title: Analysis of the Microbial Community in an Acidic Hollow-Fiber Membrane Biofilm Reactor (Hf-MBfR) Used for the Biological Conversion of Carbon Dioxide to Methane.
abstract: Hydrogenotrophic methanogens can use gaseous substrates, such as H2 and CO2, in CH4 production. H2 gas is used to reduce CO2. We have successfully operated a hollow-fiber membrane biofilm reactor (Hf-MBfR) for stable and continuous CH4 production from CO2 and H2. CO2 and H2 were diffused into the culture medium through the membrane without bubble formation in the Hf-MBfR, which was operated at pH 4.5-5.5 over 70 days. Focusing on the presence of hydrogenotrophic methanogens, we analyzed the structure of the microbial community in the reactor. Denaturing gradient gel electrophoresis (DGGE) was conducted with bacterial and archaeal 16S rDNA primers. Real-time qPCR was used to track changes in the community composition of methanogens over the course of operation. Finally, the microbial community and its diversity at the time of maximum CH4 production were analyzed by pyrosequencing methods. Genus Methanobacterium, related to hydrogenotrophic methanogens, dominated the microbial community, but acetate consumption by bacteria, such as unclassified Clostridium sp., restricted the development of acetoclastic methanogens in the acidic CH4 production process. The results show that acidic operation of a CH4 production reactor without any pH adjustment inhibited acetogenic growth and enriched the hydrogenotrophic methanogens, decreasing the growth of acetoclastic methanogens.
authors.affiliation: Clean Energy Research Center, National Agenda Research Division, Korea Institute of Science and Technology (KIST), Seongbuk-gu, Seoul, South Korea.|Department of Environmental Engineering, University of Seoul, Dongdaemun-Ku, Seoul, South Korea.
authors.forename: Hyun Chul
authors.initials: HC
authors.lastname: Shin
authors.affiliation: Clean Energy Research Center, National Agenda Research Division, Korea Institute of Science and Technology (KIST), Seongbuk-gu, Seoul, South Korea.
authors.forename: Dong-Hun
authors.initials: DH
authors.lastname: Ju
authors.affiliation: Department of Chemical Engineering, Hanyang University, Seongdong-Ku, Seoul, South Korea.
authors.forename: Byoung Seung
authors.initials: BS
authors.lastname: Jeon
authors.affiliation: The Research Institute of Industrial Science, Hanyang University, Seongdong-Ku, Seoul, South Korea.
authors.forename: Okkyoung
authors.initials: O
authors.lastname: Choi
authors.affiliation: Department of Environmental Engineering, University of Seoul, Dongdaemun-Ku, Seoul, South Korea.
authors.forename: Hyun Wook
authors.initials: HW
authors.lastname: Kim
authors.affiliation: Clean Energy Research Center, National Agenda Research Division, Korea Institute of Science and Technology (KIST), Seongbuk-gu, Seoul, South Korea.
authors.forename: Youngsoon
authors.initials: Y
authors.lastname: Um
authors.affiliation: Department of Environmental Engineering, University of Seoul, Dongdaemun-Ku, Seoul, South Korea.
authors.forename: Dong-Hoon
authors.initials: DH
authors.lastname: Lee
authors.affiliation: Department of Chemical Engineering, Hanyang University, Seongdong-Ku, Seoul, South Korea.
authors.forename: Byoung-In
authors.initials: BI
authors.lastname: Sang
mesh_terms: D000085:Acetates / Q000737:chemistry*; D018441:Biofilms; D019149:Bioreactors / Q000382:microbiology*; D002245:Carbon Dioxide / Q000378:metabolism*; D003013:Clostridium / Q000145:classification / Q000235:genetics / Q000302:isolation & purification; D003470:Culture Media / Q000737:chemistry; D019641:DNA, Archaeal / Q000032:analysis; D004269:DNA, Bacterial / Q000032:analysis; D004275:DNA, Ribosomal / Q000032:analysis; D008697:Methane / Q000378:metabolism*; D017014:Methanobacterium / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000032:analysis; D017423:Sequence Analysis, RNA
chemical_list: D000085:Acetates; D003470:Culture Media; D019641:DNA, Archaeal; D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S; D002245:Carbon Dioxide; D008697:Methane