SR A study on the effect of reaction temperature on the synthesis of magnesium hydroxide nanoparticles: Comparative evaluation of microstructure parameters and optical properties Results Opt. 2023 10 100336 10.1016/j.rio.2022.100336
Kotresh, M. G., Patil, M. K., Sunilkumar, A., Sushilabai, A. & Inamdar, S. R. A study on the effect of reaction temperature on the synthesis of magnesium hydroxide nanoparticles: Comparative evaluation of microstructure parameters and optical properties. Results Opt. 10, 100336 (2023).
25. Stoeva MK Resistance and resilience of sulfidogenic communities in the face of the specific inhibitor perchlorate Front. Microbiol. 2019 10 654 10.3389/fmicb.2019.00654 31001230
Stoeva, M. K. et al. Resistance and resilience of sulfidogenic communities in the face of the specific inhibitor perchlorate. Front. Microbiol. 10, 654 (2019).31001230
26. Jabir T Influence of environmental factors on benthic nitrogen fixation and role of sulfur reducing diazotrophs in a eutrophic tropical estuary Mar. Pollut. Bull. 2021 165 112126 10.1016/j.marpolbul.2021.112126 33667934
Jabir, T. et al. Influence of environmental factors on benthic nitrogen fixation and role of sulfur reducing diazotrophs in a eutrophic tropical estuary. Mar. Pollut. Bull. 165, 112126 (2021).33667934
27. Niu ZS Human activities can drive sulfate-reducing bacteria community in Chinese intertidal sediments by affecting metal distribution Sci. Total Environ. 2021 786 147490 10.1016/j.scitotenv.2021.147490 33975107
Niu, Z. S. et al. Human activities can drive sulfate-reducing bacteria community in Chinese intertidal sediments by affecting metal distribution. Sci. Total Environ. 786, 147490 (2021).33975107
28. Geisler E Rahav E Bar-Zeev E Contribution of heterotrophic diazotrophs to N2 fixation in a eutrophic river: Free-living versus aggregate-associated Front. Microbiol. 2022 13 779820 10.3389/fmicb.2022.779820 35237246
Geisler, E., Rahav, E. & Bar-Zeev, E. Contribution of heterotrophic diazotrophs to N2 fixation in a eutrophic river: Free-living versus aggregate-associated. Front. Microbiol. 13, 779820 (2022).35237246
29. Liesirova T Nitrogen-fixing sulfate reducing bacteria in shallow coastal sediments under simulated resuspension Estuarine Coast. Shelf Sci. 2023 280 108165 10.1016/j.ecss.2022.108165
Liesirova, T. et al. Nitrogen-fixing sulfate reducing bacteria in shallow coastal sediments under simulated resuspension. Estuarine Coast. Shelf Sci. 280, 108165 (2023).
30. Zuo Z Free nitrous acid-based suppression of sulfide production in sewer sediments: In-situ effect mechanism Sci. Total Environ. 2020 715 136871 10.1016/j.scitotenv.2020.136871 32014769
Zuo, Z. et al. Free nitrous acid-based suppression of sulfide production in sewer sediments: In-situ effect mechanism. Sci. Total Environ. 715, 136871 (2020).32014769
31. Negm NA Altalhi AA Saleh Mohamed NE Kana MTHA Mohamed EA Growth inhibition of sulfate-reducing bacteria during gas and oil production using novel Schiff base diquaternary biocides: Synthesis, antimicrobial, and toxicological assessment ACS Omega 2022 7 40098 40108 10.1021/acsomega.2c04836 36385895
Negm, N. A., Altalhi, A. A., Saleh Mohamed, N. E., Kana, M. T. H. A. & Mohamed, E. A. Growth inhibition of sulfate-reducing bacteria during gas and oil production using novel Schiff base diquaternary biocides: Synthesis, antimicrobial, and toxicological assessment. ACS Omega 7, 40098–40108 (2022).36385895
32. Zhao YP High sulfide production induced by algae decomposition and its potential stimulation to phosphorus mobility in sediment Sci. Total Environ. 2019 650 163 172 10.1016/j.scitotenv.2018.09.010 30196216
Zhao, Y. P. et al. High sulfide production induced by algae decomposition and its potential stimulation to phosphorus mobility in sediment. Sci. Total Environ. 650, 163–172 (2019).30196216
