Responses of the colonic microbiota and metabolites during fermentation of alginate oligosaccharides in normal individuals: An in vitro and in vivo study

Abstract

Alginate oligosaccharides (AOS) have been reported to promote gut microbiota and sperm quality in male mice treated with busulfan. However, there is little evidence that AOS is directly influenced colonic microbiota and metabolites in healthy males. We administered AOS to rats by gavage for four weeks and observed significant regulation in the abundance of microbiota, including Bifidobacterium, Bacteroides, Anaerosptipes, Akkermania, Anaeroplasma, and Blautia, in the colon of male rats. In addition, AOS intervention significantly modulated colonic metabolites (butyrate, acetate, cytarabine, glycolic acid, and 3-hydroxybutyric acid) in healthy male rats. By contrast, there were no significant differences in the colonic metabolites of female rats. Further, we performed in vitro fermentation experiments using healthy male fecal samples and verified that AOS significantly increased the levels of Bacteroides, Anaerosptipes, and Blautia and promoted the content of butyrate and acetate in the fermentation broth. We also observed that these microbiotas were significantly positively correlated with cytarabine, 3-hydroxybutyric acid, and glycolic acid. This study provides new evidence that AOS is a potential prebiotic in male functional foods.