The Isolation and Characterizations of a Alkanes-Degrading Bacterium Rhodococcus sp 15-3.

A bacterial strain 15-3 degrading aromatic and aliphatic hydrocarbons of oil was isolated from crude oil-polluted soils and identi-fied as Rhodococcus sp. based on the 16S rDNA sequences and morphological, biochemical and physiological characteristics. Strain 15- 3 could use n-octadecane as sole carbon resource and degrade 96.9% n- octadecane(500 mg·L-1)after 48 h of incubation. The optimal temperature, pH and NaCl concentration for degrading n-octadecane by strain 15- 3 were 30 ℃, pH7.0 and 2%NaCl respectively. It still had high ability to degrade n-octadecane even at low-temperature(10 ℃) and high- salinity(4%～5% NaCl). Strain 15- 3 could degrade C13￣C32n- alka- nes, pristine and aromatic hydrocarbon in the crude oil. In the media containing 5 g·L-1crude oil strain 15- 3 degraded 60.33% crude oil, more than 90% C13 ￣C31n- alkanes and 63.61% aromatic hydrocarbons at 30 ℃ and 5 d incubation. The biosurfactants were produced by strain 15- 3 in the degradation of paraffin with the decrease of surface tension from 58.11 mN·m-1 to 36.6 mN·m-1, which implying that strain 15- 3 had the abilities for emulsification and dispersancy to crude oil.