title: 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.
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.
authors: Department of Biotechnology, Pukyong National University, Busan, 608-737, Korea.
authors: Jong Min
authors: JM
authors: Lee
authors: Yu-Ri
authors: YR
authors: Kim
authors: Joong Kyun
authors: JK
authors: Kim
authors: Gwi-Taek
authors: GT
authors: Jeong
authors: Jeong-Chul
authors: JC
authors: Ha
authors: In-Soo
authors: IS
authors: Kong
mesh_terms: D001407:Bacillus / Q000378:metabolism*; D003001:Cloning, Molecular; D004795:Enzyme Stability; D005285:Fermentation; D006358:Hot Temperature; D007700:Kinetics; D056910:Republic of Korea; D054712:Salinity; D017747:Seafood; D013379:Substrate Specificity; D001617:beta-Glucosidase / Q000235:genetics / Q000378:metabolism*
chemical_list: D001617:beta-Glucosidase