Crude oil and polycyclic aromatic hydrocarbons (PAHs) biodegradation by Exophiala sp. UTMC 5043

Today, crude oil products are one of the most widely used chemicals in the world. Daily, large volumes of crude oil and their derivatives are poured into the environment. The aim of this study was to isolate and evaluate Iranian indigenous yeast strains for the purpose of bioremediation of crude oil pollutants. Soil samples were collected from different oil-contaminated areas of Iran. The samples were cultured for 14 days on Bushnell Hass medium containing 0.5 % crude oil and 100 mg l-1 tetracycline. The crude oil degradation was measured by TPH assay at 420 nm. Removal of 100 ppm of phenanthrene, anthracene, and pyrene as model polycyclic aromatic hydrocarbons (PAHs) was studied using HPLC method. The superior yeast strain was identified by ITS gene sequencing and alignment in the NCBI database. Totally, 47 yeast strains were isolated. TPH assay showed that FA14 isolate with 89% degradation rate within 14 days was the most powerful isolate in the removal of PAHs. ITS gene sequencing followed by alignment in NCBI indicated that FA14 belongs to the genus Exophiala sp., showing 99% similarity. Furthermore, the results indicated that within 14 days phenanthrene, anthracene, and pyrene were degraded by FA14 with the rate of 97.67 %, 57.0 %, and 95.38 %, respectively. Our results showed that Exophiala sp. has a high ability for biodegradation of crude oil and PAHs. Therefore, it could be introduced as a potent strain for bioremediation of oil-contaminated soil samples