Selective preparation of N-acetyl-D-glucosamine and N,N′-diacetylchitobiose from chitin using a crude enzyme preparation from Aeromonas sp.

A bacterium, Aeromonas sp. GJ-18, having strong chitinolytic activity was isolated from coastal soil and used for crude enzyme preparations. This enzyme preparation contained N-acetyl-D-glucosaminidase and N,N′-diacetylchitobiohydrolase. N-Acetyl-D-glucosaminidase was inactive above 50 °C, but N,N′-diacetylchitobiohydrolase was stable at this temperature. Utilizing the temperature sensitivities of the chitin degradation enzymes in crude enzyme preparation, N-acetyl-D-glucosamine (GlcNAc) and N,N′-diacetylchitobiose [(GlcNAc)2] were selectively produced from chitin. At 45 °C, GlcNAc was produced as a major hydrolytic product (94% composition) with a yield of 74% in 5 d, meanwhile at 55 °C (GlcNAc)2 was the major product (86%) with a yield of 35% within 5 d.