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Int. J. Mol. Sci. 2012, 13(8), 10505-10522; doi:10.3390/ijms130810505
Article

A Novel Cyclodextrin Glycosyltransferase from Alkaliphilic Amphibacillus sp. NPST-10: Purification and Properties

1,* , 1
,
1
,
1
 and
2
1 Department of Botany and Microbiology, College of Science, King Saud University, Riyadh 11451, Kingdom of Saudi Arabia 2 Institute of Technical Microbiology, Hamburg University of Technology, Kasernenstrasse 12, 21073 Hamburg, Germany
* Author to whom correspondence should be addressed.
Received: 26 June 2012 / Revised: 5 August 2012 / Accepted: 10 August 2012 / Published: 22 August 2012
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Abstract

Screening for cyclodextrin glycosyltransferase (CGTase)-producing alkaliphilic bacteria from samples collected from hyper saline soda lakes (Wadi Natrun Valley, Egypt), resulted in isolation of potent CGTase producing alkaliphilic bacterium, termed NPST-10. 16S rDNA sequence analysis identified the isolate as Amphibacillus sp. CGTase was purified to homogeneity up to 22.1 fold by starch adsorption and anion exchange chromatography with a yield of 44.7%. The purified enzyme was a monomeric protein with an estimated molecular weight of 92 kDa using SDS-PAGE. Catalytic activities of the enzyme were found to be 88.8 U mg−1 protein, 20.0 U mg−1 protein and 11.0 U mg−1 protein for cyclization, coupling and hydrolytic activities, respectively. The enzyme was stable over a wide pH range from pH 5.0 to 11.0, with a maximal activity at pH 8.0. CGTase exhibited activity over a wide temperature range from 45 °C to 70 °C, with maximal activity at 50 °C and was stable at 30 °C to 55 °C for at least 1 h. Thermal stability of the purified enzyme could be significantly improved in the presence of CaCl2. Km and Vmax values were estimated using soluble starch as a substrate to be 1.7 ± 0.15 mg/mL and 100 ± 2.0 μmol/min, respectively. CGTase was significantly inhibited in the presence of Co2+, Zn2+, Cu2+, Hg2+, Ba2+, Cd2+, and 2-mercaptoethanol. To the best of our knowledge, this is the first report of CGTase production by Amphibacillus sp. The achieved high conversion of insoluble raw corn starch into cyclodextrins (67.2%) with production of mainly β-CD (86.4%), makes Amphibacillus sp. NPST-10 desirable for the cyclodextrin production industry.
Keywords: alkaliphiles; soda lakes; cyclodextrin glycosyltransferase; Amphibacillus sp.; purification; 16S rDNA alkaliphiles; soda lakes; cyclodextrin glycosyltransferase; Amphibacillus sp.; purification; 16S rDNA
This is an open access article distributed under the Creative Commons Attribution License (CC BY 3.0).

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Ibrahim, A.S.S.; Al-Salamah, A.A.; El-Tayeb, M.A.; El-Badawi, Y.B.; Antranikian, G. A Novel Cyclodextrin Glycosyltransferase from Alkaliphilic Amphibacillus sp. NPST-10: Purification and Properties. Int. J. Mol. Sci. 2012, 13, 10505-10522.

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