Inter-species Metabolic Interactions in an In-vitro Minimal Human Gut Microbiome of Core Bacteria, 2022, Shetty et al

Abstract

Knowledge of the functional roles and interspecies interactions are crucial for improving our understanding of the human intestinal microbiome in health and disease. However, the complexity of the human intestinal microbiome and technical challenges in investigating it pose major challenges.

In this proof-of-concept study, we rationally designed, assembled and experimentally tested a synthetic Diet-based Minimal Microbiome (Db-MM) consisting of ten core intestinal bacterial species that together are capable of efficiently converting dietary fibres into short chain fatty acids (SCFAs). Despite their genomic potential for metabolic competition, all ten bacteria coexisted during growth on a mixture of dietary fibres, including pectin, inulin, xylan, cellobiose and starch. By integrated analyses of metabolite production, community composition and metatranscriptomics-based gene expression data, we identified interspecies metabolic interactions leading to production of key SCFAs such as butyrate and propionate. While public goods, such as sugars liberated from colonic fibres, are harvested by non-degraders, some species thrive by cross-feeding on energetically challenging substrates, including the butyrogenic conversion of acetate and lactate.

Using a reductionist approach in an in-vitro system combined with functional measurements, our study provides key insights into the complex interspecies metabolic interactions between core intestinal bacterial species.

Open access, https://www.nature.com/articles/s41522-022-00275-2

 

This in particular attracted my attention, given it talks of lactate and butyrate production.

"An important cross-feeding interaction observed in the human gut is conversion of lactate to butyrate and/or propionate. Of interest were the butyrate and propionate-producing A.soehngenii, C.catus and F.plautii. D,L-lactate was produced by A.rectalis and B.ovatus, both of which reached high abundances along with other carbohydrate-utilizing bacteria. The observed low abundance of A.soehngenii suggest that this organism likely follows a K-strategy to achieve coexistence as a member of the core microbiota in the human gut. The high expression of the GMM for lactate consumption by C.catus suggests that this organism likely competes with A.soehngenii for L-lactate and co-culture competition experiments can be designed in future to study this in detail."