Isolation and Characterization of Crude Oil Degrading Yeasts from the Geo-Marine Sites of the Arabian Gulf

Due to the frequent transportation and storage of oil and its products, oil spills and incidents are inevitable. The Arabian Gulf is one of the oil-rich regions of the world and is constantly threatened with oil pollution. In this study samples were taken from the water and sediment of the coastal areas of the north and northeast of the Arabian Gulf. The yeast strains were isolated using a selective enrichment culture and single-colony isolation technique. Characteristics such as cell surface hydrophobicity (MATH), emulsifier activity (E₂₄) and growth rate in different concentrations of crude oil were tested, and five strains with good activity were identified. The results of molecular identification confirmed that these strains belong to the following genus: Acrophialophora jodhpurensis strain C₃, Pichia kudriavzevii strain D₁, Hyphopichiakhmerensis strain U₁, and Candida tropicalis strain W₆. For each strain, the crude oil degrading ability was determined by spectrophotometric, gravimetric methods and FTIR methods. The results confirmed that the U₁, D₁ and C₃ strains can degrade crude oil in high concentrations (7%). The highest surface hydrophobicity was found in the W₆ strain (79.61). The emulsification activity is significant (42%) in the C₃ and D₁ strains. In summary, the yeast strains isolated in this research may be suitable alternatives for use in the bioremediation treatment of contaminated crude oil or some of its products in the Arabian Gulf.