title: Quantifying the effects of the division of labor in metabolic pathways.
abstract: Division of labor is commonly observed in nature. There are several theories that suggest diversification in a microbial community may enhance stability and robustness, decrease concentration of inhibitory intermediates, and increase efficiency. Theoretical studies to date have focused on proving when the stable co-existence of multiple strains occurs, but have not investigated the productivity or biomass production of these systems when compared to a single 'super microbe' which has the same metabolic capacity. In this work we prove that if there is no change in the growth kinetics or yield of the metabolic pathways when the metabolism is specialized into two separate microbes, the biomass (and productivity) of a binary consortia system is always less than that of the equivalent monoculture. Using a specific example of Escherichia coli growing on a glucose substrate, we find that increasing the growth rates or substrate affinities of the pathways is not sufficient to explain the experimentally observed productivity increase in a community. An increase in pathway efficiency (yield) in specialized organisms provides the best explanation of the observed increase in productivity.
authors.affiliation: Mathematical Sciences, Montana State University, Bozeman, MT 59715, United States; Chemical and Biological Engineering, Montana State University, Bozeman, MT 59715, United States. Electronic address: e.p.harvey@massey.ac.nz.
authors.forename: Emily
authors.initials: E
authors.lastname: Harvey
authors.affiliation: Chemical and Biological Engineering, Montana State University, Bozeman, MT 59715, United States. Electronic address: jeffrey.heys@coe.montana.edu.
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Heys
authors.affiliation: Mathematical Sciences, Montana State University, Bozeman, MT 59715, United States. Electronic address: gedeon@math.montana.edu.
authors.forename: Tomáš
authors.initials: T
authors.lastname: Gedeon
mesh_terms: D000220:Adaptation, Biological / Q000502:physiology*; D018533:Biomass; D003198:Computer Simulation; D004926:Escherichia coli / Q000254:growth & development / Q000378:metabolism; D005947:Glucose / Q000378:metabolism; D053858:Metabolic Networks and Pathways / Q000502:physiology*; D059013:Microbial Consortia / Q000502:physiology*; D008954:Models, Biological; D013045:Species Specificity
chemical_list: D005947:Glucose
keywords: Chemostat; Cross-feeding; Mathematical modeling; Microbial ecology; Syntrophic consortia