Isolation, screening and molecular identification of biosurfactant producing bacteria from automobile workshops and optimization of parameters for biosurfactant production

Abstract

Biosurfactants are amphiphilic compounds produced usually within the cell surfaces of microbes or excreted extracellularly. It contains hydrophobic and hydrophilic parts that reduce surface tension and interfacial tension between individual molecules at the surface and interface respectively. The primary aim of the study was to isolate biosurfactant producing organisms from oil contaminated soil. Through primary and secondary screening methods, it was found that the five isolated organisms were capable of producing biosurfactants. Among these, the organism B, which showed the highest biosurfactant production was selected on the basis of emulsification index and oil displacement activity. The biochemical and molecular characterization of the organism B confirmed that the organism is Aeromonas caviae. The 16S rRNA was sequenced using Sanger dideoxy sequencing method inorder o characterize the biosurfuctant producing strain. The new Aeromonas caviae strain, KVMBS1 isolated from oil contaminated site was deposited in National center for Biotechnology Information (NCBI), Gene Bank, USA and accession number is MT322926.1. From the optimization of production parameters, its optimum temperature was found to be 37^oC and the optimum pH was found to be 7. The best carbon and nitrogen source was found to be kerosene and sodium nitrate respectively. The final production using the optimized parameters was done and the biosurfactant was extracted. The dry weight of the biosurfactant was found to be 0.051g. and it was concluded that the biosurfactant produced by Aeromonas caviae is a glycolipid. From the study, the isolated organism, Aeromonas caviae was found to be producing a glycolipid biosurfactant. It can be a promising candidate to be used in several industries.