In vitro modelling of the structure and metabolism of the porcine caecal microbiota in response to ß-mannan exposure
The gastrointestinal microbiota plays a pivotal role in shaping host physiology and health. By selectively promoting bacteria associated with improved host health, microbiota-directed fibres offer a strategy to enhance the beneficial functions of the microbiota. In this work, we developed an in vitro fermentation system as a model to evaluate the effects of such a fibre – acetylated galactoglucomannan from Norway spruce - on the composition and functionality of porcine caecal microbial communities. We validated the in vitro experimental outcomes by comparing the response of the gut simulator to a previous in vivo feeding trial utilising the same ß-mannan fibres. Long-read sequencing with Oxford Nanopore, metatranscriptomics, and short chain fatty acid measurements were undertaken to survey microbial community dynamics and functionality. Microbial communities in real pigs and the gut simulator responded similarly to ß-mannan supplementation, with taxa like Prevotella, Catenibacterium, and Faecalibacterium increasing in abundance. Intriguingly, some taxa were observed to be more affected by ß-mannan supplementation in the simulator than in vivo. These taxa included several bacterial species that were not previously known to utilise ß-mannan, yet exhibited upregulated genes encoding carbohydrate-active enzymes involved in the degradation of this substrate.
The gastrointestinal microbiota plays a pivotal role in shaping host physiology and health. By selectively promoting bacteria associated with improved host health, microbiota-directed fibres offer a strategy to enhance the beneficial functions of the microbiota. In this work, we developed an in vitro fermentation system as a model to evaluate the effects of such a fibre – acetylated galactoglucomannan from Norway spruce - on the composition and functionality of porcine caecal microbial communities. We validated the in vitro experimental outcomes by comparing the response of the gut simulator to a previous in vivo feeding trial utilising the same ß-mannan fibres. Long-read sequencing with Oxford Nanopore, metatranscriptomics, and short chain fatty acid measurements were undertaken to survey microbial community dynamics and functionality. Microbial communities in real pigs and the gut simulator responded similarly to ß-mannan supplementation, with taxa like Prevotella, Catenibacterium, and Faecalibacterium increasing in abundance. Intriguingly, some taxa were observed to be more affected by ß-mannan supplementation in the simulator than in vivo. These taxa included several bacterial species that were not previously known to utilise ß-mannan, yet exhibited upregulated genes encoding carbohydrate-active enzymes involved in the degradation of this substrate.
Norwegian University of Life Sciences