Adaptation of metabolite leakiness leads to symbiotic chemical exchange and to a resilient microbial ecosystem
Fig 3
Example of symbiosis with metabolic exchange via the environment.
(A) An example of randomly generated networks with n = 10. The enzyme labeled on each arrow catalyzes the conversion of the metabolite at the arrowtail to the metabolite or enzyme at the arrowhead. Among n chemicals, chemicals 1 and nenzyme = 2 are enzymes (green squares) and the nutrient chemical 0 and chemicals nenzyme + 1 = 3 to n − 1 = 9 are metabolites (orange circles). The leak-advantage metabolites in isolation conditions (chemicals 3–5, 7, and 9) are highlighted by pink. See also S3(B) Fig for the network of cell species B in panels (C) and (D). (B) Time series of the number of coexisting species through successful invasions by new species and the growth rate of coexisting cell species. (C) Plot of leakage (blue) and uptake (red) fluxes of non-nutrient chemicals from each cell species A-F. (D) Structure of metabolic exchange among six cell species that have different growth rates in isolation. The vertical axis represents the growth rate of each cell species α in isolation, . Cyan and pink arrows indicate the leakage and uptake of each chemical component, respectively. Symbiosis among multiple species increases the growth rate to μsymbiosis (as indicated on the top), which is higher than the growth rate of each cell species in isolation,
. In the numerical simulations in (B)-(D), the parameters were set to
.