Bacteriocin production by lactic acid bacteria and their antioxidant property

Lactic acid bacteria (LAB) are well known for their health benefits and hence they have wide application in food industries. These lactic acid bacteria produce bacteriocin, low molecular weight protein, which inhibit the growth of several closely related bacteria. In present study, out of 25 lactic acid bacteria 9 isolates produce higher lactic acid were evaluated for their ability to produce bacteriocin. Their growth pattern suggested that L10 showed highest growth compared to other. These LAB were examined for their antimicrobial activity against pathogens and their results revealed that all the isolates inhibit the growth of Staphyoloccus, Enterococcus, Serratia, Micrococcus, however, unable to inhibit growth of E. coli, Salmonella, Proteus, and Yersinia. Isolates L1 to L4 shows inhibition of Listeria monocytogens while rest of bacteria were unable to show antimicrobial activity against it. Antioxidant activity measured using FRAP assay suggested that isolated L6 (0.236 mM/g) showed highest antioxidant followed L3 and L11 which showed similar antioxidant activity (0.207 mM/g). Bacteriocin was partially purified using ammonium precipitation. Quantification of partially purified bacteriocin revealed that highest production was by isolate L3 (32.2 IU) followed by L6 (30.45 IU) and L1 (30.38 IU). Among all the isolates L3 showed higher antioxidant and higher bacteriocin production and hence it was identified as Enterococcus faecium. Thus, potential culture can be used for inhibition of pathogenic microbes by its antimicrobial bacteriocin production.