Biosurfactant: A Potent Antimicrobial Agent

Abstract

Surfactant is an important class of chemicals with wide domestic and industrial application. Synthetic surfactant, however, used to increase the contaminant solubility are often toxic, representing an additional source of contamination. Microbially produced surface active compounds, i.e., biosurfactants are less toxic, biodegradable and have potential uses in large oil recovery operations, removal of oil spills, biodegradation of hydrocarbons from the soil, production of detergent, agro industries, manufacture of pharmaceutical products, etc. One of potential areas in which the usefulness of biosurfactants has been studied is its antimicrobial activity, which is catching good attention worldwide. The biosurfactants acts as an effective antimicrobial agent against a number of pathogenic organisms. In the present research work, a systematic isolation and screening program was under taken for obtaining biosurfactant producing bacteria. After sampling in mineral salt medium, a total of 31 isolates were screened from the samples collected from Uran sea coast, Mumbai and local Garage and Petrol pump. After primary and secondary screening procedures like hemolysis, emulsification index, oil spread technique and surface tension measurement, 2 isolates, namely 21Y and 14X were selected. The emulsification index for the 2 isolates was 100% in petrol and diesel in 24 hrs. The isolates reduced surface tension of the MS medium as follows: 21Y: 52.5 Dynes/cm to 39.1 Dynes/cm and 14X: 51.9 Dynes/cm to 41.2 Dynes/cm in a period of 96 hrs. The MS medium was optimized by Plackett- Burman design for the 2 isolates. The biosurfactants was purified by acid precipitation method. The antimicrobial activity tested for the purified surfactant was effective against E. coli (NCIM 2065), B. subtilis (NCIM 2063), and S. aureus (NCIM 5021).