title: Purification and characterization of a salt-tolerant cellulase from the mangrove oyster, Crassostrea rivularis.
abstract: A cellulase with wide range of pH resistance and high salt tolerance was isolated from the digestive gland of the oyster Crassostrea rivularis living in mangrove forests. The 27 kDa cellulase named as CrCel was purified 40.6 folds by anion exchange chromatography and extraction from the gel after non-reducing sodium dodecylsufate-polyacrylamide gel electrophoresis. The specific activity of the purified cellulase was 23.4 U/mg against carboxymethyl cellulose (CMC). The N-terminal amino acid sequence of CrCel was determined to be NQKCQANSRV. CrCel preferably hydrolyzes β-1,4-glucosidic bonds in the amorphous parts of cellulose materials and displays degradation activity toward xylan. The Km and Vmax values of CrCel for CMC were determined to be 2.1% ± 0.4% and 73.5 ± 3.3 U mg(-1), respectively. The optimal pH value and temperature of CrCel were 5.5 and 40°C, respectively. The enzyme was stable in a wide range of pH, retaining over 60% activity after incubation for 80 min in the pH range of 3.0-9.0. In addition, CrCel showed remarkable tolerance to salt and remained active at high NaCl concentrations, but also retained over 70% activity after incubation in 0.5-2 M NaCl for up to 24 h. On the basis of the N-terminal sequence alignment and its similar properties to other animal cellulases, CrCel was regarded as a member of glycosyl hydrolase family 45 β-1,4-glucanases. CrCel is the first reported cellulase isolated from mangrove invertebrates, which suggests that it may participate in the assimilation of cellulolytic materials derived from the food sources of the oyster and contribute to the consumption of mangrove primary production. The unique properties of this enzyme make it a potential candidate for further industrial application.
authors.affiliation: Key Laboratory of Tropic Biological Resources, Minister of Education, College of Marine Science, Hainan University, Haikou 570228, China.
authors.forename: Tianchen
authors.initials: T
authors.lastname: An
authors.affiliation: Key Laboratory of Tropic Biological Resources, Minister of Education, College of Marine Science, Hainan University, Haikou 570228, China.
authors.forename: Zhu
authors.initials: Z
authors.lastname: Dong
authors.affiliation: Key Laboratory of Tropic Biological Resources, Minister of Education, College of Marine Science, Hainan University, Haikou 570228, China.
authors.forename: Junchen
authors.initials: J
authors.lastname: Lv
authors.affiliation: School of Life Science, Jilin Normal University, Siping 136000, China.
authors.forename: Yujun
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Hainan Key Laboratory of Tropical Animal Reproduction & Breeding and Epidemic Disease Research, Hainan University, Haikou 570228, China.
authors.forename: Manchuriga
authors.initials: M
authors.lastname: Wang
authors.affiliation: Hainan Key Laboratory of Tropical Animal Reproduction & Breeding and Epidemic Disease Research, Hainan University, Haikou 570228, China.
authors.forename: Shuangshuang
authors.initials: S
authors.lastname: Wei
authors.affiliation: Key Laboratory of Tropic Biological Resources, Minister of Education, College of Marine Science, Hainan University, Haikou 570228, China.
authors.forename: Yanting
authors.initials: Y
authors.lastname: Song
authors.affiliation: Key Laboratory of Tropic Biological Resources, Minister of Education, College of Marine Science, Hainan University, Haikou 570228, China yingxiazhang@hotmail.com dsm701@126.com.
authors.forename: Yingxia
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Tropic Biological Resources, Minister of Education, College of Marine Science, Hainan University, Haikou 570228, China yingxiazhang@hotmail.com dsm701@126.com.
authors.forename: Shiming
authors.initials: S
authors.lastname: Deng
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D055162:Biocatalysis / Q000187:drug effects; D002266:Carboxymethylcellulose Sodium / Q000378:metabolism*; D002480:Cellulase / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D002482:Cellulose / Q000378:metabolism*; D049896:Crassostrea / Q000201:enzymology*; D004492:Edetic Acid / Q000494:pharmacology; D004591:Electrophoresis, Polyacrylamide Gel; D004795:Enzyme Stability; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D011189:Potassium Chloride / Q000494:pharmacology; D020539:Sequence Analysis, Protein; D017386:Sequence Homology, Amino Acid; D012965:Sodium Chloride / Q000494:pharmacology; D013379:Substrate Specificity; D013696:Temperature
chemical_list: D012965:Sodium Chloride; D011189:Potassium Chloride; D002482:Cellulose; D004492:Edetic Acid; D002480:Cellulase; D002266:Carboxymethylcellulose Sodium
keywords: Crassostrea rivularis; cellulase; endo-β-1,4-glucanase; mangrove; oyster