Cold-active and NaCl-tolerant exo-inulinase from a cold-adapted Arthrobacter sp. MN8 and its potential for use in the production of fructose at low temperatures
| Autor: | Junjun Li, Minghe Mo, Zunxi Huang, Qian Lu, Rui Zhang, Bo Xu, Junmei Ding, Junpei Zhou, Xianghua Tang, Mozhen Peng |
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| Rok vydání: | 2014 |
| Předmět: |
Inulinase activity
Levanase Glycoside Hydrolases Acclimatization Inulin Molecular Sequence Data Bioengineering Bacillus Fructose Biology Sodium Chloride Applied Microbiology and Biotechnology chemistry.chemical_compound Arthrobacter Escherichia coli Food science Amino Acid Sequence Cloning Molecular Inulinase Hydrolysis biology.organism_classification Enzyme assay Cold Temperature chemistry Biochemistry biology.protein Biotechnology Jerusalem artichoke |
| Zdroj: | Journal of bioscience and bioengineering. 119(3) |
| ISSN: | 1347-4421 |
| Popis: | An exo-inulinase gene was cloned from Arthrobacter sp. MN8, a cold-adapted bacterium isolated from lead-zinc-rich soil. The gene was expressed in Escherichia coli BL21(DE3). The resultant 505-residue polypeptide (InuAMN8) showed the highest identity (81.1%) with the putative levanase from Arthrobacter phenanthrenivorans Sphe3 (ADX73279) and shared 57.8% identity with the exo-inulinase from Bacillus sp. snu-7 (AAK00768). The purified recombinant InuAMN8 (rInuAMN8) showed an apparently optimal activity at 35°C, and 75.3%, 39.4%, and 15.8% of its maximum activity at 20°C, 10°C, and 0°C, respectively. After pre-incubation for 60 min at 50°C and 55°C, the rInuAMN8 exhibited 69.8% and 17.7% of its initial activity, respectively. The apparent Km values of rInuAMN8 towards inulin were 2.8, 1.5, 1.2, 5.3, and 8.2 mM at 0°C, 10°C, 20°C, 30°C, and 35°C, respectively. Inulin and Jerusalem artichoke tubers were effectively hydrolyzed to release fructose by rInuAMN8 at 0°C, 10°C, and 35°C. Compared with its hyperthermophilic and thermophilic counterparts, the exo-inulinase had less aromatic amino acid F and more hydrophobic amino acid A. In addition, the purified rInuAMN8 retained 127.9%-88.4% inulinase activity at 3.5%-15.0% (w/v) NaCl concentrations. Zn(2+) and Pb(2+) at 10 mM exhibited little or no effect on the enzyme activity. This paper is the first to report a cold-active and/or NaCl-tolerant exo-inulinase from the genus Arthrobacter. The exo-inulinase rInuAMN8 shows a potential for use in the production of fructose at low temperatures. |
| Databáze: | OpenAIRE |
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