Fig. 1: The illustration conceptualizes the dynamics of microbial interaction networks influencing anaerobic degradation processes.
A The anaerobic degradation process of sucrose by three primary trophic groups involves a series of steps. First, a fermentation step is mediated by fermentative bacteria (FB, yellow circle). Subsequently, a syntrophic oxidation step for fermentation products such as butyrate (Bu) and propionate (Pr) is responsible for syntrophic bacteria (SB, green circle). Finally, a methane-producing step from the methanogenic precursors, hydrogen/carbon dioxide (H2/CO2) and acetate (Ac), is facilitated by methanogenic archaea (MA, red circle). B As the microbial communities in the reactor undergo succession after start-up, dynamic changes in microbial interactions among various trophic groups affect system performance (substrate catabolism) and community assembly over time. Each of these components can be described conceptually using an equation expressing the microbial growth, dX/dt, as a function of microbial growth yield (Y), substrate catabolism (dS/dt), time-varying microbial interactions of various trophic groups (finteraction), and the environmental factors (fenv). IS, the interaction strength of positive (blue arrow) and negative (red arrow) edges; VFAs, volatile fatty acids; ΔG′, Gibbs free energy change for the reaction. Assuming constant environmental factors, changes in microbial growth or abundance are determined by both substrate catabolism and microbial interactions with time.
