title: Purification and characterization of an extracellular alpha-amylase from Bacillus subtilis AX20.
abstract: A Bacillus subtilis AX20 from soil with ability to produce extracellular alpha-amylases was isolated. The characterization of microorganism was performed by biochemical tests as well as 16S rDNA sequencing. Maximum amylase activity (38 U/ml) was obtained at stationery phase when the culture was grown at 37 degrees C. The enzyme was purified to homogeneity with an overall recovery of 24.2% and specific activity of 4133 U/mg. The native protein showed a molecular mass of 149 kDa composed of a homodimer of 78 kDa polypeptide by SDS-PAGE. The optimum pH and temperature of the amylase were 6 and 55 degrees C, respectively. The enzyme was inhibited by Hg(2+), Ag(2+), and Cu(2+) and it did not show an obligate requirement of metal ions. The enzyme was not inhibited by EDTA or EGTA, suggesting that this enzyme is not a metalloenzyme. The end products of corn starch and soluble starch were glucose (70-75%) and maltose (20-25%). Rapid reduction of blue value and the end products suggest an endo mode of action for the amylase. The purified amylase shows interesting properties useful for industrial applications.
authors.affiliation: Razi Vaccine and Serum Institute, Ahmadabad Street, Mashad, Iran. najafi99@yahoo.com
authors.forename: Mohsen Fathi
authors.initials: MF
authors.lastname: Najafi
authors.forename: Dileep
authors.initials: D
authors.lastname: Deobagkar
authors.forename: Deepti
authors.initials: D
authors.lastname: Deobagkar
mesh_terms: D001412:Bacillus subtilis / Q000201:enzymology*; D001426:Bacterial Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000302:isolation & purification*; D004795:Enzyme Stability; D005947:Glucose / Q000096:biosynthesis; D006863:Hydrogen-Ion Concentration; D008320:Maltose / Q000096:biosynthesis; D019216:Metals, Heavy / Q000494:pharmacology; D013329:Structure-Activity Relationship; D013696:Temperature; D000516:alpha-Amylases / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000302:isolation & purification*
chemical_list: D001426:Bacterial Proteins; D019216:Metals, Heavy; D008320:Maltose; D000516:alpha-Amylases; D005947:Glucose