National Engineering Laboratory for High Efficient Enzyme Expression

Fuzhou, China

National Engineering Laboratory for High Efficient Enzyme Expression

Fuzhou, China
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Lian W.,Fuzhou University | Lin J.,Fuzhou University | Lin J.,National Engineering Laboratory for High Efficient Enzyme Expression | Wang G.,Fuzhou University | And 4 more authors.
Journal of Chinese Institute of Food Science and Technology | Year: 2017

A chitinase-producing strain B120 was isolated from Fujian soil and identified as Bacillus cereus by 16S rDNA sequence analysis. The chitinase-producing media were optimized and the optimal medium formulations were ob tained and as follow: lactose 3.5%, peptone 1.0%, powdered chitin 0.2%, K2HPO4 0.07%, KH2PO4 0.03%, MgSO4 0.05%, FeSO4-H20 0.002%, NaCl 0.5%, pH 6.0. Fermenting under these conditions for 84 h, chitinase activity could reach 603 U/L, 5.93 times higher than before optimization (87 U/L). Furthermore, the chitinase properties were studied. The results showed that the optimum reaction pH and temperature were 8.0 and 50℃, respectively. This enzyme was stable under 30℃ and pH 7.0-10.0, and more than 74% of relative activity was retained after incubation for 1 h. It was a kind of mesothermal and alkaline chitinases. © 2017, Editorial Office of Journal of CIFST. All right reserved.


Li R.-K.,Fuzhou University | Li R.-K.,National Engineering Laboratory for High Efficient Enzyme Expression | Chen P.,National Engineering Laboratory for High Efficient Enzyme Expression | Ng T.B.,Chinese University of Hong Kong | And 8 more authors.
Biotechnology and Applied Biochemistry | Year: 2015

A β-mannanase gene (Man5) from Bacillus subtilis BS5 was cloned by PCR and integrated into the genome of Pichia pastoris GS115 via pPIC9 vector. The recombinant Man5 with a molecular mass of 43 kDa was successfully expressed and secreted into the culture medium. After methanol induction in a shake flask for 96 H, the recombinant Man5 protein reached 375 μg/mL in concentration, with an enzyme activity of 892 U/mL. The recombinant Man5 was purified 3.35-fold with 60% yield by using HiTrap DEAE FF and HiTrap Phenyl FF columns. The specific activity of the purified enzyme was 7,978 U/mg. The optimum temperature and pH of the recombinant Man5 were 50 °C and 6.0, respectively. Studies of substrate specificity showed that the optimum substrate for the Man5 was konjac flour, suggesting that it has great potential as an effective additive in the food industry. © 2014 International Union of Biochemistry and Molecular Biology, Inc.

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