bioRxiv2026
Microbial communities are shaped by coupled interactions between microenvironment conditions and the intracellular adaptations that emerge in response external metabolic cues. For pathogenic microbes such as Pseudomonas aeruginosa, these interactions can rapidly generate heterogeneous sub-populations that exhibit adaptations for sustaining host infection and resisting antibiotic treatment. Technological strides in -omics data collection, combined with robust computational tools like genome-scale metabolic models (GEM) for predicting cellular metabolism, have yielded promising multi-scale depictions of microbial population development in simulated spatial environments. These multi-scale model simulations help establish and evaluate mechanistic contexts for how infection-enhancing behaviors might emerge in the population or be influenced by variable perturbations in the biological system. However, the number and rigorous tuning of parameters influencing the connections between intracellular-extracellular events pose barriers when shaping simulations to different in vitro systems of interest. In this work, we present a genome-scale, metabolism-informed continuum model (GEM-CM), a computational framework for coupling a reaction-diffusion model to a surrogate GEM representation that generates metabolic rate predictions informed by flux balance analysis outputs. A key feature of GEM-CM is its application of random forest regression, or ensembles, to coarse-grain the interface connecting the GEM and reaction-diffusion models down to a small set of input metabolites methodically chosen through the random forests evaluation of feature importance. To demonstrate GEM-CMs utility, we evaluated simulation predictions against P. aeruginosa PA14 populations radially propagating in low weight percentage agar gels. In addition to biomass growth, we simulated PA14 populations producing the cytotoxic secondary metabolite pyocyanin (PCN). GEM-CM could capture PA14 growth dynamics in agar gels when ensembles were provided with three carbon source inputs describing the simulated growth media. Bacterial motility parameters and the random forest ensemble allowed GEM-CM simulations to accurately predict spatial biomass distributions for PA14 populations over time and probe their PCN production dynamics. Ensembles also demonstrated robust performance for single gene knockout conditions with GEM-CM simulation accurately capturing the partial or total biomass and PCN inhibition observed in transposon mutant screenings. When evaluating transposon mutant population development, the GEM-CM framework additionally suggested that metH may be a promising target to inhibit the spatial propagation of PA14. This works proof-of-concept applications illustrated GEM-CM utility as an early stage multi-scale modeling tool for interrogating in vitro metabolic behavior in microbial populations.