High-temperature, salt-tolerant xanthanase

A new high-temperature, salt-tolerant xanthanase suitable as an enzymic viscosity breaker for xanthanbased hydraulic fracture fluids was obtained by soil enrichment growth on xanthan gum incubated at 45°C in the presence of 3% NaCl. The mixed culture produces exoenzymes functional up to 65°C in the presence of salts. Degradation products include the pyruvic acetal of mannose and branched oligosaccharides derived from cleavage of main-chain β-(1→4)-d-glucosyl linkages. Release of the terminal pyruvic acetal ofd-mannose leads to oligosaccharide products that evidently contain the ene-4,5-unsaturated glucuronic acid residue.