Molecular diversity of bacterial community of dye wastewater in an anaerobic sequencing batch reactor

Abstract

Anaerobic sequencing batch reactor has proven more effective than aerobic systems in treating dye-containing wastewaters which usually contain refractory dyes and organic chemicals. In this study, the composition and diversity of bacterial community present in an anaerobic sequencing batch reactor used for treating dye wastewater were determined by both high-through pyrosequencing and screening environmentally derived gene library based on 16S rRNA gene sequences. Our results demonstrated that Bacteroidetes represented the dominant phylum in dye wastewater, while the second and third most abundant phyla were Firmicutes and Proteobacteria. The genus Enterococcus from phylum Firmicutes was the dominant genus in the bacterial community of wastewater, followed by the genus Novispirillum, which was classified into phylum Alphaproteobacteria. The majority of sequences from environmental Alphaproteobacteria specific 16S rRNA gene library were assigned into genus Novispirillum and Rhodobacter, which were in agreement with our pyrosequencing results. The aforementioned two genera represented dominant Alphaproteobacteria community, which may perform important roles in degrading refractory dyes and organic chemicals in the anaerobic sequencing batch reactor. The results demonstrated that a wide variety of bacterial species were identified at the genera level and some potential degraders such asEnterococcus, Lactobacillus, Novispirillum and Rhodobacter were abundant in the reactor, which potentially contributed to the strong dye reduction ability. Key words: Dye wastewater, anaerobic sequencing batch reactor, 16S rRNA gene, pyrosequencing, bacterial diversity.