Abstract

Sixteen colonies of lactic acid bacteria (LAB) were selected and screened for their ability to produce bacteriocin by agar well diffusion method using the supernatant of centrifuged test cultures.  Four isolates inhibited the growth of Listeria monocytogenesand Escherichia coli. Lactobacillus plantarum (6) and Lactobacillus brevis (5) were the most dominant species. The remaining were Lactobacillus lactis (2),Streptococcus lactis (2) and Lactobacillus fermentum (1). Lactobacillus spp. accounted for 87.5% of all isolates. LAB4 (Lactobacillus plantarum) showed some levels of antimicrobial activity after 15, 20 and 25 min heat treatments at 100^oC  againstListeria  monocytogenes . While antimicrobial activity of LAB70 (Lactobacillus lactis) was against both Listeria monocytogenes (after 20 and 25 min) and E. coli0157:H7 (after 15, 20 and 25 min) heat treatment at 100^oC. All the lactic acid bacteria used in this study produced cellulose. The correlation between cellulose production (an adhesion factor) and bacteria growth was highly significant after 72 h of incubation having a R² = 0.800. This study offers useful information on growth and cellulose production as factors affecting the efficacy of bacteriocin produced by these strains which could be good for biopreservation.

Key words: Lactic acid bacteria, antimicrobial, bacteriocin, cellulose, growth.