title: Halophilic alkali- and thermostable amylase from a novel polyextremophilic Amphibacillus sp. NM-Ra2.
abstract: Extracellular gluco-amylo-pullulanase from Amphibacillus sp. NM-Ra2 was purified to homogeneity by ethanol precipitation, anion exchange chromatography and gel filtration chromatography. Molecular mass of the enzyme was 50kDa (SDS-PAGE). The enzyme showed maximal activity at 1.9 M NaCl, pH50°C 8.0 and 54°C and was active from 0 to 4.3 M NaCl and 37 to 65°C. The enzyme was inhibited by EDTA and was stable and active in the presence of PMSF, DTT, H2O2, Triton-X-100, Tween 20 and Tween 80. Ca2+ is inessential for activity. The amylase was stimulated with K+ and inhibited with Cu2+ and Mg2+. Hg2+, Zn2+ and Fe2+ had no effect on activity. Amylase was stable and active in the presence of ethanol, methanol and benzene (25%, v/v). The enzyme hydrolyzed linear and branched polysaccharides including pullulan, glycogen and amylopectin, and hydrolyzed raw wheat starch and raw corn starch (14.6% and 13.5% over 2 h). Amylase activity was inhibited by soluble starch concentrations greater than 0.3%. The major products of soluble starch hydrolysis were maltose and maltotriose. The amylase, being halophilic and alkali-thermostable, in addition to being resistant to surfactants, oxidizing agents and organic solvents, can find applications in the starch processing, pharmaceutical, food and paper/pulp industries.
authors.affiliation: Department of Biochemistry, Faculty of Pharmacy, Suez Canal University, Ismailia 41522, Egypt. Electronic address: noha_mesbah@pharm.suez.edu.eg.
authors.forename: Noha M
authors.initials: NM
authors.lastname: Mesbah
authors.affiliation: Department of Microbiology, University of Georgia, Athens, GA 30602, USA. Electronic address: juergenwiegel@gmail.com.
authors.forename: Juergen
authors.initials: J
authors.lastname: Wiegel
mesh_terms: D000468:Alkalies / Q000737:chemistry*; D000681:Amylases / Q000737:chemistry* / Q000302:isolation & purification; D001406:Bacillaceae / Q000737:chemistry*; D004789:Enzyme Activation; D004795:Enzyme Stability; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007477:Ions / Q000737:chemistry; D008670:Metals / Q000737:chemistry; D012965:Sodium Chloride / Q000494:pharmacology; D012997:Solvents; D013379:Substrate Specificity; D013696:Temperature
chemical_list: D000468:Alkalies; D007477:Ions; D008670:Metals; D012997:Solvents; D012965:Sodium Chloride; D000681:Amylases
keywords: Amylase; Halophilic alkalithermophilic; Wadi An Natrun