The Gut Ecosystem: An Update on How Keystone Species Shape the Microbiome

Dr. Oscar Coetzee joins Dr Lara Zakaria on the Root Cause Medicine Podcast to discuss emerging research on keystone commensal organisms and how microbial communities interact within the gut ecosystem.

The conversation focuses on organisms including Akkermansia muciniphila, Faecalibacterium prausnitzii, Roseburia, Bifidobacterium longum, and Bifidobacterium adolescentis. Rather than viewing individual microbes in isolation, Dr. Coetzee describes an ecosystem model centered on cross-feeding, short-chain fatty acid production, and the intestinal environment.

The episode also notes an important context: research on next-generation commensals is still developing, meaning findings from mechanistic studies, case reports, and early clinical research offer initial insights that complement rather than replace evidence from larger randomized controlled trials. (Jan 2024) (Kern 2026)

• Keystone organisms are discussed as members of an interconnected ecosystem. The episode explores how organisms can produce metabolites or modify environmental conditions that may influence other members of the microbial community. (Belzer 2017) (Fusco 2023)
• Short-chain fatty acids are a major theme. Akkermansia, Faecalibacterium, and Roseburia are discussed in relation to acetate, propionate, and butyrate production and their potential roles within the intestinal environment. (Martin-Gallausiaux 2021)