Oxidation of aliphatic, branched chain, and aromatic hydrocarbons by Nocardia cyriacigeorgica isolated from oil-polluted sand samples collected in the Saudi Arabian Desert

A soil bacterium isolated from oil-polluted sand samples collected in the Saudi Arabian Desert has been determined as Nocardia cyriacigeorgica, which has a high capacity of degrading and utilizing a broad range of hydrocarbons. The metabolic pathways of three classes of hydrocarbons were elucidated by identifying metabolites in cell-free extracts analyzed by GC/MS and HPLC/UV-Vis in comparison with standard compounds. During tetradecane oxidation, tetra-decanol; tetradecanoic acid; dodecanoic acid; decanoic acid could be found as metabolites, indicating a monoterminal degradation pathway of n-alkanes. The oxidation of pristane resulted in the presence of pristanoic acid; 2-methylglutaric acid; 4,8-dimethylnonanoic acid; and 2,6-dimethylheptanoic acid, which give rise to a possible mono- and di-terminal oxidation. In case of sec-octylbenzene, eight metabolites were detected including 5-phenylhexanoic acid; 3-phenylbutyric acid; 2-phenylpropionic acid; beta-methylcinnamic acid; acetophenone; beta-hydroxy acetophenone; 2,3-dihydroxy benzoic acid and succinic acid. From these intermediates a new degradation pathway for sec-octylbenzene was investigated. Our results indicate that N. cyriacigeorgica has the ability to degrade aliphatic and branched chain alkanes as well as alkylbenzene effectively and, therefore, N. cyriacigeorgica is probably a suitable bacterium for biodegradation of oil or petroleum products in contaminated soils.