Enhanced biosurfactant production through cloning of three genes and role of esterase in biosurfactant release

Kamaljeet Sekhon,Sunil Khanna,Swaranjit Cameotra

doi:10.1186/1475-2859-10-49

Abstract

BackgroundBiosurfactants have been reported to utilize a number of immiscible substrates and thereby facilitate the biodegradation of panoply of polyaromatic hydrocarbons. Olive oil is one such carbon source which has been explored by many researchers. However, studying the concomitant production of biosurfactant and esterase enzyme in the presence of olive oil in the Bacillus species and its recombinants is a relatively novel approach.ResultsBacillus species isolated from endosulfan sprayed cashew plantation soil was cultivated on a number of hydrophobic substrates. Olive oil was found to be the best inducer of biosurfactant activity. The protein associated with the release of the biosurfactant was found to be an esterase. There was a twofold increase in the biosurfactant and esterase activities after the successful cloning of the biosurfactant genes from Bacillus subtilis SK320 into E.coli. Multiple sequence alignment showed regions of similarity and conserved sequences between biosurfactant and esterase genes, further confirming the symbiotic correlation between the two. Biosurfactants produced by Bacillus subtilis SK320 and recombinant strains BioS a, BioS b, BioS c were found to be effective emulsifiers, reducing the surface tension of water from 72 dynes/cm to as low as 30.7 dynes/cm.ConclusionThe attributes of enhanced biosurfactant and esterase production by hyper-producing recombinant strains have many utilities from industrial viewpoint. This study for the first time has shown a possible association between biosurfactant production and esterase activity in any Bacillus species. Biosurfactant-esterase complex has been found to have powerful emulsification properties, which shows promising bioremediation, hydrocarbon biodegradation and pharmaceutical applications.

Highlights

Biosurfactants have been reported to utilize a number of immiscible substrates and thereby facilitate the biodegradation of panoply of polyaromatic hydrocarbons
Bacillus subtilis SK320 and the three recombinants were grown at 37°C, 120 rpm in the basal media Bushnell Hass Broth (BHB) in a 100 ml flask with 0.5% olive oil (v/v) (Olio di Oliva, Sasso, Milano, Italy) as a carbon source
Regulation of Biosurfactant production with various substrates Bacillus subtilis SK320 was grown on basal medium containing various substrates (0.5%, v/v) and monitored for growth and biosurfactant activity

Summary

Introduction

Biosurfactants have been reported to utilize a number of immiscible substrates and thereby facilitate the biodegradation of panoply of polyaromatic hydrocarbons. Studying the concomitant production of biosurfactant and esterase enzyme in the presence of olive oil in the Bacillus species and its recombinants is a relatively novel approach. Biosurfactants are surface active agents of microbial origin. They have the unique property of lowering the interfacial tension between two liquids. In literature the terms ‘biosurfactants’ and ‘bioemulsifiers’ are often used interchangeably owing to their unusual emulsifying property that makes them the molecules that enhance the accessibility and bioavailability of hydrophobic chemicals by forming stable emulsions and lowering the surface tension. The economics of producing biosurfactants has limited its commercial applications [1], but the production cost can be reduced by improving yield, rate, recovery and using cheap or waste substrates

Objectives

Methods

Results

Conclusion