title: Isolation and Characterization of a Glycosyl Hydrolase Family 16 β-Agarase from a Mangrove Soil Metagenomic Library.
abstract: A mangrove soil metagenomic library was constructed and a β-agarase gene designated as AgaML was isolated by functional screening. The gene encoded for a 659-amino-acids polypeptide with an estimated molecular mass of 71.6 kDa. The deduced polypeptide sequences of AgaML showed the highest identity of 73% with the glycoside hydrolase family 16 β-agarase from Microbulbifer agarilyticus in the GenBank database. AgaML was cloned and highly expressed in Escherichia coli BL21(DE3). The purified recombinant protein, AgaML, showed optimal activity at 50 °C and pH 7.0. The kinetic parameters of Km and Vmax values toward agarose were 4.6 mg·mL(-1) and 967.5 μM·min(-1)·mg(-1), respectively. AgaML hydrolyzed the β-1,4-glycosidic linkages of agar to generate neoagarotetraose (NA4) and neoagarohexaose (NA6) as the main products. These characteristics suggest that AgaML has potential application in cosmetic, pharmaceuticals and food industries.
authors.affiliation: Key Laboratory of Tropical Marine Bio-Resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China. maizhimao@scsio.ac.cn.
authors.forename: Zhimao
authors.initials: Z
authors.lastname: Mai
authors.affiliation: Key Laboratory of Tropical Marine Bio-Resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China. suhongfei17@126.com.
authors.forename: Hongfei
authors.initials: H
authors.lastname: Su
authors.affiliation: Key Laboratory of Tropical Marine Bio-Resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China. zhsimd@scsio.ac.cn.
authors.forename: Si
authors.initials: S
authors.lastname: Zhang
mesh_terms: D005697:Galactosides / Q000378:metabolism; D006026:Glycoside Hydrolases / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D056186:Metagenomics; D009844:Oligosaccharides / Q000378:metabolism; D012988:Soil Microbiology; D013696:Temperature
chemical_list: D005697:Galactosides; D009844:Oligosaccharides; C081798:neoagarotetraose; D006026:Glycoside Hydrolases; C019624:agarase
keywords: agar; agarase; metagenomic library; neoagaro-oligosaccharides