Isolation and characterization of biosurfactant producing bacteria having antimicrobial activity isolated from oil contaminated sites

Biosurfactants are surface active amphiphilic compounds that reduce the surface tension of liquids, thereby increase the miscibility of hydrophobic compounds. One of the isolate from oil contaminated site was tested for its ability to produce biosurfactants. The bacterium was identified on the basis of morphological and biochemical characterization and found to be Pseudomonas putida SOL-10. The isolate was tested for biosurfactant production under shake flask fermentation and found to be potent biosurfactant producer. The biosurfactant production was analyzed by surface tension and emulsification index (E24%) measurements. In this study the biosurfactant was produced by a newly isolated Pseudomonas putida SOL-10at optimized conditions. The biosurfactant produced by the isolate reduced the surface tension of culture broth from 43.6–29.9m.N.m^-1 achieving a maximum biosurfactant concentration of 4.5g/L after 72 hours of incubation. The biosurfactant also demonstrated a good antimicrobial activity as well as the capability to enhance the antimicrobial effect of some antibiotics. The current study describes the effect of biosurfactant with Ampicillin, Ciprofloxacin and Cefixime, against Escherichia coli, Bacillus subtilis, and Klebsiella pneumonia. The results demonstrated promising antimicrobial activity enhancing effect of the biosurfactant and suggested a possibility of the biosurfactant to be used with antibiotic formulations in order to increase the effectiveness of antimicrobials against multidrug-resistant pathogenic bacteria.

Keywords: Pseudomonas putida, biosurfactant, characterization, antimicrobial activity, antibiotics, surface tension