Denitrifying microbial community with the ability to bromate reduction in a rotating biofilm-electrode reactor

In this study, the microbial community for bromate reduction in a rotating biofilm-electrode reactor (RBER) was investigated. Continuous experiment demonstrated that the bromate reduction by an auto-hydrogenotrophic microbial community was inhibited by high concentration nitrate (50mg/L). The bacterial diversity of RBER were examined through the analyse of 16S rRNA gene sequences of clone libraries. The results showed that the bromate-reducing bacteria were phylogenetically diverse at the phylum level, representing the Firmicutes, Proteobacteria, Bacteroidetes and Actinobacteria. The relative abundances of these microbial community represented 99.1% of all phylum in the biofilms when bromate served as the sole electron acceptor. Meanwhile, the Bacillus strains became the largest phylotype and represented about 37% of the total bacteria in the biofilm, indicating that the genus Bacillus played the key role in the auto-hydrogenotrophic process. Moreover, three new bacterial genera, Exiguobacterium, Arthrobacter and Chlorobium appeared with the respective relative abundance being about 7.37%, 1.81%, and 0.52%, which might be the bromate-specific reducing bacteria.