Isolation and characterization of curdlan produced by Agrobacterium HX1126 using α-lactose as substrate

A strain Agrobacterium HX1126 was isolated from soil sample near the canal in Wuxi. α-lactose was used as the sole carbon source for the production of an exopolysaccharide which was named PLHX. The highest production of PLHX (21.4 g/L) was obtained under nitrogen depletion. PLHX composed mainly of glucose, with lower amounts of galactose and aminogalactose. The structure of the product was confirmed by NMR and FTIR and was identified as curdlan. This exopolysaccharide formed a gel when 30 g/L was put in boiling water for 10 min, with an achieved gel strength of 831 g/cm2. Moreover, a hypothesis for higher gel strength production is proposed. The gel forming property makes this exopolysaccaride a good potential application in the food, pharmaceutical and cosmetic industries.