Microbial community structure in a dual chamber microbial fuel cell fed with brewery waste for azo dye degradation and electricity generation

The expansion in knowledge of the microbial community structure can play a vital role in the electrochemical features and operation of microbial fuel cells (MFCs). In this study, bacterial community composition in a dual chamber MFC fed with brewery waste was investigated for simultaneous electricity generation and azo dye degradation. A stable voltage was generated with a maximum power density of 305 and 269mWm �2 for brewerywaste alone(2000 mgL �1 ) and after the azo dye (200 mg L �1 ) addition, respectively. Azo dye degradation was confirmed by Fourier transform infrared spectroscopy (FT-IR) as peak corresponding to –N=N– (azo) bond disappeared in the dye metabolites. Microbial communities attached to the anode were analyzed byhigh-throughput 454 pyrosequencing of the 16S rRNA gene. Microbial community composition analysis revealed that Proteobacteria (67.3 %), Betaproteobacteria (30.8 %), and Desulfovibrio (18.3 %) were the most dominant communities at phylum, class, and genus level,respectively. Among the classifiedgenera, Desulfovibrio most likely plays a major role in electron transfer to the anode since its outer membrane contains c-type cytochromes. At the genus level, 62.3 % of all sequences belonged to the unclassified category indicating a high level of diversity of microbial groups in MFCs fed with brewery waste and azo dye. Highlights •Azo dyedegradation andstablebioelectricitygenerationwas achieved in the MFC. • Anodic biofilm was analyzed by high-throughput pyrosequencing of the 16S rRNA gene. • Desulfovibrio (18.3 %) was the dominant genus in the classified genera. • Of the genus, 62.3 % were unclassified, thereby indicating highly diverse microbes.