Antagonistic activity of bacteriocin produced by Lactobacillus species from ogi, an indigenous fermented food

Seven Lactobacillus species each with one or more strains were isolated from various fermented cereal gruel's (ogi). They were identified as L. plantarum (3 strains), L. delbrueckii (1 strain), L. brevis (2 strains), L. reuteri (2 strains), L. casei (1 strain), L. fermentum (1 strain) and L. acidophilus (1 strain). Bacteriocin production was observed in cell-free supernatants of 8 of these strains with L. fermentum, L. delbrueckii and L. reuteri strains (white maize ogi) being negative. The bacteriocin produced by the eight strains inhibited the growth of various target organisms with the inhibition strongly noticed using Enterococcus faecalis as indicator. While catalase treatment, pH changes and heat treatment up to 80 °C had no effect on the activity of bacteriocin from these isolates, treatment with trypsin and proteinase K resulted in complete loss of inhibitory activity of the bacteriocins. A reduction in the inhibitory activity of the bacteriocins was also found to occur with increasing concentrations of glucose or peptone in the cultivation medium.