title: Microbial catabolic activities are naturally selected by metabolic energy harvest rate.
abstract: The fundamental trade-off between yield and rate of energy harvest per unit of substrate has been largely discussed as a main characteristic for microbial established cooperation or competition. In this study, this point is addressed by developing a generalized model that simulates competition between existing and not experimentally reported microbial catabolic activities defined only based on well-known biochemical pathways. No specific microbial physiological adaptations are considered, growth yield is calculated coupled to catabolism energetics and a common maximum biomass-specific catabolism rate (expressed as electron transfer rate) is assumed for all microbial groups. Under this approach, successful microbial metabolisms are predicted in line with experimental observations under the hypothesis of maximum energy harvest rate. Two microbial ecosystems, typically found in wastewater treatment plants, are simulated, namely: (i) the anaerobic fermentation of glucose and (ii) the oxidation and reduction of nitrogen under aerobic autotrophic (nitrification) and anoxic heterotrophic and autotrophic (denitrification) conditions. The experimentally observed cross feeding in glucose fermentation, through multiple intermediate fermentation pathways, towards ultimately methane and carbon dioxide is predicted. Analogously, two-stage nitrification (by ammonium and nitrite oxidizers) is predicted as prevailing over nitrification in one stage. Conversely, denitrification is predicted in one stage (by denitrifiers) as well as anammox (anaerobic ammonium oxidation). The model results suggest that these observations are a direct consequence of the different energy yields per electron transferred at the different steps of the pathways. Overall, our results theoretically support the hypothesis that successful microbial catabolic activities are selected by an overall maximum energy harvest rate.
authors.affiliation: Institute Centre for Water and Environment (iWATER), Department of Chemical and Environmental Engineering (CEE), Masdar Institute of Science and Technology, Abu Dhabi, UAE.|Department of Chemical Engineering, Institute of Technology, University of Santiago de Compostela, Santiago de Compostela, Galicia, Spain.
authors.forename: Rebeca
authors.initials: R
authors.lastname: González-Cabaleiro
authors.affiliation: Institute Centre for Water and Environment (iWATER), Department of Chemical and Environmental Engineering (CEE), Masdar Institute of Science and Technology, Abu Dhabi, UAE.
authors.forename: Irina D
authors.initials: ID
authors.lastname: Ofiţeru
authors.affiliation: Department of Chemical Engineering, Institute of Technology, University of Santiago de Compostela, Santiago de Compostela, Galicia, Spain.
authors.forename: Juan M
authors.initials: JM
authors.lastname: Lema
authors.affiliation: Institute Centre for Water and Environment (iWATER), Department of Chemical and Environmental Engineering (CEE), Masdar Institute of Science and Technology, Abu Dhabi, UAE.
authors.forename: Jorge
authors.initials: J
authors.lastname: Rodríguez
mesh_terms: D000332:Aerobiosis; D000693:Anaerobiosis; D052818:Autotrophic Processes; D001419:Bacteria / Q000737:chemistry / Q000378:metabolism*; D018533:Biomass; D019149:Bioreactors / Q000382:microbiology*; D058440:Denitrification; D004734:Energy Metabolism; D007700:Kinetics; D008697:Methane / Q000378:metabolism; D058465:Nitrification; D009584:Nitrogen / Q000378:metabolism; D010084:Oxidation-Reduction; D062065:Wastewater / Q000382:microbiology*
chemical_list: D008697:Methane; D009584:Nitrogen; D062065:Wastewater