Antimicrobial effect of <i>lactobacillus</i> and <i>bacillus</i> derived biosurfactants on some food borne pathogens

Abstract

This study focused on the screening, production, extraction of biosurfactants from Lactobacillus and Bacillus bacteria and their antimicrobial properties against causal microorganisms of food borne infections (food borne pathogens). The biosurfactants were investigated for potential antimicrobial activity using disk diffusion. The food borne pathogens used included Salmonella typhi, Escherichia coli, Staphylococcus aureus, Salmonella paratyphi & Shigella dysenterae. Biosurfactant producing isolates were identified using blood haemolysis test, oil spreading technique and drop collapse assay. Emulsification assay of positive isolates was performed at pHs 4, 6, 8 and 10, and at temperatures 4ºC, 25ºC, 37ºC), with different concentrations of NaCl (4%, 6%, 8%, 10%), different sources of carbon (glucose, sucrose) and different nitrogen sources (urea, yeast). Biosurfactant L4 derived from Lactobacillus showed significant antagonistic property against Salmonella typhi at 25 μL concentration while B1 derived from Bacillus showed the most antagonistic activity against Shigella dysentrae at 40 μL concentration. The biosurfactants showed distinct antibacterial activity towards tested organisms.

Keywords: Biosurfactants, Lactobacillus, Bacillus, Antimicrobial Activity, biosurfactants