Degradation of aliphatic and aromatic hydrocarbon mixture by a <i>Rhodococcus</i> sp.

<i>Rhodococcus</i> sp. strain p52, an aerobic dioxin degrader, was capable of utilizing petroleum hydrocarbons as the sole sources of carbon and energy for growth. In the present study, the degradation of the mixture of aliphatic hydrocarbons (hexadecane and tetradecane) and aromatic hydrocarbons (phenanthrene and anthracene) by strain p52 was examined. The results showed that the degradation of phenanthrene was enhanced in the presence of hexadecane or tetradecane due to increased bioavailability and improved cell surface hydrophobicity, which facilitated better substrate uptake. Conversely, the degradation of hexadecane and tetradecane decreased in the presence of aromatic hydrocarbons, likely due to the cometabolic effect, metabolic regulation, substrate competition, and the shift in enzyme activity. Moreover, the removal of 4.4 g L^-1 diesel fuel, a complex mixture of aliphatic hydrocarbons and aromatic hydrocarbons, was investigated and 63.7% of oil contents were depleted within 96 h. Therefore, strain p52 showed the potential to remove petroleum pollutants.