Isolation and characterization of a nitrosoguanidine-induced Enterococcus faecium MTCC 5153 mutant defective in enterocin biosynthesis

Enterocin A (EntA) is a low molecular weight, heat-stable, chromosomally encoded class IIa bacteriocin produced by several strains of Enterococcus faecium. In this study, a mutated strain of E. faecium MTCC 5153 was characterized for its sensitivity to EntA, immunity function and for the production of induction factor. Nucleotide sequencing of the putative promoter of the entA operon suggested point mutations upstream of the entA gene. The mutant was sensitive to several class IIa bacteriocins and was found to adsorb 20% more bacteriocin compared to its wild-type counterpart.