Dynamics of microbial competition, commensalism and cooperation and its implications for coculture and microbiome engineering
Microbial consortium is a complex adaptive system with higher order dynamic characteristics that are not present by individual members. To accurately predict the social interactions, we formulate a set of unified unstructural kinetic models to quantitatively understand the dynamic interactions of multiple microbial species. By introducing an interaction coefficient to the growth fitness function, we analytically derived the steady state solutions for the interacting species and the substrate
... nd the substrate profile in the chemostat. We analyzed the stability of the possible co-existing states defined by competition, parasitism (predation), amensalism, commensalism and cooperation. Our model predicts that only parasitism, commensalism and cooperation could lead to stable co-existing state. We also analyzed the design constraints and operational conditions of microbial coculture with sequential metabolic reactions compartmentalized into two distinct species. Coupled with Luedeking-Piret and Michaelis-Menten equation, accumulation of metabolic precursors in one species and formation of end-product in another species could be derived and assessed. We discovered that parasitism consortia disfavor the bioconversion of intermediate to final product; and commensalism consortia could efficiently convert metabolic intermediate to final product and maintain metabolic homeostasis with a broad range of operational conditions (i.e., dilution rates); whereas cooperative consortia leads to highly nonlinear pattern of precursor accumulation and end-product formation. The underlying dynamics and emergent properties of microbial consortia may provide critical knowledge for us to engineer efficient bioconversion process, deliver effective gut therapeutics as well as elucidate probiotic-pathogen interactions in general.