Biodegradation of aniline by a novel bacterial mixed culture AC

- We develop a mixed culture, which can degrade aniline effectively.
- The culture can tolerate and degrade aniline at high concentrations.
- The microbial populations in the culture were determined.
- The immobilized system exhibits good degradation ability in different environment.
- Two intermediates of aniline were identified.

In this study, a novel bacterial mixed culture AC, capable of degrading aniline, was developed by us. The mixed culture presented better aniline degradation abilities comparing with different pure strains. Aniline at high concentrations could be tolerated and degraded by the mixed culture. An almost complete degradation of aniline at the concentration of 1500 mg L−1 was observed within 60 h. To provide further insight into the microbial diversity of the bacterial mixed culture, polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) and high-throughput sequencing analyses were performed. PCR-DGGE profiles revealed that the microbial community had changed with varying initial concentrations of aniline. The taxonomic classification of the bacterial communities showed that the acclimated mixed culture was mainly composed of Serratia, Escherichia/Shigella, Bacillus and Acinetobacter. The mixed culture was immobilized by entrapment in different polumeric matrices. The immobilized bead exhibited good activity for aniline degradation and kept stable during successive repeated experiments. The effects of physico-chemical parameters on the aniline degradation were determined. Comparing with the free cells, the immobilized bead exhibited better degradation ability in wide range of pH, temperature and salinity. HPLC analysis showed that the mixed culture could convert aniline to catechol, and then catechol was further biodegraded to cis, cis-muconic acid. Ames test showed that the metabolic transformation products of aniline had no inherent toxicity. All these results showed that the mixed culture had a great potential to be used in the treatment of wastewater containing aniline.