Simultaneous fermentation of cellulose and current production with an enriched mixed culture of thermophilic bacteria in a microbial electrolysis cell

摘要

An enriched mixed culture of thermophilic (60°C)bacteria was assembled for the purpose of using cellulose to produce current in thermophilic microbialelectrolysis cells (MECs). Cellulose was fermentedinto sugars and acids before being consumed byanode-respiring bacteria (ARB) for current production. Current densities (j) were sustained at6.5 0.2 A m2 in duplicate reactors with a coulombic efficiency (CE) of 84 0.3%, a coulombic recovery (CR) of 54 11% and without production of CH4.Low-scan rate cyclic voltammetry (LSCV) revealed amid-point potential (Eka) of 0.17 V versus SHE.Pyrosequencing analysis of the V4 hypervariableregion of 16S rDNA and scanning electron microscopy present an enriched thermophilic microbialcommunity consisting mainly of the phylumFirmicutes with the Thermoanaerobacter (46 13%)and Thermincola (28 14%) genera occupying thebiofilm anode in high relative abundance and Tepidmicrobium (38 6%) and Moorella (11 8%) generapresent in high relative abundance in the bulk medium. The Thermoanaerobacter (15 16%) andBrevibacillus (21 30%) genera were also present inthe bulk medium; however, their relative abundancevaried by reactor. This study indicates that thermophilic consortia can obtain high CE and CR, whilesustaining high current densities from cellulose inMECs.