Nikhitha D., Arpitha P. Thomas, Manoj Mathews, Nandini N.J. and Jisha Jacob
Abstract
The present study focused on isolating and identifying biosurfactant-producing bacterial strains from hydrocarbon-contaminated soils collected from five workshop sites in the Calicut district of Kerala, India Kuttikattoor, Irigadanpalli, Amabalakoth, Palazhi, and Velliparambu. Soil samples were enriched in mineral salt medium (MSM) using kerosene oil as the sole carbon source to selectively promote the growth of hydrocarbon-degrading bacteria. Following enrichment, distinct bacterial colonies were isolated, purified on nutrient agar, and preserved in nutrient broth for screening. The isolates were evaluated for biosurfactant production using oil spreading and emulsification index (E24) assays. Strains that tested positive in both assays were selected for molecular characterization. Genomic DNA was extracted from these isolates, and the 16S rRNA gene was amplified and sequenced to determine their taxonomic identity. Sequence analysis confirmed that the biosurfactant-producing strains belonged to the genus Bacillus, known for its metabolic versatility and surface-active compound production. These results indicate that contaminated soils in Calicut harbor native Bacillus species capable of producing biosurfactants, offering potential for use in environmental cleanup and industrial biotechnology applications.