33. Chen M Succession of sulfur bacteria during decomposition of cyanobacterial bloom biomass in the shallow Lake Nanhu: An ex situ mesocosm study Chemosphere 2020 256 127101 10.1016/j.chemosphere.2020.127101 32450355
Chen, M. et al. Succession of sulfur bacteria during decomposition of cyanobacterial bloom biomass in the shallow Lake Nanhu: An ex situ mesocosm study. Chemosphere 256, 127101 (2020).32450355
34. Chen M Black blooms-induced adaptive responses of sulfate reduction bacteria in a shallow freshwater lake Environ. Res. 2022 209 112732 10.1016/j.envres.2022.112732 35077715
Chen, M. et al. Black blooms-induced adaptive responses of sulfate reduction bacteria in a shallow freshwater lake. Environ. Res. 209, 112732 (2022).35077715
35. Novair SB Atigh ZBQ Lajayer BA Shu W Price GW The role of sulphate-reducing bacteria (SRB) in bioremediation of sulphate-rich wastewater: Focus on the source of electron donors Process Saf. Environ. Prot. 2024 184 190 207 10.1016/j.psep.2024.01.103
Novair, S. B., Atigh, Z. B. Q., Lajayer, B. A., Shu, W. & Price, G. W. The role of sulphate-reducing bacteria (SRB) in bioremediation of sulphate-rich wastewater: Focus on the source of electron donors. Process Saf. Environ. Prot. 184, 190–207. 10.1016/j.psep.2024.01.103 (2024).
36. Azeez F The effect of surface charge on photocatalytic degradation of methylene blue dye using chargeable titania nanoparticles Sci. Rep. 2018 8 7104 10.1038/s41598-018-25673-5 29740107
Azeez, F. et al. The effect of surface charge on photocatalytic degradation of methylene blue dye using chargeable titania nanoparticles. Sci. Rep. 8, 7104 (2018).29740107
37. Mohammadi FM Ghasemi N Influence of temperature and concentration on biosynthesis and characterization of zinc oxide nanoparticles using cherry extract J. Nanostruct. Chem. 2018 8 93 102 10.1007/s40097-018-0257-6
Mohammadi, F. M. & Ghasemi, N. Influence of temperature and concentration on biosynthesis and characterization of zinc oxide nanoparticles using cherry extract. J. Nanostruct. Chem. 8, 93–102 (2018).
38. Ezeuko AS Ojemaye MO Okoh OO Okoh AI Study on the toxicity of nanoparticles on antibiotic resistant bacteria in wastewater J. Water Process. Eng. 2021 41 102041 10.1016/j.jwpe.2021.102041
Ezeuko, A. S., Ojemaye, M. O., Okoh, O. O. & Okoh, A. I. Study on the toxicity of nanoparticles on antibiotic resistant bacteria in wastewater. J. Water Process. Eng. 41, 102041 (2021).
39. Chen R Study on the inhibition effect of nano-Mg(OH)2 to tea blackspot disease pathogenic fungi activity J. Agric. Biotechnol. 2019 27 8 1460 1466
Chen, R. et al. Study on the inhibition effect of nano-Mg(OH)2 to tea blackspot disease pathogenic fungi activity. J. Agric. Biotechnol. 27(8), 1460–1466 (2019).
40. Mahboob S Facile synthesis of gold and platinum doped titanium oxide nanoparticles for antibacterial and photocatalytic activity: A photodynamic approach Photodiagn. Photodyn. Ther. 2021 33 102148 10.1016/j.pdpdt.2020.102148
Mahboob, S. et al. Facile synthesis of gold and platinum doped titanium oxide nanoparticles for antibacterial and photocatalytic activity: A photodynamic approach. Photodiagn. Photodyn. Ther. 33, 102148 (2021).
41. Archana P Janarthanan B Bhuvana S Rajiv P Sharmila S Concert of zinc oxide nanoparticles synthesized using Cucumis melo by green synthesis and the antibacterial activity on pathogenic bacteria Inorg. Chem. Commun. 2022 137 109255 10.1016/j.inoche.2022.109255
Archana, P., Janarthanan, B., Bhuvana, S., Rajiv, P. & Sharmila, S. Concert of zinc oxide nanoparticles synthesized using Cucumis melo by green synthesis and the antibacterial activity on pathogenic bacteria. Inorg. Chem. Commun. 137, 109255 (2022).
