Screening, Optimization and Production of Biosurfactants by Candida Species Isolated from Oil Polluted Soils

Biosurfactants are amphipathic molecules with both hydrophilic and hydrophobic moieties and are surface active agent that are produced extracellularly or as a part of cell membrane by bacteria, yeast and fungi. In the present study, six different microorganisms were isolated from oil contaminated soils. Screening of biosurfactant producing potential strain was done using oil spreading method, oil collapse method; emulsification method and MATH assay method. Using preliminary tests, the potential strain was identified as Pseudomonas aeruginosa, Candida tropicalis and Candida albicans. In oil spreading method, the organisms were produced maximum zone. High concentration of both the extracellular biosurfactant was produced by P. aeruginosa and intracellular biosurfactant was produced by C. tropicalis and C. albicans using emulsification method. In this present study, the MATH assay and statistical analysis revealed that C. tropicalis and C. albicans have higher hydrophobicity than P. aeruginosa. Optimization studies were carried out for biosurfactant production using C. tropicalis and C. albicans with different parameters like incubation period, temperature, pH and substrate concentration. The results showed the maximum production in the 6 day, 40°C and 6 respectively for both C. tropicalis and C. albicans, the substrate concentration was th 1.5% for C. tropicalis and 2.0% for C. albicans. The total quantity of production of biosurfactant was 1.71% for C. albicans and 0.91% biosurfactant was produced by C. tropicalis.