Analysis of biodegradation by-products of nitrobenzene and aniline mixture by a cold-tolerant microbial consortium

•NB and AN degrading consortium isolated from the contaminated site was cold-tolerant.•Composition of the microbial consortium was analyzed by PCR-pyrosequencing method.•By-products of NB and AN mixture degradation by this consortium were first reported.•New by-products were generated by biodegrading of NB and AN simultaneously. A cold-tolerant microbial consortium, which can use nitrobenzene (NB) and aniline (AN) as sole carbon, nitrogen and energy sources, was isolated from an NB and AN contaminated site. Pilot 454 pyrosequencing analysis of the consortium showed that it was mainly made up of Pseudomonas spp. (98%). At 10°C, the consortium degraded the mixture of 50mg/L NB and 50mg/L AN at a similar rate as those achieved at 20°C and 30°C. The biodegradation by-products with different initial NB and AN concentrations at 10°C were analyzed. Azobenzene, azoxybenzene and acetanilide were observed in NB and AN mixtures degradation. These by-products are generated by the reaction between different intermediates resulting from the NB and AN degradation as well as the parent compounds. To the best of our knowledge, this is the first report confirming the by-products of NB and AN mixture biodegradation by a cold-tolerant microbial consortium.