Postprandial glycemic attenuation of size-dependent α-glucan fractions via Gluconobacter oxydans biosynthesis

Slowly digestible carbohydrates have gained significant attention as functional ingredients for regulating blood glucose homeostasis, modulating appetite, and reducing the risk of obesity and type 2 diabetes. In this study, we explored a bioconversion strategy using Gluconobacter oxydans ATCC 11894 to synthesize polysaccharides with a high proportion of α-1,6 glycosidic linkages from maltodextrins. The bioconversion process effectively generates distinct polysaccharide fractions, including high-molecular-weight dextran, isomaltomegalosaccharides (IMSs), and low-molecular-weight byproducts, each with unique structural properties. IMSs, characterized by a complex network of α-1,4 and α-1,6 linkages, demonstrated significantly reduced susceptibility to mammalian α-glucosidase and slower enzymatic hydrolysis rates compared to dextran. Both in vitro and in vivo evaluations revealed that the polysaccharides modified through bioconversion, particularly the IMS-enriched fractions, effectively attenuated postprandial glucose spikes, prolonged glucose release, and sustained glucose availability. The unfractionated polysaccharides modified through bioconversion also showed promising potential for modulating glycemic responses, providing sustained energy release, and reducing the metabolic risks associated with hyperglycemia. Notably, this bioconversion process utilizes crude maltodextrins without requiring enzyme extraction or purified substrates, ensuring industrial scalability. These findings highlight the potential of G. oxydans-mediated bioconversion as a viable strategy for developing functional carbohydrate-based materials aimed at glycemic control and metabolic health.