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Convergent development of anodic bacterial communities in microbial fuel cells.

Yates MD, Kiely PD, Call DF, Rismani-Yazdi H, Bibby K, Peccia J, Regan JM, Logan BE - ISME J (2012)

Bottom Line: After 16 cycles the predominance of Geobacter spp. in anode communities was identified using 16S rRNA gene clone libraries (58±10%), fluorescent in-situ hybridization (FISH) (63±6%) and pyrosequencing (81±4%).While the clone library analysis for the underperforming UAJA3 had a significantly lower percentage of Geobacter spp. sequences (36%), suggesting that a predominance of this microbe was needed for convergent power densities, the lower percentage of this species was not verified by FISH or pyrosequencing analyses.These results show that the predominance of Geobacter spp. in acetate-fed systems was consistent with good MFC performance and independent of the inoculum source.

View Article: PubMed Central - PubMed

Affiliation: Department of Civil and Environmental Engineering, The Pennsylvania State University, University Park, PA 16802, USA.

ABSTRACT
Microbial fuel cells (MFCs) are often inoculated from a single wastewater source. The extent that the inoculum affects community development or power production is unknown. The stable anodic microbial communities in MFCs were examined using three inocula: a wastewater treatment plant sample known to produce consistent power densities, a second wastewater treatment plant sample, and an anaerobic bog sediment. The bog-inoculated MFCs initially produced higher power densities than the wastewater-inoculated MFCs, but after 20 cycles all MFCs on average converged to similar voltages (470±20 mV) and maximum power densities (590±170 mW m(-2)). The power output from replicate bog-inoculated MFCs was not significantly different, but one wastewater-inoculated MFC (UAJA3 (UAJA, University Area Joint Authority Wastewater Treatment Plant)) produced substantially less power. Denaturing gradient gel electrophoresis profiling showed a stable exoelectrogenic biofilm community in all samples after 11 cycles. After 16 cycles the predominance of Geobacter spp. in anode communities was identified using 16S rRNA gene clone libraries (58±10%), fluorescent in-situ hybridization (FISH) (63±6%) and pyrosequencing (81±4%). While the clone library analysis for the underperforming UAJA3 had a significantly lower percentage of Geobacter spp. sequences (36%), suggesting that a predominance of this microbe was needed for convergent power densities, the lower percentage of this species was not verified by FISH or pyrosequencing analyses. These results show that the predominance of Geobacter spp. in acetate-fed systems was consistent with good MFC performance and independent of the inoculum source.

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Abundance of clones with sequence identity to dominant classes in each reactor from cycle 16. UAJA3 had the lowest number of clones showing similarity to Deltaproteobacteria. The group labeled as other consists of sequences with <95% identity. Insert: the majority of the Deltaproteobacteria were Geobacter sulfurreducens.
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fig3: Abundance of clones with sequence identity to dominant classes in each reactor from cycle 16. UAJA3 had the lowest number of clones showing similarity to Deltaproteobacteria. The group labeled as other consists of sequences with <95% identity. Insert: the majority of the Deltaproteobacteria were Geobacter sulfurreducens.

Mentions: Based on the 16S rRNA gene clone libraries, during cycle 16 all reactors were found to be predominated by clones most similar to Geobacter spp. (>95% identity to Geobacter spp. with most sequences having >97% identity to G. sulfurreducens). On average, 61±6% (n=8, excluding UAJA3) of the clones were similar to Geobacter spp., except for replicate UAJA3, which had 36%. Clones distantly related to Bacteroidetes (89% identity or lower) were the second most abundant taxonomic group in all of the anode communities (11±6%, n=8), but were 36% of the clone library for the community in the UAJA3 replicate. Other sequences identified in the clone analysis were <95% similar to members of Betaproteobacteria (5±3%, n=9) and Alphaproteobacteria (2±2%, n=9) (Figure 3).


Convergent development of anodic bacterial communities in microbial fuel cells.

Yates MD, Kiely PD, Call DF, Rismani-Yazdi H, Bibby K, Peccia J, Regan JM, Logan BE - ISME J (2012)

Abundance of clones with sequence identity to dominant classes in each reactor from cycle 16. UAJA3 had the lowest number of clones showing similarity to Deltaproteobacteria. The group labeled as other consists of sequences with <95% identity. Insert: the majority of the Deltaproteobacteria were Geobacter sulfurreducens.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3475369&req=5

fig3: Abundance of clones with sequence identity to dominant classes in each reactor from cycle 16. UAJA3 had the lowest number of clones showing similarity to Deltaproteobacteria. The group labeled as other consists of sequences with <95% identity. Insert: the majority of the Deltaproteobacteria were Geobacter sulfurreducens.
Mentions: Based on the 16S rRNA gene clone libraries, during cycle 16 all reactors were found to be predominated by clones most similar to Geobacter spp. (>95% identity to Geobacter spp. with most sequences having >97% identity to G. sulfurreducens). On average, 61±6% (n=8, excluding UAJA3) of the clones were similar to Geobacter spp., except for replicate UAJA3, which had 36%. Clones distantly related to Bacteroidetes (89% identity or lower) were the second most abundant taxonomic group in all of the anode communities (11±6%, n=8), but were 36% of the clone library for the community in the UAJA3 replicate. Other sequences identified in the clone analysis were <95% similar to members of Betaproteobacteria (5±3%, n=9) and Alphaproteobacteria (2±2%, n=9) (Figure 3).

Bottom Line: After 16 cycles the predominance of Geobacter spp. in anode communities was identified using 16S rRNA gene clone libraries (58±10%), fluorescent in-situ hybridization (FISH) (63±6%) and pyrosequencing (81±4%).While the clone library analysis for the underperforming UAJA3 had a significantly lower percentage of Geobacter spp. sequences (36%), suggesting that a predominance of this microbe was needed for convergent power densities, the lower percentage of this species was not verified by FISH or pyrosequencing analyses.These results show that the predominance of Geobacter spp. in acetate-fed systems was consistent with good MFC performance and independent of the inoculum source.

View Article: PubMed Central - PubMed

Affiliation: Department of Civil and Environmental Engineering, The Pennsylvania State University, University Park, PA 16802, USA.

ABSTRACT
Microbial fuel cells (MFCs) are often inoculated from a single wastewater source. The extent that the inoculum affects community development or power production is unknown. The stable anodic microbial communities in MFCs were examined using three inocula: a wastewater treatment plant sample known to produce consistent power densities, a second wastewater treatment plant sample, and an anaerobic bog sediment. The bog-inoculated MFCs initially produced higher power densities than the wastewater-inoculated MFCs, but after 20 cycles all MFCs on average converged to similar voltages (470±20 mV) and maximum power densities (590±170 mW m(-2)). The power output from replicate bog-inoculated MFCs was not significantly different, but one wastewater-inoculated MFC (UAJA3 (UAJA, University Area Joint Authority Wastewater Treatment Plant)) produced substantially less power. Denaturing gradient gel electrophoresis profiling showed a stable exoelectrogenic biofilm community in all samples after 11 cycles. After 16 cycles the predominance of Geobacter spp. in anode communities was identified using 16S rRNA gene clone libraries (58±10%), fluorescent in-situ hybridization (FISH) (63±6%) and pyrosequencing (81±4%). While the clone library analysis for the underperforming UAJA3 had a significantly lower percentage of Geobacter spp. sequences (36%), suggesting that a predominance of this microbe was needed for convergent power densities, the lower percentage of this species was not verified by FISH or pyrosequencing analyses. These results show that the predominance of Geobacter spp. in acetate-fed systems was consistent with good MFC performance and independent of the inoculum source.

Show MeSH