TY - JOUR
T1 - Microbial community structure in a biofilm anode fed with a fermentable substrate
T2 - The significance of hydrogen scavengers
AU - Parameswaran, Prathap
AU - Zhang, Husen
AU - Torres, Cesar
AU - Rittmann, Bruce
AU - Krajmalnik-Brown, Rosa
PY - 2010/1/1
Y1 - 2010/1/1
N2 - We compared the microbial community structures that developed in the biofilm anode of two microbial electrolysis cells fed with ethanol, a fermentable substrate - one where methanogenesis was allowed and another in which it was completely inhibited with 2-bromoethane sulfonate. We observed a three-way syntrophy among ethanol fermenters, acetate-oxidizing anode-respiring bacteria (ARB), and a H2 scavenger. When methanogenesis was allowed, H2-oxidizing methanogens were the H2 scavengers, but when methanogenesis was inhibited, homo-acetogens became a channel for electron flow from H2 to current through acetate. We established the presence of homo-acetogens by two independent molecular techniques: 16S rRNA gene based pyrosequencing and a clone library from a highly conserved region in the functional gene encoding formyltetrahydrofolate synthetase in homo-acetogens. Both methods documented the presence of the homo-acetogenic genus, Acetobacterium, only with methanogenic inhibition. Pyrosequencing also showed a predominance of ethanol-fermenting bacteria, primarily represented by the genus Pelobacter. The next most abundant group was a diverse community of ARB, and they were followed by H2-scavenging syntrophic partners that were either H2-oxidizing methanogens or homo-acetogens when methanogenesis was suppressed. Thus, the community structure in the biofilm anode and suspension reflected the electron-flow distribution and H2-scavenging mechanism.
AB - We compared the microbial community structures that developed in the biofilm anode of two microbial electrolysis cells fed with ethanol, a fermentable substrate - one where methanogenesis was allowed and another in which it was completely inhibited with 2-bromoethane sulfonate. We observed a three-way syntrophy among ethanol fermenters, acetate-oxidizing anode-respiring bacteria (ARB), and a H2 scavenger. When methanogenesis was allowed, H2-oxidizing methanogens were the H2 scavengers, but when methanogenesis was inhibited, homo-acetogens became a channel for electron flow from H2 to current through acetate. We established the presence of homo-acetogens by two independent molecular techniques: 16S rRNA gene based pyrosequencing and a clone library from a highly conserved region in the functional gene encoding formyltetrahydrofolate synthetase in homo-acetogens. Both methods documented the presence of the homo-acetogenic genus, Acetobacterium, only with methanogenic inhibition. Pyrosequencing also showed a predominance of ethanol-fermenting bacteria, primarily represented by the genus Pelobacter. The next most abundant group was a diverse community of ARB, and they were followed by H2-scavenging syntrophic partners that were either H2-oxidizing methanogens or homo-acetogens when methanogenesis was suppressed. Thus, the community structure in the biofilm anode and suspension reflected the electron-flow distribution and H2-scavenging mechanism.
KW - Anode respiring bacteria
KW - Homo-acetogenesis
KW - Methanogenesis
KW - Microbial electrolysis cells
KW - Syntrophy
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U2 - 10.1002/bit.22508
DO - 10.1002/bit.22508
M3 - Article
C2 - 19688868
AN - SCOPUS:73949088543
VL - 105
SP - 69
EP - 78
JO - Biotechnology and Bioengineering
JF - Biotechnology and Bioengineering
SN - 0006-3592
IS - 1
ER -