The membraneless bioelectrochemical reactor stimulates hydrogen fermentation by inhibiting methanogenic archaea
- 492 Downloads
The membraneless bioelectrochemical reactor (Ml-BER) is useful for dark hydrogen fermentation. The effect of the electrochemical reaction on microorganisms in the Ml-BER was investigated using glucose as the substrate and compared with organisms in a membraneless non-bioelectrochemical reactor (Ml-NBER) and bioelectrochemical reactor (BER) with a proton exchange membrane. The potentials on the working electrode of the Ml-BER and BER with membrane were regulated to −0.9 V (versus Ag/AgCl) to avoid water electrolysis with a carbon electrode. The Ml-BER showed suppressed methane production (19.8 ± 9.1 mg-C·L−1·day−1) and increased hydrogen production (12.6 ± 3.1 mg-H·L−1·day−1) at pHout 6.2 ± 0.1, and the major intermediate was butyrate (24.9 ± 2.4 mM), suggesting efficient hydrogen fermentation. In contrast, the Ml-NBER showed high methane production (239.3 ± 17.9 mg-C·L−1·day−1) and low hydrogen production (0.2 ± 0.0 mg-H·L−1·day−1) at pHout 6.3 ± 0.1. In the cathodic chamber of the BER with membrane, methane production was high (276.3 ± 20.4 mg-C·L−1·day−1) (pHout, 7.2 ± 0.1). In the anodic chamber of the BER with membrane (anode-BER), gas production was low because of high lactate production (43.6 ± 1.7 mM) at pHout 5.0 ± 0.1. Methanogenic archaea were not detected in the Ml-BER and anode-BER. However, Methanosarcina sp. and Methanobacterium sp. were found in Ml-NBER. Prokaryotic copy numbers in the Ml-BER and Ml-NBER were similar, as were the bacterial community structures. Thus, the electrochemical reaction in the Ml-BER affected hydrogenotrophic and acetoclastic methanogens, but not the bacterial community.
KeywordsHydrogen Fermentation Bioelectrochemical system Microbial community Methanogen
This research was supported in part by the New Energy and Industrial Technology Development Organization (NEDO), Japan, and a Grant-in-Aid for Young Scientists (B) (24780067). We thank Yumi Kotake for her help.
- Ben Hania W, Godbane R, Postec A, Hamdi M, Ollivier B, Fardeau ML (2012) Isolation and characterization of Defluviitoga tunisiensis gen. nov, sp. nov., a novel thermophilic bacterium pertaining to the order Thermotogales, isolated from a mesothermic anaerobic reactor treating cheese whey in Tunisia. Int J Syst Evol Microbiol 62(Pt 6):1377–1382. doi: 10.1099/ijs.0.033720-0 PubMedCrossRefGoogle Scholar
- Hoover SR, Porges N (1952) Assimilation of dairy wastes by activated sludge. II. The equation of synthesis and oxygen utilization. Sewage Ind Wastes 24:306–312Google Scholar
- Lane DJ (1991) 16S/23S rRNA sequencing. In: Stackebrandt E, Goodfellow M (eds) Nucleic acid techniques in bacterial systematics. Wiley, New York, pp 115–175Google Scholar
- Luo G, Karakashev D, Xie L, Zhou Q, Angeridaki I (2011) Long-term effect of inoculum pretreatment on fermentative hydrogen production by repeated batch cultivations: homoacetogenesis and methanogenesis as competitors to hydrogen production. Biotechnol Bioeng 108:1816–1827PubMedCrossRefGoogle Scholar