title: A novel ∼34-kDa α-amylase from psychrotroph Exiguobacterium sp. SH3: production, purification, and characterization.
abstract: An amylase-producing psychrotroph bacterium was isolated from soil and identified as belonging to the genus Exiguobacterium. A novel cold-adapted α-amylase, Amy SH3, was purified from culture medium of this bacterium using acetone precipitation and DEAE-Sepharose anion-exchange chromatography. The molecular mass of the enzyme was estimated about 34 kDa using SDS-PAGE. Biochemical characterization of Amy SH3 revealed that the optimum temperature for maximum activity of Amy SH3 was 37°C. However, Amy SH3 was also active at cold temperatures, showing 13% and 39% activity at 0 and 10°C, respectively. The optimum pH for maximum activity of Amy SH3 was pH 7, whereas the amylase was active over a pH range of 5 to 10. The activity of Amy SH3 was enhanced by Co²⁺ but decreased by Mg²⁺, Mn²⁺, Zn²⁺, Fe²⁺, and Ca²⁺. Amy SH3 was able to retain 76% of its activity in the presence of 0.5% SDS. The K(m) and V(max) of the enzyme were calculated to be 0.06 mg/mL and 4,010 U/mL, respectively. The cold-adapted Amy SH3 seems very promising for applications at ambient temperature.
authors.affiliation: Department of Molecular Genetics, National Institute of Genetic Engineering and Biotechnology (NIGEB), Tehran, Iran.
authors.forename: Leila
authors.initials: L
authors.lastname: Mojallali
authors.forename: Hossein
authors.initials: H
authors.lastname: Shahbani Zahiri
authors.forename: Sarah
authors.initials: S
authors.lastname: Rajaei
authors.forename: Kambiz
authors.initials: K
authors.lastname: Akbari Noghabi
authors.forename: Kamahldin
authors.initials: K
authors.lastname: Haghbeen
mesh_terms: D056449:Bacillales / Q000201:enzymology*; D002852:Chromatography, Ion Exchange; D003470:Culture Media; D004591:Electrophoresis, Polyacrylamide Gel; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008970:Molecular Weight; D013696:Temperature; D000516:alpha-Amylases / Q000096:biosynthesis* / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification*
chemical_list: D003470:Culture Media; D000516:alpha-Amylases
keywords: Exiguobacterium; characterization; psychrotroph; purification; α-amylase