Microbial protein metabolism in the monogastric gastrointestinal tract: a review

Dietary and endogenous protein that become available for the microbiota in the hindgut can be metabolized via different routes. They can become building blocks for the microbial cells or enter different catabolic pathways. Protein degradation via fermentation pathways is seen as a non-preferred route as it results in the formation and release of metabolites that can interfere with biological systems in the host and can have deleterious outcomes. Reducing protein fermentation and guiding the metabolism towards less toxic end-products might be possible targets for improving host health. To do so, more knowledge on factors manipulating the process of microbial protein metabolism, including on substrate availability, microbial composition and segmental differences in the hindgut, is required.