Fig. 2: Change in substrate polymerization over time induced by enzymes for an accessible biochemical class (denoted *) in the absence of microbial uptake.
a A continuous distribution reports substrate polymerization, noted p. \({p}_{* }^{\rm{min}}\) and \({p}_{* }^{\rm{max}}\) are the minimum and maximum levels of polymerization. The \({{\mathcal{D}}}_{\rm{enz}}\) domain (blue) indicates substrate accessible to its enzymes. The \({{\mathcal{D}}}_{u}\) domain (red) indicates where the substrate is accessible to microbe uptake. Here the microbe uptake rate is nil, which explains the substrate accumulation in \({{\mathcal{D}}}_{u}\). b Two substrate cleavage factor αenz values are tested. αenz = 1 is typical of the action of endo-cleaving enzymes, which randomly disrupt any substrate bond and generate oligomers, inducing a rapid shift toward the \({{\mathcal{D}}}_{u}\) microbial uptake domain. αenz = 5 is typical of exo-cleaving enzymes attacking the substrate end-members to release small oligomers, inducing a slower shift toward \({{\mathcal{D}}}_{u}\).
