Identification and characterization of an isomaltooligosaccharide utilizing α-glucosidase from the resistant-starch...

Ruminococcoides is a genus abundant in the human colon and plays a key role in carbohydrate metabolism. These microorganisms can utilize a variety of substrates for growth in the gut, but their metabolic characteristics toward dietary sugars remain poorly characterized. In our previous study, we isolated Ruminococcoides bili FMB-J6 from human feces and identified a unique glucosidase with the potential to degrade prebiotic substrates. This enzyme belongs to the GH13_44 subfamily and exhibits high hydrolytic activity toward ingested sugars, including sucrose and isomaltooligosaccharides. Structural comparisons based on the predicted model revealed that this enzyme possesses a more open substrate-binding pocket. As a result, it shows elevated activity toward substrates containing both α-1,4 and α-1,6 linkages, with a preference for α-1,6-linkages. These findings highlight the potential of this enzyme as a novel α-glucosidase with broad substrate specificity, enabling the utilization of prebiotic compounds in Ruminococcoides.

The online version contains supplementary material available at 10.1007/s10068-026-02109-9.