EXOPOLYMERS FROM CURDLAN PRODUCTION - INCORPORATION OF GLUCOSE-RELATED SUGARS BY AGROBACTERIUM SP STRAIN ATCC 31749

Three different exopolymers were purified from cultures of Agrobacteri um sp. strain ATCC 31749 grown in a mineral salts medium containing 2% glucose at 30 degrees C for 5 days under aerobic culture conditions. These exopolymers were curdlan (extracellular, homo-beta-(1-3)-glucan, water insoluble at neutral pH), a water-soluble noncurdlan-type exopo lymer A (WSNCE-A), and a water-soluble noncurdlan-type exopolymer B (W SNCE-B). Curdlan, WSNCE-A, and WSNCE-B composed by weight 61, 27, and 12%, respectively, of the exopolymer produced from glucose. Compositio ns of all polymers were confirmed by gas chromatography (GC) and gas c hromatography - mass spectrometry (GC-MS). The WSNCE-A is composed of glucose and galactose with lower contents of rhamnose. The WSNCE-B con sists of glucose and mannose. To biosynthesize modified biopolymers, g lucose-related sugars including 3-O-methyl-D-glucose, 2-amino-2-deoxy- D-glucose, and 2-acetamido-2-deoxy-D-glucose (N-acetylglucosamine) wer e fed separately as the sole carbon source. Using 3-O-methyl-D-glucose , 8-12 mol% of the curdlan repeats were 3-O-methyl-D-glucose based on GC and H-1-nuclear magnetic resonance spectrometry. N-Acetylglucosamin e was incorporated into WSNCE-A at 10 mol% based on the CC-MS but was not found in curdlan or WSNCE-B.