Mutagenesis and screening of highly efficient pyrene degrading strains by N+-implantation

In this study, nitrogen ion implantation was used to mutate a pyrene-degrading bacterium, Gordona sp. hbs1, which was isolated from a polycyclic aromatic hydrocarbons (PAHs) contaminated soil. The pyrene degradation characteristics of hbs1, including isotherm and pH effect were observed. 200 mg/L pyrene, 53.78% was degraded by hbs1, equals to 10.75 mg/L. The optimum initial pH for pyrene degradation was 7 to 7.5. The mutagenesis was conducted by 30 KeV nitrogen ion implantation with the doses of 5×10¹², 1×10¹³, 2×10¹³, 4×10¹³, 5×10¹³, 1×10¹⁴, 2×10¹⁴, 5×10¹⁴ ions/cm². The results showed that the optimum dose was 1×10¹⁴ ions/cm². Three highly pyrene degrading strains, hbs1-m11, hbs1-m23 and hbs1-m48 were obtained and their increased efficiencies were 18.72%, 10.71% and 13.10%, respectively. Furthermore, pyrene degrading rate of hbs1-m11 was higher than hbs1. These results imply that ion implantation could be a potential technology in environmental bioremediation.