Insights Into Metabolic Signatures and Regulatory Effect of <i>Dendrobium officinale</i> Polysaccharides in Gut Microbiota: A Comparative Study of Healthy and Diabetic Status

<i>Dendrobium officinale</i> is a kind of popular functional food to be consumed by both healthy and diabetic people. As its major constituent, <i>D. officinale</i> polysaccharide (DOP) is mainly utilized by gut microbiota. Despite distinctive gut microbiota composition between healthy and diabetic individuals, no study compared the interplay between DOP and gut microbiota under healthy and diabetic status. The current study aims to investigate and compare the metabolic signatures and regulatory potential of DOP on gut microbiota between healthy and diabetic status. Our serial in vitro fermentation investigations found that mannose in DOP was more utilized by gut microbiota under diabetic status with higher production of propanoic acid and lower production of butyric acid compared with those under healthy status. Moreover, metabolomic analyses revealed different impacts of DOP on intestinal microbial metabolites between healthy and diabetic status with upregulating taurine and downregulating 2-hydroxybutyric acid only occurring under diabetic status. Biodiversity analyses demonstrated that DOP treatment could only significantly improve the diversity of gut microbiota under diabetic status while there was no significant effect on that under healthy status. Further gut microbiota composition analyses indicated that DOP treatment could promote probiotics (<i>Dubosiella</i>, <i>Bifidobacterium</i>, and <i>Akkermansia</i>) under both healthy and diabetic status while inhibit pathogens (<i>Escherichia-Shigella</i>) only under diabetic status. In summary, our current insights into metabolic signatures and regulatory effects of DOP in the gut microbiota under healthy and diabetic status provided scientific evidence for its broad use as functional food.