Biosurfactants are amphipathic compounds with surface activity and emulsification ability. In addition, these compounds are reported to induce the production of plant growth promoting substances, hence, plays a vital role in plant growth and development. A plethora of microorganisms capable of producing biosurfactant compounds which helps to improve the soil quality and nutrient uptake by plants have been reported. Developing microbial inoculants producing biosurfactants to cleanse contaminated agricultural soils assumes greater significance in the wake of heavy metal and oil pollution due to anthropogenic activities. Therefore, the present study was carried out to isolate and screen potential biosurfactant-producing bacteria from contaminated soils and phyllosphere of different plants grown in oil and heavy metal contaminated soils. In the present study a total of 95 bacterial isolates were isolated by leaf imprint method and soil enrichment culture technique from phyllosphere and soil, respectively. Further, potential isolates were screened for biosurfactant production through qualitative assay such as oil spreading test, drop collapse test and penetration assay. Among the 95 bacterial isolates, 63 isolates were able to produce biosurfactants. These promising isolates were subjected to quantitative assay like emulsification index, bacterial adhesion to hydro carbons (BATH) assay and surface tension. The isolate BPB-47 isolated from phyllosphere (Ficus ingens) of Raichur petroleum contaminated area showed highest reduction in surface tension (27.15 mN/m), whereas the highest emulsification index were recorded by BSB-24 (72 ) and BPB-4 (72 ) isolated from petroleum contaminated soil of Raichur and phyllosphere (Psidium guajava) of Peenya heavy metal contaminated area, respectively. The isolate BSB-22 (78.67) which was isolated from fly ash contaminated soil of Shaktinagar, Raichur district of Karnataka showed highest bacterial adhesion to hydrocarbons compared to all other isolates.
展开▼
