Purification and identification of a surfactin biosurfactant and engine oil degradation by Bacillus velezensis KLP2016

Engine oil used in automobiles is a threat to soil and water due to the recalcitrant properties of its hydrocarbons. It pollutes surrounding environment which affects both flora and fauna. Microbes can degrade hydrocarbons containing engine oil and utilize it as a substrate for their growth. Our results demonstrated that cell-free broth of Bacillus velezensis KLP2016 (Gram + ve, endospore forming; Accession number KY214239) recorded an emulsification index (E₂₄%) from 52.3% to 65.7% against different organic solvents, such as benzene, pentane, cyclohexane, xylene, n-hexane, toluene and engine oil. The surface tension of the cell-free broth of B. velezensis grown in Luria-Bertani broth at 35 °C decreased from 55 to 40 mN m^-1at critical micelle concentration 17.2 µg/mL. The active biosurfactant molecule of cell-free broth of Bacillus velezensis KLP2016 was purified by Dietheylaminoethyl-cellulose and size exclusion chromatography, followed by HPLC (RT = 1.130), UV-vis spectrophotometry (210 nm) and thin layer chromatography (R_f = 0.90). The molecular weight of purified biosurfactant was found to be ~ 1.0 kDa, based on Electron Spray Ionization-MS. A concentration of 1980 × 10^-2 parts per million of CO₂ was trapped in a KOH solution after 15 days of incubation in Luria-Bertani broth containing 1% engine oil. Our results suggest that bacterium Bacillus velezensis KLP2016 may promise a new dimension to solving the engine oil pollution problem in near future.