(194j) Byproduct Cross Feeding and Community Stability in an in silico Biofilm Model of the Gut Microbiome
Gut microbiome function is usually robust to dietary changes and other perturbations that alter species composition and SCFA synthesis. Correspondingly, metagenomic studies have shown wide variations in microbiota diversity and composition within healthy human populations. However, large perturbations in susceptible individuals can result in long-term microbiome alteration. Many diseases are associated with the gut flora being perturbed from their normal state through a poorly understood process known as dysbiosis. The role of species interactions in maintaining healthy community function or promoting dysbiosis are poorly understood. Despite some recent progress, the types of species interactions required for stable community dynamics in biofilm communities where nutrient gradients provide niches for different metabolic lifestyles have not been elucidated.
We developed a biofilm metabolic model of a very simple gut microbiome community consisting of a representative bacteroidete (Bacteroides thetaiotaomicron), firmicute (Faecalibacterium prausnitzii) and proteobacterium (Escherichia coli) to investigate the putative role of metabolic byproduct cross feeding between species on community stability, robustness and flexibility. The model predicted co-existence of the three species only if four essential cross-feeding relationships were present. We found that cross feeding allowed co-existence to be robustly maintained for large variations in biofilm thickness and nutrient levels. Our model predictions provide new insights into the impact of byproduct cross feeding and yield experimentally testable hypotheses about gut microbiome community stability.