title: Communities stimulated with ethanol to perform direct interspecies electron transfer for syntrophic metabolism of propionate and butyrate.
abstract: Direct interspecies electron transfer (DIET) has been considered as an alternative to interspecies H2 transfer (IHT) for syntrophic metabolism, but the microorganisms capable of metabolizing the key intermediates, such as propionate and butyrate, via DIET have yet to be described. A strategy of culturing the enrichments with ethanol as a DIET substrate to stimulate the communities for the syntrophic metabolism of propionate and/or butyrate was proposed in this study. The results showed that the syntrophic propionate and/or butyrate degradation was significantly improved in the ethanol-stimulated reactor when propionate/butyrate was the sole carbon source. The conductivity of the ethanol-stimulated enrichments was as 5 folds (for propionate)/76 folds (for butyrate) as that of the traditional enrichments (never ethanol fed). Microbial community analysis revealed that Geobacter species known to proceed DIET were only detected in the ethanol-stimulated enrichments. Together with the significant increase of Methanosaeta and Methanosarcina species in these enrichments, the potential DIET between Geobacter and Methanosaeta or Methanosarcina species might be established to improve the syntrophic propionate and/or butyrate degradation. Further experiments demonstrated that granular activated carbon (GAC) could improve the syntrophic metabolism of propionate and/or butyrate of the ethanol-stimulated enrichments, while almost no effects on the traditional enrichments. Also, the high H2 partial pressure could inhibit the syntrophic propionate and/or butyrate degradation of the traditional enrichments, but its effect on that of the ethanol-stimulated enrichments was negligible.
authors.affiliation: Key Laboratory of Industrial Ecology and Environmental Engineering (Dalian University of Technology), Ministry of Education, School of Environmental Science and Technology, Dalian University of Technology, Dalian, 116024, China.
authors.forename: Zhiqiang
authors.initials: Z
authors.lastname: Zhao
authors.affiliation: Key Laboratory of Industrial Ecology and Environmental Engineering (Dalian University of Technology), Ministry of Education, School of Environmental Science and Technology, Dalian University of Technology, Dalian, 116024, China. Electronic address: zhangyb@dlut.edu.cn.
authors.forename: Yaobin
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Industrial Ecology and Environmental Engineering (Dalian University of Technology), Ministry of Education, School of Environmental Science and Technology, Dalian University of Technology, Dalian, 116024, China.
authors.forename: Qilin
authors.initials: Q
authors.lastname: Yu
authors.affiliation: Beijing Key Lab for Source Control Technology of Water Pollution, Beijing Forestry University, 35 Tsinghua East Road, Beijing, 100083, China; Department of Microbiology, University of Massachusetts, Amherst, MA, 01003-9298, USA.
authors.forename: Yan
authors.initials: Y
authors.lastname: Dang
authors.affiliation: Key Laboratory of Industrial Ecology and Environmental Engineering (Dalian University of Technology), Ministry of Education, School of Environmental Science and Technology, Dalian University of Technology, Dalian, 116024, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Li
authors.affiliation: Key Laboratory of Industrial Ecology and Environmental Engineering (Dalian University of Technology), Ministry of Education, School of Environmental Science and Technology, Dalian University of Technology, Dalian, 116024, China.
authors.forename: Xie
authors.initials: X
authors.lastname: Quan
mesh_terms: D002087:Butyrates; D004583:Electrons; D000431:Ethanol; D008697:Methane / Q000378:metabolism; D011422:Propionates / Q000378:metabolism*
chemical_list: D002087:Butyrates; D011422:Propionates; D000431:Ethanol; D008697:Methane
keywords: Direct interspecies electron transfer (DIET); Geobacter species; Syntrophic metabolism of propionate and/or butyrate; Up-flow anaerobic sludge blanket (UASB)