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Purification and Characterization of Thermostable α‐Amylase from a Newly Isolated Thermophilic Bacillus stearothermophilus GRE 1
Author(s) -
Zakir Hossain S.M.,
Haki G.D.,
Rakshit S.K.
Publication year - 2005
Publication title -
developments in chemical engineering and mineral processing
Language(s) - English
Resource type - Journals
eISSN - 1932-2143
pISSN - 0969-1855
DOI - 10.1002/apj.5500130502
Subject(s) - thermophile , enzyme , chromatography , amylase , size exclusion chromatography , chemistry , incubation , enzyme assay , bacillus (shape) , specific activity , bioreactor , biochemistry , biology , microbiology and biotechnology , organic chemistry
A thermophilic bacterium, Bacillus stearothermophilus GRE 1, isolated from an Ethiopian hyperthermal spring produced a thermostable α‐amylase. Enzyme production in shake flask experiments while using optimum nutrient supplements and environmental conditions was 2.35 U/ml. Under optimized conditions in a bioreactor, 5‐6 fold higher enzyme activity was obtained than that of a shake flask. Gel filtration chromatography yielded a purification factor of 33.62‐fold and a recovery of 46.52%. The optimum temperature for activity was determined to be 60‐70d̀C and optimum pH was in the range of 5.5‐6.0. The enzyme maintained 50% of its original activity after 45 minutes of incubation at 80d̀C, and is stable at pH values of 5.0‐9.0. Enzyme activity was strongly inhibited by Cu 2+ , Zn 2+ and Fe 2+ . The enzyme is calcium independent and 94% and 86% relative activities were displayed with low concentrations of Co 2+ and Mg 2+ , respectively.