title: Cloning and Characterizing the Thermophilic and Detergent Stable Cellulase CelMytB from Saccharophagus sp. Myt-1.
abstract: We previously isolated and reported a second species of the Saccharophagus genus, Saccharophagus sp. strain Myt-1. In the present study, a cellulase gene (celMytB) from the genomic DNA of Myt-1 was cloned and characterized. The DNA sequence fragment contained an open reading frame of 1,893 bp that encoded a protein of 631 amino acids with an estimated molecular mass of 66.8 kDa. The deduced protein, CelMytB, had a catalytic domain that contained a conserved signature sequence (VIYEIYNEPL) of glycosyl hydrolase family 5 and a CBM6 cellulose binding module. CelMytB showed optimal activity at 55 °C and pH 6.5, which is similar to the optimal temperature and pH profile of cel5H, an endoglucanase from the closely related S. degradans 2-40. However, the cellulase (degradation of soluble cellulose) and avicelase (degradation of crystalline cellulose) activities of CelMytB were about 3-fold and 100-fold higher, respectively, than the equivalent activities of cel5H. Moreover, CelMytB could degrade xylan. From the zymogram results, we speculated that the catalytic domain of CelMytB had high activity even without the cellulose binding module. The presence of some detergents stimulated the cellulase activity of CelMytB.
authors.affiliation: Department of Environmental and Energy Science, Faculty of Earth and Environmental Systems, Graduate School of Science and Engineering, University of Toyama, Toyama, 930-8555 Japan.
authors.forename: Akihiro
authors.initials: A
authors.lastname: Sakatoku
authors.affiliation: Department of Environmental and Energy Science, Faculty of Earth and Environmental Systems, Graduate School of Science and Engineering, University of Toyama, Toyama, 930-8555 Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Tanaka
authors.affiliation: Department of Environmental and Energy Science, Faculty of Earth and Environmental Systems, Graduate School of Science and Engineering, University of Toyama, Toyama, 930-8555 Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kamachi
authors.affiliation: Department of Environmental and Energy Science, Faculty of Earth and Environmental Systems, Graduate School of Science and Engineering, University of Toyama, Toyama, 930-8555 Japan.
authors.forename: Shogo
authors.initials: S
authors.lastname: Nakamura
keywords: Cellulase; Detergent stable; Saccharophagus sp. Myt-1; Thermophilic; Xylanase