Characterization of electrochemically active bacteria in microbial fuel cells by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

S.F.Y. Li, L. Zhang, Y. Gao, L. Lai
National University of Singapore,

Keywords: electrochemically active bacteria, microbial fuel cell, electricigens, domestic wastewater


Electrochemically active bacteria (EAB) that are capable of producing electricity from renewable biomass and organic wastes are of particular interest in recent years. Methods for selective enrichment, accurate identification and easy acquisition of EAB fingerprints for phylogenetic characterization would facilitate utilization of these bioenergy-producing species in practical environmental engineering applications. Electricigens were selectively enriched from domestic wastewater in a microbial fuel cell (MFC). Mass fingerprints of EAB were obtained by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF/TOF MS) and species-specific analyses were completed by using the Spectral ARchive and Microbial Identification System (SARAMIS). EAB could be discriminated by clustering of MALDI-TOF/TOF MS results. Different species in mixtures originating from domestic sewage could be identified unambiguously at 99.90% confidence. By using agglomerative clustering algorithm to compute spectral similarity and diversity, a dendrogram was constructed to illustrate the phylogenetic relationships for EAB on the basis of mass spectral analyses. An integrated method based on MFC-enrichment, agar-cultivation and MALDI-TOF/TOF MS identification of whole-cell extracted proteins has been proved to be a simple, rapid and reliable approach for rapid identification and routine inspection of EAB. Mixed phyla can be analyzed at species level to provide phylogenetic information on the highly efficient bacteria generating electricity from domestic wastewater.