Isolation and characterization of biosurfactant producing bacteria from groundnut oil cake dumping site for the control of foodborne pathogens

Abstract

Infection and intoxication are two common types of foodborne illnesses throughout the world. The aim of the present work was to isolate and characterize biosurfactant producing bacteria from groundnut oil cake dumping sites and evaluate their biocontrol effects against foodborne pathogens. Bacteria were isolated by enrichment culture technique and preliminary screening method. Biosurfactant activity evaluation was carried out by oil displacement, drop collapse test, lipase activity, hemolytic activity, emulsification index and emulsification assay methods. 16s rRNA sequence analysis was used for the isolate identification. Crude biosurfactant was extracted by acid precipitation method and characterized using FTIR (Fourier Transform Infrared Spectroscopy). Antibacterial activity was investigated using disc diffusion method. CMC and surface reduction were analyzed by DuNouy tensiometer. Top 10 strains were selected for biosurfactant activity assessment from the total 30 isolates. In addition, 16s rRNA sequence identified that the potential isolate was Bacillus pseudomycoides OR 1. Then, FTIR result of the extracted biosurfactant established the extract as a lipopeptide based on the absorption peaks at 3500 to 3200 cm−1 and 2963 to 2854.68 cm−1, respectively. 50 μg/mL of lipopeptide showed the highest antibacterial activity. Critical Micelle Concentration (CMC) of the lipopeptide was 60 mg/L and it reduced the surface tension of water from 71.6 to 31.6 mN/m. Hence, this study widens the scope to employ the bacterial lipopeptide surfactant as a promising biocontrol agent against foodborne pathogens.