Aerobic degradation of diesel by a pure culture of Aspergillus terreus KP862582

Abstract

This study was conducted with a fungal strain isolated from a mining soil contaminated with total petroleum hydrocarbons (TPH) and properly identified by polymerase chain reaction (PCR) technique as Aspergillus terreus KP862582. The biodegradation potential of this pure culture was evaluated at laboratory scale; a wide diesel concentration range, from 10,000 to 50,000 mg diesel/kg soil (ppm), was tested using sterile soil microcosm over a 90-day period. Aerobic biodegradation of diesel by Aspergillus terreus KP862582 was significantly greater (p < 0:05) for 10,000, 20,000, and 30,000 ppm, with rate constant values of 0.025, 0.023, and 0.012 1/day, respectively. Cell viability at these concentrations was favored because it showed a significant increase during the first period of biodegradation (0-30 days), from this time onwards efficiency removal and cell viability decreased considerably. This pattern was observed as concentration of diesel increased, resulting in a much lower biodegradation rate for 40,000 ppm (0.005 1/day) and 50,000 ppm (0.002 1/day). Based on the results of this study it is concluded that the strain of Aspergillus terreus KP862582 can be used in the bioremediation of soils contaminated with petroleum hydrocarbons at concentrations of 10,000 and 20,000 ppm, and comply with the MPL established by the Mexican regulation.