title: A novel cyclodextrin glycosyltransferase from Alkaliphilic Amphibacillus sp. NPST-10: purification and properties.
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 CaCl(2). K(m) and V(max) 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 Co(2+), Zn(2+), Cu(2+), Hg(2+), Ba(2+), Cd(2+), 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.
authors.affiliation: Department of Botany and Microbiology, College of Science, King Saud University, Riyadh 11451, Kingdom of Saudi Arabia.
authors.forename: Abdelnasser S S
authors.initials: ASS
authors.lastname: Ibrahim
authors.affiliation: Department of Botany and Microbiology, College of Science, King Saud University, Riyadh 11451, Kingdom of Saudi Arabia.
authors.forename: Ali A
authors.initials: AA
authors.lastname: Al-Salamah
authors.affiliation: Department of Botany and Microbiology, College of Science, King Saud University, Riyadh 11451, Kingdom of Saudi Arabia.
authors.forename: Mohamed A
authors.initials: MA
authors.lastname: El-Tayeb
authors.affiliation: Department of Botany and Microbiology, College of Science, King Saud University, Riyadh 11451, Kingdom of Saudi Arabia.
authors.forename: Yahya B
authors.initials: YB
authors.lastname: El-Badawi
authors.affiliation: Institute of Technical Microbiology, Hamburg University of Technology, Kasernenstrasse 12, 21073 Hamburg, Germany.
authors.forename: Garabed
authors.initials: G
authors.lastname: Antranikian
mesh_terms: D001406:Bacillaceae / Q000201:enzymology*; D003505:Cyclodextrins / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D004795:Enzyme Stability; D019015:Geologic Sediments / Q000737:chemistry; D005964:Glucosyltransferases / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007700:Kinetics; D008958:Models, Molecular; D015394:Molecular Structure; D008970:Molecular Weight; D013379:Substrate Specificity; D013696:Temperature; D014867:Water / Q000737:chemistry
chemical_list: D003505:Cyclodextrins; D014867:Water; D005964:Glucosyltransferases; C019963:cyclomaltodextrin glucanotransferase