Print Email Facebook Twitter Kinetic and thermodynamic control of butyrate conversion in non-defined methanogenic communities Title Kinetic and thermodynamic control of butyrate conversion in non-defined methanogenic communities Author Junicke, H. Van Loosdrecht, M.C.M. Kleerebezem, R. Faculty Applied Sciences Department BT/Biotechnology Date 2015-09-25 Abstract Many anaerobic conversions proceed close to thermodynamic equilibrium and the microbial groups involved need to share their low energy budget to survive at the thermodynamic boundary of life. This study aimed to investigate the kinetic and thermodynamic control mechanisms of the electron transfer during syntrophic butyrate conversion in non-defined methanogenic communities. Despite the rather low energy content of butyrate, results demonstrate unequal energy sharing between the butyrate-utilizing species (17 %), the hydrogenotrophic methanogens (9–10 %), and the acetoclastic methanogens (73–74 %). As a key finding, the energy disproportion resulted in different growth strategies of the syntrophic partners. Compared to the butyrate-utilizing partner, the hydrogenotrophic methanogens compensated their lower biomass yield per mole of electrons transferred with a 2-fold higher biomass-specific electron transfer rate. Apart from these thermodynamic control mechanisms, experiments revealed a ten times lower hydrogen inhibition constant on butyrate conversion than proposed by the Anaerobic Digestion Model No. 1, suggesting a much stronger inhibitory effect of hydrogen on anaerobic butyrate conversion. At hydrogen partial pressures exceeding 40 Pa and at bicarbonate limited conditions, a shift from methanogenesis to reduced product formation was observed which indicates an important role of the hydrogen partial pressure in redirecting electron fluxes towards reduced products such as butanol. The findings of this study demonstrate that a careful consideration of thermodynamics and kinetics is required to advance our current understanding of flux regulation in energy-limited syntrophic ecosystems. Subject syntrophic butyrate conversioninterspecies electron transferhydrogen inhibitionthermodynamic controlkinetic controlreduced product formation To reference this document use: http://resolver.tudelft.nl/uuid:4766c243-e8bf-4e09-a927-965373fbe541 Publisher Springer ISSN 0175-7598 Source https://doi.org/10.1007/s00253-015-6971-9 Source Applied Microbiology and Biotechnology, 100 (2), 2016 Part of collection Institutional Repository Document type journal article Rights (c) 2015 The Author(s)This article is published with open access at Springerlink.com Files PDF Junicke_2015.pdf 902.72 KB Close viewer /islandora/object/uuid:4766c243-e8bf-4e09-a927-965373fbe541/datastream/OBJ/view