Algaebiome
Algae are a rich but unexplored source of fibers with the potential to contribute to the next generation prebiotics. The sulfated brown algae polysaccharide, fucoidan, is mainly composed of the deoxy-hexose L-fucose, which can be metabolized to 1,2-propanediol (1,2-PD) by gut microbes as a precursor of propionate. It was the aim of this study to investigate the impact of fucoidan on the fermentation capacity of the fecal microbiota and to compare it to fucose. In batch fermentations of the fecal microbiota collected from 17 donors, fucose promoted the production of propionate while no effect was observed for fucoidan and the Fucus vesiculosus-extract. H2S production was detected under all tested conditions, and levels were significantly lower in the presence of fucose in a dose-dependent manner. In the presence of high fucose levels, there was higher abundance of 1,2-PD and of lactate cross-feeders likely through additional interaction activities.  Our results highlight the limited potential of fecal microbiota to digest fucoidan. Moreover, fucose impacted fermentation capacity likely through microbial cross-feeding, which in turn might allow precise modulation of intestinal microbiota activity.