Establishment of functional rumen bacterial consortia (FRBC) for simultaneous biohydrogen and bioethanol production from lignocellulose

Abstract

For simultaneous saccharification and fermentation of cellulosic bioresources to biofuels, a stable rumen-mimicking bacterial consortium was established and maintained by sub-culturing and is referred to here as the “Functional Rumen Bacterial Consortium” (FRBC). The microbial community was analyzed by denaturing gradient gel electrophoresis, which contained dominant species such as Clostridium xylanolyticum, Clostridium papyrosolvens, Clostridium beijerinckii, Clostridium puniceum, Clostridium putrifaciens, and Ruminococcus sp. These predominant Clostridial strains showed potential in converting lignocellulosic material into bio-hydrogen and bio-fuels. The Clostridial strains with 16S rRNA sequences identical to the DGGE profile were isolated from FRBC. The isolate C. puniceum strain Ru6 exhibited xylanase and pectinase activity and higher hydrogen productivity and was thus chosen as the partner strain for ethanol production with C. xylanolyticum Ru15, which showed additional endoglucanase activity. A co-culture approach was used to reconstruct the FRBC with Ru6 and Ru15, and the productivities of hydrogen and ethanol were comparable to that of the FRBC. These results demonstrate the potential of a biologically inspired rumen-mimic microbial community to produce cellulosic bio-fuels.