Glycoside hydrolase family 9 processive endoglucanase from Clostridium phytofermentans: Heterologous expression, characterization, and synergy with family 48 cellobiohydrolase

• Published in: Bioresource technology 2010-07, Vol.101 (14), p.5534-5538
• Main Authors: Zhang, Xiao-Zhou, Sathitsuksanoh, Noppadon, Zhang, Y.-H.P.
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Cellobiose - chemistry; Cellulase; Cellulose - analogs & derivatives; Cellulose - chemistry; Clostridium; Clostridium - metabolism; Clostridium phytofermentans; Escherichia coli; Escherichia coli - metabolism; Family 9 glycoside hydrolase; Filtration; Fundamental and applied biological sciences. Psychology; Glucose - chemistry; Glycoside Hydrolases - chemistry; Hydrogen-Ion Concentration; Hydrolysis; Industrial Microbiology - methods; Plasmids - metabolism; Processive endoglucanase; Synergy; Temperature; Tetroses - chemistry; Trioses - chemistry
• ISSN: 0960-8524; 1873-2976
• DOI: 10.1016/j.biortech.2010.01.152

The glycoside hydrolase family 9 cellulase (Cel9) from Clostridium phytofermentans has a multi-modular structure and is essential for cellulose hydrolysis. In order to facilitate production and purification of Cel9, recombinant Cel9 was functionally expressed in Escherichia coli. Cel9 exhibited maximum activity at pH 6.5 and 65 °C on carboxymethyl cellulose in a 10-min reaction period. The hydrolysis products on regenerated amorphous cellulose (RAC) were cellotetraose (a major product), cellotriose, cellobiose and glucose, and 71–80% of the reducing sugars produced by Cel9 were in soluble form, suggesting that Cel9 was a processive endoglucanase. The highest synergy between C. phytofermentans Cel9 and C. phytofermentans cellobiohydrolase Cel48 on Avicel was about 1.8 at a ratio of about 1:5. Cel9 alone was sufficient to solublize filter paper while Cel48 was not; however, it enhanced the solublization process along with Cel9 synergistically. This study provided useful information for understanding of the cellulose hydrolysis mechanism of this cellulolytic bacterium with potential industrial importance.