42. Suresh S Antibacterial activity and photocatalytic oxidative performance of zinc oxide nanorods biosynthesized using Aerva lanata leaf extract Inorg. Chem. Commun. 2022 139 109398 10.1016/j.inoche.2022.109398
Suresh, S. et al. Antibacterial activity and photocatalytic oxidative performance of zinc oxide nanorods biosynthesized using Aerva lanata leaf extract. Inorg. Chem. Commun. 139, 109398 (2022).
43. Bai X Jarubula R Development of novel green synthesized zinc oxide nanoparticles with antibacterial activity and effect on diabetic wound healing process of excisional skin wounds in nursing care during sports training Inorg. Chem. Commun. 2023 150 110453 10.1016/j.inoche.2023.110453
Bai, X. & Jarubula, R. Development of novel green synthesized zinc oxide nanoparticles with antibacterial activity and effect on diabetic wound healing process of excisional skin wounds in nursing care during sports training. Inorg. Chem. Commun. 150, 110453 (2023).
44. Kavitha A R.P.A mini review on plant-mediated zinc oxide nanoparticles and their antibacterial potency Biocatal. Agric. Biotechnol. 2023 48 102654 10.1016/j.bcab.2023.102654
Kavitha, A. et al. R.P.A mini review on plant-mediated zinc oxide nanoparticles and their antibacterial potency. Biocatal. Agric. Biotechnol. 48, 102654 (2023).
45. Wang Z Toxic effects of zinc oxide nanoparticles as a food additive in goat mammary epithelial cells Food Res. Int. 2023 167 112682 10.1016/j.foodres.2023.112682 37087259
Wang, Z. et al. Toxic effects of zinc oxide nanoparticles as a food additive in goat mammary epithelial cells. Food Res. Int. 167, 112682 (2023).37087259
46. Ng CT Zinc oxide nanoparticles exhibit cytotoxicity and genotoxicity through oxidative stress responses in human lung fibroblasts and Drosophila melanogaster Int. J. Nanomedicine 2017 12 1621 1637 10.2147/IJN.S124403 28280330
Ng, C. T. et al. Zinc oxide nanoparticles exhibit cytotoxicity and genotoxicity through oxidative stress responses in human lung fibroblasts and Drosophila melanogaster. Int. J. Nanomedicine 12, 1621–1637 (2017).28280330
47. Eivazzadeh-Keihan R Alginate hydrogel-polyvinyl alcohol/silk fibroin/magnesium hydroxide nanorods: A novel scaffold with biological and antibacterial activity and improved mechanical properties Int. J. Biol. Macromol. 2020 162 1959 1971 10.1016/j.ijbiomac.2020.08.090 32814101
Eivazzadeh-Keihan, R. et al. Alginate hydrogel-polyvinyl alcohol/silk fibroin/magnesium hydroxide nanorods: A novel scaffold with biological and antibacterial activity and improved mechanical properties. Int. J. Biol. Macromol. 162, 1959–1971 (2020).32814101
48. Cui H Bai M Sun Y Abdel-Samie MAS Lin L Antibacterial activity and mechanism of Chuzhou chrysanthemum essential oil J. Funct. Foods 2018 48 159 166 10.1016/j.jff.2018.07.021
Cui, H., Bai, M., Sun, Y., Abdel-Samie, M. A. S. & Lin, L. Antibacterial activity and mechanism of Chuzhou chrysanthemum essential oil. J. Funct. Foods 48, 159–166 (2018).
49. Hu W Li C Dai J Cui H Lin L Antibacterial activity and mechanism of Litsea cubeba essential oil against methicillin-resistant Staphylococcus aureus (MRSA) Ind. Crops Prod. 2019 130 34 41 10.1016/j.indcrop.2018.12.078
Hu, W., Li, C., Dai, J., Cui, H. & Lin, L. Antibacterial activity and mechanism of Litsea cubeba essential oil against methicillin-resistant Staphylococcus aureus (MRSA). Ind. Crops Prod. 130, 34–41 (2019).
