In this study, we determined the microbial communities present in a PMFC rhizosphere and localised the active EAB in the rhizosphere and on the electrode of the PMFC. Ad- ditionally, we investigated the electron donor and electron pathways in the PMFC. We used 454 technology to se- quence 16S rRNA gene amplicon libraries from bacteria and archaea. To prove the relevance of dominant pyloge- netic groups and to localise those bacteria and archaea, fluorescent in situ hybridisation (FISH) in combination with confocal laser scanning microscopy (CLSM) was performed in samples of high-current-generating and low-current- generating Glyceria maxima (reed mannagrass) PMFC.