Characteristics of gamma-hexachlorocyclohexane biodegradation by a nitrogen-fixing cyanobacterium, Anabaena azotica

摘要

Biodegradation of gamma-hexachlorocyclohexane (lindane) by a nitrogen-fixing cyanobacterium isolated from Chinese paddy soils, Anabaena azotica 118, was investigated. Lindane with an initial concentration of 0.2 mg L-1 in the cultures had no negative effect on the chlorophyll a concentration of A. azotica after 5 d exposure. The tolerance of this cyanobacterium to lindane indicates that it has the potential to biodegrade lindane. The degradation experiments show that the percentage of lindane removal efficiency by A. azotica was 48.8% after 5 d, at an initial lindane concentration of 0.2 mg L-1 and initial A. azotica chlorophyll a concentration of 50 mg L-1. The calculated half-life was 4.78 d. Elevated culture temperature, irradiation, and usage of nitrate as the nitrogen source in the cultures could increase the biodegradation efficiency of lindane. gamma-Pentachlorocyclohexene was detected as a metabolite of lindane. The ability of A. azotica to biodegrade lindane has potential use in the bioremediation for this organochlorine pesticide.