Abstract
A hydrogen utilizing exoelectrogenic bacterium (Geobacter sulfurreducens) was compared to both a nonhydrogen oxidizer (Geobacter metallireducens) and a mixed consortium in order to compare the hydrogen production rates and hydrogen recoveries of pure and mixed cultures in microbial electrolysis cells (MECs). At an applied voltage of 0.7 V, both G. sulfurreducens and the mixed culture generated similar current densities (ca. 160 A/m3), resulting in hydrogen production rates of ca. 1.9 m3 H2/m 3/day, whereas G. metallireducens exhibited lower current densities and production rates of 110 ± 7 A/m3 and 1.3 ± 0.1 m3 H2/m3/day, respectively. Before methane was detected in the mixed-culture MEC, the mixed consortium achieved the highest overall energy recovery (relative to both electricity and substrate energy inputs) of 82% ± 8% compared to G. sulfurreducens (77% ± 2%) and G. metallireducens (78% ± 5%), due to the higher coulombic efficiency of the mixed consortium. At an applied voltage of 0.4 V, methane production increased in the mixed-culture MEC and, as a result, the hydrogen recovery decreased and the overall energy recovery dropped to 38% ± 16% compared to 80% ± 5% for G. sulfurreducens and 76% ± 0% for G. metallireducens. Internal hydrogen recycling was confirmed since the mixed culture generated a stable current density of 31 ± 0 A/m3 when fed hydrogen gas, whereas G. sulfurreducens exhibited a steady decrease in current production. Community analysis suggested that G. sulfurreducens was predominant in the mixed-culture MEC (72% of clones) despite its relative absence in the mixed-culture inoculum obtained from a microbial fuel cell reactor (2% of clones). These results demonstrate that Geobacter species are capable of obtaining similar hydrogen production rates and energy recoveries as mixed cultures in an MEC and that high coulombic efficiencies in mixed culture MECs can be attributed in part to the recycling of hydrogen into current. Copyright © 2009, American Society for Microbiology. All Rights Reserved.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 7579-7587 |
| Number of pages | 9 |
| Journal | Applied and Environmental Microbiology |
| Volume | 75 |
| Issue number | 24 |
| DOIs | |
| State | Published - Oct 9 2009 |
| Externally published | Yes |
Bibliographical note
KAUST Repository Item: Exported on 2020-10-01Acknowledged KAUST grant number(s): KUS-I1-003-13
Acknowledgements: We thank D. W. Jones for help with the analytical measurements;M. L. Hazen for assistance with the SEM imaging; and the Penn StateGenomics Core Facility, University Park, PA, for DNA sequencing.This research was funded by the American Society of EngineeringEducation National Defense Science and Engineering Graduate Fellowship,the National Science Foundation Graduate Research FellowshipProgram, a National Water Research Institute Ronald B. LinskyFellowship, and award KUS-I1-003-13 from King Abdullah Universityof Science and Technology.
This publication acknowledges KAUST support, but has no KAUST affiliated authors.
