Rhodococcus olei sp. nov., with the ability to degrade petroleum oil, isolated from oil-contaminated soil.

A Gram-stain-positive, non-motile, creamy-white and rod-coccus shaped actinobacterium, designated strain Ktm-20, capable of degrading petroleum oil was isolated from oil-contaminated soil. Strain Ktm-20 was able to grow at 15-37 °C, at pH 5.5-10.0 and at 0.0-2.0 % (w/v) NaCl concentration. This strain was taxonomically characterized by a polyphasic approach. The 16S rRNA gene sequence analysis showed that strain Ktm-20 belonged to the genus Rhodococcus and is closely related to Rhodococcus triatomae DSM 44892, Rhodococcus pedocola UC12, Rhodococcus wratislaviensis NBRC 100605, Rhodococcus agglutinans CFH S0262 and Rhodococcus canchipurensis MBRL 353T (98.8, 98.7, 98.5, 98.4 and 98.3 % gene sequence similarity, respectively). The only respiratory quinone was MK-8(H2); the major polar lipids were phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylinositol and phosphatidylinositol mannoside; and the predominant fatty acids were C16 : 0, summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c) and C18 : 1ω9c. The cell-wall peptidoglycan contained meso-diaminopimelic acid; and galactose, glucose, arabinose and ribose were detected as diagnostic sugars from whole-cell hydrolysates. Mycolic acids were detected. The DNA G+C content was 70.9 mol%. The DNA-DNA relatedness values between strain Ktm-20 and closely related species of the genus Rhodococcus were between 38.3-25.3 %, which falls below the threshold value of 70 % for the strain to be considered as novel. The morphological, physiological, chemotaxonomic and phylogenetic analyses clearly distinguished this strain from its closest phylogenetic neighbours. Thus, strain Ktm-20 represents a novel species of the genus Rhodococcus, for which the name Rhodococcus olei sp. nov. is proposed. The type strain is Ktm-20 (=KEMB 9005-695=KACC 19390=JCM 32206).