Insights into membrane disruption and oxidative stress in Gram-positive and Gram-negative bacteria: role of sodium benzoate and phenoxyethanol

This study investigates the antibacterial effects of two widely used preservatives in foods, pharmaceuticals, and personal care products, sodium benzoate and phenoxyethanol, on Gram-positive bacteria Staphylococcus aureus (ATCC 6538) and Gram-negative bacteria Pseudomonas aeruginosa (MTCC 1688). Despite their widespread usage, the exact antibacterial mechanisms of these preservatives are not yet fully understood. Our study demonstrated that the presence of SB and POE lead to extensive cellular rupture, membrane damage, and intracellular content leakage in bacteria. The results were validated through biochemical assays and visualized by transmission electron microscopy. The key findings from this study reveals that P. aeruginosa when treated with SB leads to cell shrinkage, whereas POE treatment leads to cellular bulging, under varied concentrations. Further analysis demonstrates that both compounds induce intracellular aldehyde accumulation leading to an increase in oxidative stress. This increase in oxidative stress can cause protein cross-linking, DNA and membrane destabilization, leading to cellular disruption. In summary, this study sheds light on the mechanisms behind the antibacterial effects and preservative's efficacy of these well-established compounds, offering valuable information for their ongoing use and potential enhancement in microbial control strategies.