Characterization of salt-tolerant β-glucosidase with increased thermostability under high salinity conditions from Bacillus sp. SJ-10 isolated from jeotgal, a traditional Korean fermented seafood

Bioprocess Biosyst Eng. 2015 Jul;38(7):1335-46. doi: 10.1007/s00449-015-1375-x. Epub 2015 Feb 15.

Abstract

The β-glucosidase gene, bglC, was cloned from Bacillus sp. SJ-10 isolated from the squid jeotgal. Recombinant BglC protein overexpression was induced in Escherichia coli. The optimal pH and temperature of the enzyme, using p-nitrophenyl-β-D-glucopyranoside (pNPβGlc) as a substrate, were pH 6 and 40 °C, respectively. Enzymatic activity increased by 3.3- and 3.5-fold in the presence of 15% NaCl and KCl, respectively. Furthermore, enzyme thermostability improved in the presence of NaCl or KCl. At 45 °C in the presence of salts, the enzyme was stable for 2 h and maintained 80% activity. In the absence of salts, BglC completely lost activity after 110 min at 45 °C. Comparison of the kinetic parameters at various salt concentrations revealed that BglC had approximately 1.5- and 1.2-fold higher affinity and hydrolyzed pNPβGlc 1.9- and 2.1-fold faster in the presence of 15% NaCl and KCl, respectively. Additionally, the Gibb's free energy for denaturation was higher in the presence of 15% salt than in the absence of salt at 45 and 50 °C. Since enzymatic activity and thermostability were enhanced under high salinity conditions, BglC is an ideal salt-tolerant enzyme for further research and industrial applications.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacillus / metabolism*
  • Cloning, Molecular
  • Enzyme Stability
  • Fermentation*
  • Hot Temperature
  • Kinetics
  • Republic of Korea
  • Salinity*
  • Seafood*
  • Substrate Specificity
  • beta-Glucosidase / genetics
  • beta-Glucosidase / metabolism*

Substances

  • beta-Glucosidase