Biodegradation of carboxymethyl celluloses by Agrobacterium CM-1

• Published in: Carbohydrate polymers 1995, Vol.27 (2), p.137-143
• Main Authors: Sieger, C.H.N., Kroon, A.G.M., Batelaan, J.G., van Ginkel, C.G.
• Format: Article
• Language: English
• Subjects: Agrobacterium; Applied sciences; beta-glucosidase; biodegradation; Biodegradation of pollutants; Biological and medical sciences; Biotechnology; carboxymethylcellulose; cellulases; Cellulose and derivatives; Environment and pollution; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; Industrial applications and implications. Economical aspects; Natural polymers; O-glycoside hydrolases; Physicochemistry of polymers
• ISSN: 0144-8617; 1879-1344
• DOI: 10.1016/0144-8617(95)00039-A

A Gram-negative rod tentatively identified as an Agrobacterium sp. was isolated from activated sludge with carboxymethyl cellulose (CMC) with a degree of substitution as the of 0.6 sole carbon and energy source. Not only did CMC DS (degree of substitution) 0·60 support the growth of this strain but also CMC DS 0.75, CMC DS 1·12, glucose and cellobiose. Agrobacterium CM-1 did not utilize cellulose. The metabolism of CMC is initiated by hydrolytic reactions catalysed by free and cell-bound endoglucanases. CMCs are only partially degraded by Agrobacterium CM-1. The extent of biodegradation of CMC DS 0.60, CMC DS 0.75 and CMC DS 1.12 determined in chemostat cultures increased with decreasing DS. The monomer compositions of CMCs and their biodegradation products revealed that only glucose and, remarkably, monosubstituted 6-glucose units are mineralized. As a consequence biodegradation of CMC by Agrobacterium CM-1 results in the formation of carboxymethylated oligomers with DS values greater than those of the original CMC. The DS of the original CMC also determined the chain length of the resulting oligomers.