Microbial fuel cells (MFCs) have the potential for use in both waste degradation as well as energy generation. An understanding of anode chamber microbial community could contribute to optimizing these applications. The combination of stable isotope probing (SIP) and high-throughput sequencing can provide information on the activity and abundance of microorganisms while existing in mixed cultures. For this study, eight sets of MFCs anode chamber microcosms were analyzed to profile the microbial community and identify the microorganisms involved in carbon uptake from the amended substrates. The MFCs were amended with labeled (13C) or unlabeled sodium acetate and glucose and the external resistance was manipulated to two levels (10 ohms and 1000 ohms). For the sodium acetate amended MFCs, the dominant phyla were the Proteobacteria, Bacteroidetes, Firmicutes, and Actinobacteria. For the glucose amended MFCs, similar dominant phyla were detected, except Actinobacteria. Through comparing enrichment factors between the labeled and unlabeled fractions, 14 phylotypes were found to be responsible for label uptake in the sodium acetate amended MFCs and 13 phylotypes were responsible in the glucose amended MFCs. Among these, unclassified Parachlamydiaceae (Chlamydia), Azospirillum (Proteobacteria), and unclassified Rhodocyclaceae (Proteobacteria) were the primary phylotypes uptaking the labeled carbon. To my knowledge, this is the first study to combine SIP with high-throughput sequencing to identify the active microorganisms in MFCs.
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