title: Kinetics of Substrate Biodegradation under the Cumulative Effects of Bioavailability and Self-Inhibition.
abstract: Microbial degradation is an important process in many environments controlling for instance the cycling of nutrients or the biodegradation of contaminants. At high substrate concentrations toxic effects may inhibit the degradation process. Bioavailability limitations of a degradable substrate can therefore either improve the overall dynamics of degradation by softening the contaminant toxicity effects to microorganisms, or slow down the biodegradation by reducing the microbial access to the substrate. Many studies on biodegradation kinetics of a self-inhibitive substrate have mainly focused on physiological responses of the bacteria to substrate concentration levels without considering the substrate bioavailability limitations rising from different geophysical and geochemical dynamics at pore-scale. In this regard, the role of bioavailability effects on the kinetics of self-inhibiting substrates is poorly understood. In this study, we theoretically analyze this role and assess the interactions between self-inhibition and mass transfer-limitations using analytical/numerical solutions, and show the findings practical relevance for a simple model scenario. Although individually self-inhibition and mass-transfer limitations negatively impact biodegradation, their combined effect may enhance biodegradation rates above a concentration threshold. To our knowledge, this is the first theoretical study describing the cumulative effects of the two mechanisms together.
authors.affiliation: †Department of Environmental Microbiology, UFZ - Helmholtz Centre for Environmental Research, Permoserstraße 15, 04318 Leipzig, Germany.|‡Institute of Groundwater Ecology, Helmholtz Zentrum München, Ingolstädter Landstr. 1, 85764 Neuherberg, Germany.
authors.forename: Mehdi
authors.initials: M
authors.lastname: Gharasoo
authors.affiliation: †Department of Environmental Microbiology, UFZ - Helmholtz Centre for Environmental Research, Permoserstraße 15, 04318 Leipzig, Germany.
authors.forename: Florian
authors.initials: F
authors.lastname: Centler
authors.affiliation: §Department of Earth and Environmental Sciences, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada.
authors.forename: Philippe
authors.initials: P
authors.lastname: Van Cappellen
authors.affiliation: †Department of Environmental Microbiology, UFZ - Helmholtz Centre for Environmental Research, Permoserstraße 15, 04318 Leipzig, Germany.
authors.forename: Lukas Y
authors.initials: LY
authors.lastname: Wick
authors.affiliation: †Department of Environmental Microbiology, UFZ - Helmholtz Centre for Environmental Research, Permoserstraße 15, 04318 Leipzig, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Thullner
mesh_terms: D000465:Algorithms; D001419:Bacteria / Q000378:metabolism*; D001673:Biodegradation, Environmental; D001682:Biological Availability; D007700:Kinetics; D008962:Models, Theoretical