Degradation of diesel-oil by a newly isolated Kocuria sediminis DDK6

A bacterial strain named DDK6 was isolated from diesel-contaminated soil from a petrol station in Al-Hofuf city, after enrichment on diesel oil. The strain DDK6 formed a reddish-pink colony with a 2 to 3 mm diameter after two days of incubation at 30°C. Cells were Gram-positive coccoid and formed no endospores. Phenotypic identification by the automated bacterial system, Vitek compact II, identified the DDK6 as Kocuria sp. at 95% probability level. The 16s rRNA gene sequencing analysis confirmed the identity of the strain as K. sedimins at an identity level of 99.15%. Results of Gas chromatography-mass spectrometry (GC-MS) revealed that the DDK6 degraded the C14-C19 compounds in diesel. In addition, the DDK6 strain consumed the majority (68%) of the carbon sources tested, including monosaccharides, disaccharides, polysaccharides, and sugar alcohols as noticed by biochemical characterization using the API 50CH. The cultural, biochemical, and molecular characteristics were in general agreement with the strain identification. The results confirmed the metabolic versatility of the strain DDK6, in addition to its ability to degrade diesel oil, thereby providing ecological and environmental merits for its application in bioremediation of hydrocarbon pollutants. Key words: Bioremediation, hydrocarbon, Kocuria, diesel oil.