Degradation of pyrene in soil and in vitro by a Bacillus lentus strain isolated from an asphalt plant soil site in Lagos, Nigeria

Abstract

A bacterium isolated from an asphalt plant soil and identified as a strain of Bacillus lentus was tested in vitro and in sterilized and native soils for ability to survive and sustain pyrene degradation over a period of 63 days. The exponential growth rate in vitro was 0.049 d^-1 and the doubling time 2.65 d. In the control flask without pyrene, organism density remained virtually constant. In sterilized soil seeded with Bacillus lentus LP32 pyrene concentration declined from 335.0 mg/kg to 8.56 mg/kg at the rate of 10.88 mg/kg/day and half-life of 5.67 days. Similarly, in the native soil seeded with organism there was a decline from 305.2 mg/kg to 8.58 mg/kg in 30 days at the rate of 9.89 mg/kg/day and half-life 5.82. The percentage pyrene degraded in both sterilized and native soils were similar, at 97.45% and 97.19% respectively. This study demonstrated the potential of Bacillus lentus LP32 to serve as seed for enhanced bioremediation of pyrene polluted soil.

Keywords: Bacillus, Biodegradation, Bioremediation, Gas chromatography, Pyrene