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Electronic Journal of Biotechnology
Universidad Católica de Valparaíso
ISSN: 0717-3458
Vol. 18, No. 2, 2015, pp. 103-109
Bioline Code: ej15018
Full paper language: English
Document type: Research Article
Document available free of charge

Electronic Journal of Biotechnology, Vol. 18, No. 2, 2015, pp. 103-109

 en Cloning, expression and characterization of the endoglucanase gene from Bacillus subtilis check for this species in other resources UMC7 isolated from the gut of the indigenous termite Macrotermes malaccensis in Escherichia coli check for this species in other resources
Wei, Kelvin Swee Chuan; Teoh, Teow Chong; Koshy, Philip; Salmah, Ismail & Zainudin, Arifin

Abstract

Background: Bacillus subtilis check for this species in other resources UMC7 isolated from the gut of termite Macrotermes malaccensis has the ability to secrete a significant amount of extracellular endoglucanase, with an enzyme activity of 0.12 ± 0.01 μmol/min/ mL. However, for economically viable industrial applications, the enzyme needs to be expressed in a heterologous host to overcome the low enzyme production from the wild-type strain.
Results: The endoglucanase gene from B. subtilis UMC7 was successfully cloned and expressed. A higher enzyme activity was observed in the intracellular fraction of the recombinant clone (0.51 ± 0.02 μmol/ min/mL) compared with the cell-bound fraction (0.37 ± 0.02 μmol/min/mL) and the extracellular fraction (0.33 ± 0.01 μmol/min/mL). The recombinant endoglucanase was approximately 56 kDa, with optimal enzyme activity at 60°C and pH 6.0. The activity of the enzyme was enhanced by the addition of Ca2+. However, the enzyme was inhibited by other metal ions in the following order: Fe3+ > Ni2+ > Cu2+ > Mn2+ = Zn2+ > Mg2+ > Cd2+ > Cr2+. The enzyme was able to hydrolyze both low- and high-viscosity carboxymethyl-cellulose (CMC), avicel, cotton linter, filter paper and avicel but not starch, xylan, chitin, pectin and p-nitrophenyl α-D-glucopyranoside.
Conclusions: The recombinant endoglucanase showed a threefold increase in extracellular enzyme activity compared with the wild-type strain. This result revealed the potential of endoglucanase expression in E. coli, which can be induced for the overexpression of the enzyme. The enzyme has a broad range of activity with high specificity toward cellulose.

Keywords
β-1,4-Endoglucanase; Carboxyl-methylcellulose; Extracellular enzyme activity; Metal ions effect

 
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