Open AccessSimultaneous fermentation of cellulose and current production with an enriched mixed culture of thermophilic bacteria in a microbial electrolysis cell
Author(s) -
Lusk Bradley G.,
Colin Alexandra,
Parameswaran Prathap,
Rittmann Bruce E.,
Torres Cesar I.
Publication year - 2018
Publication title -
microbial biotechnology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.287
H-Index - 74
ISSN - 1751-7915
DOI - 10.1111/1751-7915.12733
Subject(s) - thermophile , cellulose , firmicutes , food science , bacteria , fermentation , microbial electrolysis cell , biology , faraday efficiency , acidogenesis , electrolysis , chemistry , microbiology and biotechnology , biochemistry , microbial fuel cell , anode , 16s ribosomal rna , anaerobic digestion , ecology , electrode , electrolyte , genetics , methane
Summary An enriched mixed culture of thermophilic (60°C) bacteria was assembled for the purpose of using cellulose to produce current in thermophilic microbial electrolysis cells ( MEC s). Cellulose was fermented into sugars and acids before being consumed by anode‐respiring bacteria ( ARB ) for current production. Current densities ( j ) were sustained at 6.5 ± 0.2 A m −2 in duplicate reactors with a coulombic efficiency ( CE ) of 84 ± 0.3%, a coulombic recovery ( CR ) of 54 ± 11% and without production of CH 4 . Low‐scan rate cyclic voltammetry ( LSCV ) revealed a mid‐point potential ( E ka ) of −0.17 V versus SHE . Pyrosequencing analysis of the V4 hypervariable region of 16S rDNA and scanning electron microscopy present an enriched thermophilic microbial community consisting mainly of the phylum Firmicutes with the Thermoanaerobacter (46 ± 13%) and Thermincola (28 ± 14%) genera occupying the biofilm anode in high relative abundance and Tepidmicrobium (38 ± 6%) and Moorella (11 ± 8%) genera present in high relative abundance in the bulk medium. The Thermoanaerobacter (15 ± 16%) and Brevibacillus (21 ± 30%) genera were also present in the bulk medium; however, their relative abundance varied by reactor. This study indicates that thermophilic consortia can obtain high CE and CR , while sustaining high current densities from cellulose in MEC s.