Production and characterization of biosurfactant by indigenous halotolerant Microbacterium sp. , isolated from Qom saline soils lake

Biosurfactants are biological surface active compounds produced by fungi, yeast and bacteria. These amphiphilic compounds can reduce surface tension and interfacial tension between individual molecules. The aims of this investigation was screening of biosurfactant producing halotolerant Actinobacteria species from the unexplored regions of Qom saline lake.

About 110 soil actinobacteria isolated strains were initially screened and then teste for their ability to BS production. Conventional screening methods of BS carried out using blood hemolysis, drop collapse method,oil spreading and surface tension measurements. 16S rRNA sequencing was done for the best biosurfactant producer strain. Further the partially purified BS was characterized by TLC, FTIR and compositional analysis. BS production was optimized using different carbon & nitrogen sources and optimized by different culture conditions such as temperatures, pH and stirring rate.

15 out of 110 isolates were able to tolerate high salt concentrations up to 10% . 8 isolated strains were BS producer. Isolate No.9 showed 99% similarity to Microbacterium paraoxidans by 16S rRNA gene sequencing method. Compositional analysis methods proved a glycolipid structure of BS. Sucrose and yeast extract were identified as the most appropriate carbon and nitrogen source, respectively. Maximum production of BS was obtained in pH 7,at temperature 27 oC and stirring rate 170 rpm.

These findings emphasize that such bacterial strains with superior BS production may find their potential application in bioremediation marine and soil ecosystem.