Induction of Bacteriocin Production by Lacticaseibacillus rhamnosus Using the Co-culture Method

Background: - The rise of antibiotic-resistant bacterial strains in the past decade has led to research on the microorganisms in the human gut and their interactions with pathogenic counterparts. The human gut microbiome houses bacteria like Lactobacilli , which produces bioactive metabolites, called bacteriocins which are known for their antimicrobial activity against disease-causing microorganisms. However, their production is limited in monocultures which can be improved by introducing bacteriocinogenic pathogenic strains in the culture. To enhance bacteriocin production, we have co-cultured Lacticaseibacillus rhamnosus with Staphylococcus aureus , a pathogenic inducer strain in different media like MRS, proso millet modified media (PmMRS) [1], and foxtail millet modified media (FmMRS) [2]. Results: - Antimicrobial assays conducted on bacteriocin extracts revealed potent inhibitory effects against prevalent food-borne pathogenslike Staphylococcus aureus (MTCC[3] 1430), Shigella flexneri (MTCC1457) and Enterobacter cloacae (MTCC 509). The SEM analysis of the co-cultures corresponded to the results from the antimicrobial assay. The bacteriocin extract was analyzed using SDS-PAGE and MALDI-TOF analysis and it exhibited 58% sequence similarity with a translocase protein in Zymomonas mobilis subsp. Mobilis (ATCC31821) and 20% sequence similarity with a bioactive protein produced by Lactiplantibacillus plantarum WCFS5 . Encapsulation of the extract in chitosan-based nanoparticles was pursued to enhance its antimicrobial effectiveness. Conclusion: - While potential applications against foodborne pathogens and antibiotic-resistant bacteria are promising, further research, including purification and delivery optimization, is imperative for practical implementation. This work sheds light on harnessing microbial interactions and bioactive compounds for addressing antibiotic resistance challenges.