Anaerobic Degradation of Aromatic Compounds by Microorganisms in Paddy Field

Consortia demonstrated the high capacities of anaerobic degradation of various aromatic compounds, which were successfully enriched from gley paddy soils under different conditions. Phenol and cresol was decomposed anaerobically using nitrate, ferric oxide or sulfate as electron acceptors. Biphenyl was degraded to $CO_2$, especially without addition of external electron acceptor. Alkylphenols with middle length of alkyl chain, were co-metaboliocally degraded with the presence of hydroxylbenzoate as the co-substrate under nitrate reducing conditions. The microorganisms responsible for the anaerobic co-metabolism was Thauera sp. Reductive dechlorination activity was also observed for polychlorophenols, fthalide, polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins with the presence of lactate, formate or $H_2$ as electron donor. The fthalide dechlorinator was classified as Dehalobacter sp. Coupling of two physiologically-distinct anaerobic consortia, aromatic ring degrader and reductive dechlorinator, resulted in the mineralization of pentachlorophenol under anaerobic conditions. These results suggested that gley paddy soils harbored anaerobic microbial community with versatile capacity degrading aromatic compounds under anaerobic conditions.