Anaerobic degradation of 2-chloro-4-nitroaniline by Geobacter sp. KT7 and Thauera aromatica KT9

Abstract

2-chloro-4-nitroaniline is a nitroaromatic compound widely used in industrial and agricultural sectors, causing serious environmental problems. This compound and some of its analogs were utilized by two Fe3+-reducing microbial strains Geobacter sp. KT7 and Thauera aromatica KT9 isolated from contaminated sediment as sole carbon and nitrogen sources under anaerobic conditions. The anaerobic degradation of 2-chloro-4-nitroaniline by the mixed species was increased approximately by 45% compared to that of individual strains. The two isolates' crossfeeding, nutrient sharing and cooperation in the mixed culture accounted for the increase in degradation rates. The determination of degradation pathways showed that Geobacter sp. KT7 transformed the nitro group in 2-chloro-4-nitroaniline to the amino group following by the dechlorination process, while T. aromatica KT9 dechlorinated the compound before removing the nitro group and further transformed it to aniline. This study provided an intricate network of 2-chloro-4-nitroaniline degradation in the bacterial mixture and revealed two parallel routes for the substrate catabolism.