Analysis of metagenome in a full scale tannery wastewater treatment

Bioaugmentation of tannery wastewater was effective in industrial scale using the novel consortium BM-S-1. The aim of this study was to explore the structure of the microbial communities and the functional genes involved in the nitrogen removal. We used Illumina MiSeq Sequencer to conduct metagenome sequencing of microbial communities in the different stages of the treatment including buffering (B), primary aeration (PA), secondary aeration (SA) and sludge digestion (SD). The analysis of metagenome bioinformatic analysis demonstrated that four phyla Proteobacteria, Bacteriodetes, Firmicutes and Actinobacteria were dominant in the treatment process. The dominant genera were Burkholderia, Polaromonas, Albidiferax, Acidovorax, Geobacter, Dechloromonas, Pseudomonas, Rhodopseudomonas and others. Genes associated Nitrogen (N) metabolism were identified. Ssuch genesas gGlutamate synthase (GS), glutamate dehydrogenase (GDH), nitric oxide reductase (NIOR), nNitrous oxide reductase (NOOR), nitrate reductase (NAR), NAD.P.H nitrite reductase (NNIR), and fFerredoxin subunit nitrite reductase (FSNIR) were relatively dictateddetected. The frequency of gGlutamate synthase (GS), glutamate dehydrogenase (GDH), nNitrous oxide reductase (NOOR) and nitrate reductase(NAR) were higher in several genera than nitric oxide reductase (NIOR), NAD.P.H nitrite reductase (NNIR) and fFerredoxin subunit nitrite reductase (FSNIR) in the treatment process. The abundance of some genera associated with nitrogen metabolism and the higher frequency of genes relating nitrogen removal were mostly detected in PA and B corroborated with the high T-N removal in these two stages during the treatment process. These results indicate that a detailed nitrogen metabolism analysis of each treatment process could provide insight into the taxonomy and functions of the microbial biomass involved in nitrogen removal from the tannery wastewater.