Heavy Metal Stress Tolerance by Serratia nematodiphila sp. MB307: Insights from Mass Spectrometry-based Proteomics

Background: Heavy metals impact living organisms deleteriously when they exceed the required limits. Their remediation by bacteria is a much-pursued area of environmental research. In this study, we explored the quantitative changes of four heavy metals (cadmium, chromium, zinc, copper), on the global and membrane proteome of gram-negative S. nematodiphila MB307. This is a versatile bacterium, isolated from the rhizosphere of heavy metal tolerating plant and equipped with characteristics ranging from useful biopeptide production to remediation of metals. Methods: We explored changes in the static end products of coding DNA sequences, i.e., proteins after 24 incubation under metal stress, using LC-MS/MS. Data analysis was done using MaxQuant software coupled with the Perseus package. Results: Up and downregulated protein fractions consisted prominently of chaperones, membrane integrity proteins, mobility or transporter proteins. Comparative analysis with previously studied bacteria and the functional contribution of these proteins to metal stress offer evidence for the survival of S. nematodiphila under high concentrations of selected metals. Conclusion: The outcomes validate that this soil-derived bacterium is well attuned to removing these metals from the soil and water, and may be additionally useful for boosting the phytoremediation of metals. This study delivers interesting insights and overlays ground for further investigations on the mechanistic activity of this bacterium under pollutant stress.