50. Mohammadkhani A Preparation and characterization of anticorrosive and antibacterial coatable nanocomposite based on zinc phosphate modified by hydroxy apatite/alginate: Investigation of electrochemical impedance spectroscopy (EIS) Case Stud. Chem. Environ. Eng. 2024 9 100694 10.1016/j.cscee.2024.100694
Mohammadkhani, A. et al. Preparation and characterization of anticorrosive and antibacterial coatable nanocomposite based on zinc phosphate modified by hydroxy apatite/alginate: Investigation of electrochemical impedance spectroscopy (EIS). Case Stud. Chem. Environ. Eng. 9, 100694 (2024).
51. Imade EE Ajiboye TO Fadiji AE Onwudiwe DC Babalola OO Green synthesis of zinc oxide nanoparticles using plantain peel extracts and the evaluation of their antibacterial activity Sci. Afr. 2022 16 e01152
Imade, E. E., Ajiboye, T. O., Fadiji, A. E., Onwudiwe, D. C. & Babalola, O. O. Green synthesis of zinc oxide nanoparticles using plantain peel extracts and the evaluation of their antibacterial activity. Sci. Afr. 16, e01152 (2022).
52. Mohapatra B Choudhary S Mohapatra S Sharma N Facile preparation and antibacterial activity of zinc oxide nanobullets Mater. Today Commun. 2023 34 105083 10.1016/j.mtcomm.2022.105083
Mohapatra, B., Choudhary, S., Mohapatra, S. & Sharma, N. Facile preparation and antibacterial activity of zinc oxide nanobullets. Mater. Today Commun. 34, 105083 (2023).
53. Aguilera G Carboxymethyl cellulose coated magnetic nanoparticles transport across a human lung microvascular endothelial cell model of the blood–brain barrier Nanoscale Adv. 2019 1 2 671 685 10.1039/C8NA00010G 36132237
Aguilera, G. et al. Carboxymethyl cellulose coated magnetic nanoparticles transport across a human lung microvascular endothelial cell model of the blood–brain barrier. Nanoscale Adv. 1(2), 671–685 (2019).36132237
54. Zhao S Effects of starvation stress on immunity and ATPase activity of Kuruma Prawn Marsupenaeus japonicus Fish. Sci. 2023 42 136 141
Zhao, S. et al. Effects of starvation stress on immunity and ATPase activity of Kuruma Prawn Marsupenaeus japonicus. Fish. Sci. 42, 136–141 (2023).
55. Postgate JR Recent advances in the study of the sulfate-reducing bacteria Bacteriol. Rev. 1965 29 425 441 10.1128/br.29.4.425-441.1965 5322044
Postgate, J. R. Recent advances in the study of the sulfate-reducing bacteria. Bacteriol. Rev. 29, 425–441 (1965).5322044
56. Postgate JR The sulphate reducing bacteria 1984 Cambridge University
Postgate, J. R. The sulphate reducing bacteria (Cambridge University, 1984).
57. Dong CX Investigation of Mg(OH)2 nanoparticles as an antibacterial agent J. Nanopart. Res. 2010 12 2101 2109 10.1007/s11051-009-9769-9
Dong, C. X. et al. Investigation of Mg(OH)2 nanoparticles as an antibacterial agent. J. Nanopart. Res. 12, 2101–2109 (2010).
58. Jiang YH Antibacterial activity and action target of phenyllactic acid against Staphylococcus aureus and its application in skim milk and cheese J. Dairy Sci. 2022 105 12 9463 9475 10.3168/jds.2022-22262 36270872
Jiang, Y. H. et al. Antibacterial activity and action target of phenyllactic acid against Staphylococcus aureus and its application in skim milk and cheese. J. Dairy Sci. 105(12), 9463–9475 (2022).36270872
59. Jiang YH Antibacterial mechanism of action of crude plantaricin LP21-2 against Escherichia coli and its potential application in yak milk LWT-Food Sci. Tech. 2024 202 116266 10.1016/j.lwt.2024.116266
Jiang, Y. H. et al. Antibacterial mechanism of action of crude plantaricin LP21-2 against Escherichia coli and its potential application in yak milk. LWT-Food Sci. Tech. 202, 116266 (2024).
