Strain improvement of newly isolated <italic>Lactobacillus acidophilus</italic> MS1 for enhanced bacteriocin production.

Background: Lactic acid bacteria (LAB) are considered as GRAS (generally recognized as safe) and being used extensively as bio-preservatives. Bacteriocins, the metabolites of LAB, belong to a diverse family of naturally synthesized antimicrobial peptides. Objective: Strain improvement for enhanced bacteriocin production by physical and chemical mutagenesis. Methods: The bacterial strain was identified by 16S rDNA sequence analysis and improved by ultraviolet and ethidium bromide mutation. The resultant bacteriocin was biochemically characterized, purified and analyzed for mass determination. Results: Among mutants of identified <italic>Lactobacillus acidophilus</italic> MS1, the UV₆ (ultraviolet mutant) revealed 3400 AU bacteriocin activity with 42% survival rate and EB₅ (ethidium bromide mutant) exhibited 4020 AU with 28% survival rate. Bacteriocin of 6.5 kDa was purified by cation exchange and gel exclusion chromatography. It was found to be thermally stable at 100°C for 30 min and maintained the stability up to 121°C. The activity was monitored in a wide range of pH (4–9). Conclusion: Being resistant to several biochemical parameters, the bacteriocins have an effective incorporation in food, forage and pharmacy. There is a need to engage more efforts to explore novel bacteriocins and multifarious applications. [ABSTRACT FROM AUTHOR]