Phylogenetic distribution of 16S rRNA gene clones in soil, the organic waste-decomposing tank (the tank), control-MFCs, and MFCs. S; soil, T34; the tank on day 34, C34A; anolyte in control-MFCs on day 34, M34A; anolyte of MFCs on day 34, C34B; biofilm in control-MFCs on day 34, M34B; biofilm in MFCs on day 34, T168; the tank on day 168, C168A; anolyte in control-MFCs on day 168, M168A; anolyte in MFCs on day 168, C168B; biofilm in control-MFCs on day 168, M168B; biofilm in MFCs on day 168. The number above each bar indicates the total number of sequenced clones.