Phylogenetic analysis and characterization of an alkane-degrading yeast strain isolated from oil-polluted soil

The isolation and phylogenetic analysis of new yeast strains represent an important basis for the development of practical applications in biotechnology, industry, and bioremediation. The yeast strain RG1 was isolated from oil-polluted soil and characterized using morphological observations and the API 20C AUX system. The amplified ITS1-5.8S rDNA-ITS2 region had 653 bp and the restriction profiles obtained with Cfo I, Dde I, Hae III, Hinf I, and Hpa II endonucleases showed high similarities with those from Rhodotorula glutinis reference strains. The phylogenetic tree based on the Cfo I patterns confirmed the classification of the strain RG1 as belonging to the R. glutinis species. The studies performed during the present work indicate the existence of different mechanisms of n-alkane assimilation and biodegradation in the RG1 cells and their correlation with the production of biosurfactants. An evaluation of the emulsifying activity revealed that biosurfactant-mediated assimilation of n-alkanes decreases in the order n-decane > n-tetradecane > n-hexadecane. Biodegradation and emulsification assays using culture media supplemented with 1% n-alkanes as the sole carbon source showed that n-tetradecane represented the optimal hydrocarbon substrate for the growth of the strain RG1 over 14 days and for obtaining biosurfactants at stable rates.