title: Characterization of an exo-inulinase from Arthrobacter: a novel NaCl-tolerant exo-inulinase with high molecular mass.
abstract: A glycoside hydrolase family 32 exo-inulinase gene was cloned from Arthrobacter sp. HJ7 isolated from saline soil located in Heijing town. The gene encodes an 892-residue polypeptide with a calculated mass of 95.1 kDa and a high total frequency of amino acid residues G, A, and V (30.0%). Escherichia coli BL21 (DE3) cells were used as hosts to express the exo-inulinase gene. The recombinant exo-inulinase (rInuAHJ7) showed an apparently maximal activity at pH 5.0-5.5 and 40-45°C. The addition of 1.0 and 10.0 mM Zn(2+) and Pb(2+) had little or no effect on the enzyme activity. rInuAHJ7 exhibited good salt tolerance, retaining more than 98% inulinase activity at a concentration of 3.0%-20.0% (w/v) NaCl. Fructose was the main product of inulin, levan, and Jerusalem artichoke tubers hydrolyzed by the enzyme. The present study is the first to report the identification and characterization of an Arthrobacter sp exo-inulinase showing a high molecular mass of 95.1 kDa and NaCl tolerance. These results suggest that the exo-inulinase might be an alternative material for potential applications in processing seafood and other foods with high saline contents, such as marine algae, pickles, and sauces.
authors.affiliation: a Engineering Research Center of Sustainable Development and Utilization of Biomass Energy; Ministry of Education ; Yunnan Normal University ; Kunming , PR China.
authors.forename: Jidong
authors.initials: J
authors.lastname: Shen
authors.forename: Rui
authors.initials: R
authors.lastname: Zhang
authors.forename: Junjun
authors.initials: J
authors.lastname: Li
authors.forename: Xianghua
authors.initials: X
authors.lastname: Tang
authors.forename: Ruixian
authors.initials: R
authors.lastname: Li
authors.forename: Min
authors.initials: M
authors.lastname: Wang
authors.forename: Zunxi
authors.initials: Z
authors.lastname: Huang
authors.forename: Junpei
authors.initials: J
authors.lastname: Zhou
mesh_terms: D001173:Arthrobacter / Q000201:enzymology*; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D006026:Glycoside Hydrolases / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D007854:Lead / Q000494:pharmacology; D011994:Recombinant Proteins / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D055049:Salt Tolerance / Q000235:genetics; D012965:Sodium Chloride / Q000494:pharmacology; D015032:Zinc / Q000494:pharmacology
chemical_list: D011994:Recombinant Proteins; D007854:Lead; D012965:Sodium Chloride; D006026:Glycoside Hydrolases; C023086:inulinase; D015032:Zinc
keywords: Arthrobacter; NaCl; exo-inulinase; lead; zinc