Methods for understanding microbial community structures and functions in microbial fuel cells: a review. 
Microbial fuel cells (MFCs) employ microorganisms to recover electric energy from organic matter.  However, fundamental knowledge of electrochemically active bacteria is still required to maximize MFCs power output for practical applications.  This review presents microbiological and electrochemical techniques to help researchers choose the appropriate methods for the MFCs study.  Pre-genomic and genomic techniques such as 16S rRNA based phylogeny and metagenomics have provided important information in the structure and genetic potential of electrode-colonizing microbial communities.  Post-genomic techniques such as metatranscriptomics allow functional characterizations of electrode biofilm communities by quantifying gene expression levels.  Isotope-assisted phylogenetic analysis can further link taxonomic information to microbial metabolisms.  A combination of electrochemical, phylogenetic, metagenomic, and post-metagenomic techniques offers opportunities to a better understanding of the extracellular electron transfer process, which in turn can lead to process optimization for power output.