Bacterial polysaccharides inhibit sucrose-induced hyperglycemia in silkworms.

Diabetes and obesity result from sucrose-induced hyperglycemia. Prevention of hyperglycemia contributes to inhibit the onset of these life-related diseases. Here we show that polysaccharides obtained from soil bacteria inhibit sucrose-induced hyperglycemia in an in vivo silkworm evaluation system. Ethanol precipitates of extracellular polysaccharides were prepared from viscous bacterial colonies. Among 24 samples obtained from different bacterial species, oral administration of 6 samples from Rhizobium altiplani, Cupriavidus sp., Paenibacillus polymyxa, Pantoea eucalypti, Variovorax boronicumulans, and Xanthomonas cynarae suppressed sucrose-induced hyperglycemia in silkworm insect larvae. The R. altiplani fraction treated further with DNase I, RNase A, and proteinase K, followed by phenol extraction also exhibited suppressive activity. Our results suggest that silkworms provide an efficient screening system of bacterial polysaccharides that inhibit sucrose-induced hyperglycemia.