caa a22 4500 46582353X CHVBK 20180323112142.0 cr unu---uuuuu 170327e19900401xx s 000 0 eng 10.1007/BF00170577 doi (NATIONALLICENCE)springer-10.1007/BF00170577 Thermodynamic evidence of trophic microniches in methanogenic granular sludge-bed reactors [Elektronische Daten] [André Pauss, Réjean Samson, Serge Guiot] Summary: The Gibbs free energy changes in methanogenic granular biomass from sludge-bed reactors were evaluated using the in situ concentrations and partial pressures of metabolites during the metabolism of acetate, hydrogen, formate and propionate. Based on mass balance calculations it appeared that the degradation of propionate into acetate, hydrogen and bicarbonate was endergonic, even if propionate was effectively degraded. On the other hand, the methane-producing reactions, both from acetate and from hydrogen plus bicarbonate, were found to be exergonic and the free energy change was sufficient for the formation of ATP. Formate was detected in only one of the two reactors. When formate, instead of hydrogen, was considered as the electron carrier between propionate-degrading and methanogenic bacteria, similar thermodynamic results were obtained. The existence of trophic microniches in the granular biomass is suggested to explain propionate degradation even though the Gibbs free energy change in the liquid surrounding the granules was positive. Hence, to make propionate degradation exergonic the dissolved hydrogen concentration surrounding the propionate-degrading bacteria would have to be about 30 times lower than in the free liquid. Springer-Verlag, 1990 Pauss André Biotechnology Research Institute, National Research Council Canada, 6100 Ave. Royalmount, H4P 2R2, Montréal, Québec, Canada aut Samson Réjean Biotechnology Research Institute, National Research Council Canada, 6100 Ave. Royalmount, H4P 2R2, Montréal, Québec, Canada aut Guiot Serge Biotechnology Research Institute, National Research Council Canada, 6100 Ave. Royalmount, H4P 2R2, Montréal, Québec, Canada aut Applied Microbiology and Biotechnology Springer-Verlag 33/1(1990-04-01), 88-92 0175-7598 33:1<88 1990 33 253 https://doi.org/10.1007/BF00170577 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00170577 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Pauss André Biotechnology Research Institute, National Research Council Canada, 6100 Ave. Royalmount, H4P 2R2, Montréal, Québec, Canada aut NATIONALLICENCE 700 1- Samson Réjean Biotechnology Research Institute, National Research Council Canada, 6100 Ave. Royalmount, H4P 2R2, Montréal, Québec, Canada aut NATIONALLICENCE 700 1- Guiot Serge Biotechnology Research Institute, National Research Council Canada, 6100 Ave. Royalmount, H4P 2R2, Montréal, Québec, Canada aut NATIONALLICENCE 773 0- Applied Microbiology and Biotechnology Springer-Verlag 33/1(1990-04-01), 88-92 0175-7598 33:1<88 1990 33 253 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer