The chemical and digestive properties of a soluble glucan from Agrobacterium sp. ZX09

A salt-tolerant strain Agrobacterium sp. ZX09 produced a high molecular mass, water-soluble extracellular polysaccharide (EPS) composed of d-glucose. By examining periodate oxidation, 1H NMR and 13C NMR spectra, it was proven that the EPS consisted of the following repeating unit: →3)-β-d-Glcp-(1 → 3)-[β-d-Glcp-(1 → 3)-β-d-Glcp-(1 → 3)]3-α-d-Glcp-(1 → 3)-α-d-Glcp-(1→. In vitro the EPS was indigestible by α-amylase, and strongly inhibited pancreatic α-amylase activity. Fasting mice fed on the EPS failed to increase blood glucose levels. Experimental diets containing the EPS suppressed steep increase in blood glucose concentration. These results suggest that the novel water-soluble glucan could be potentially useful for decreasing absorption of dietary carbohydrate and postprandial blood glucose level.