@article{Nusrat_Rahman_2010, title={Partial Characterization of Extracellular α-Amylase from Three Bacillus Isolates}, volume={25}, url={https://www.banglajol.info/index.php/BJM/article/view/4864}, DOI={10.3329/bjm.v25i1.4864}, abstractNote={<p>α-Amylase produced by three <em>Bacillus </em>isolates had been compared on the basis of the following criteria: heat and pH effects on activity and stability, effect of metal ions on enzyme activity and kinetic parameters. The culture filtrates obtained by growing the organisms in starch medium were fractionated by ammonium sulphate precipitation technique, and the highest enzyme activities were recovered from 70% saturation fraction. The enzyme from <em>Bacillus amyloliquefaciens </em>showed optimum activity at 60°C, while <em>B. subtilis </em>and another <em>Bacillus </em>isolate at lower (55°C) temperature. The pH optima of the enzymes from all sources were between 6.5 and 7.0 with an optimum reaction time of 10 to 15 min. α-Amylases were moderately thermostable exhibiting almost full activities at 50°C for at least 20 min. The enzyme from all sources showed stability over a wide range of pH (4.0-8.5). The apparent K<sub>m</sub> values on soluble starch varied between 1.6 mg/ml in case of <em>B. amyloliquefaciens </em>and 2.5 mg/ml in case of <em>B. subtilis</em>. Metal ions like Mg<sup>2+</sup> and Mn<sup>2+</sup> seemed to have positive influence on the enzyme activities of <em>B. subtilis </em>and <em>Bacillus </em>sp. The enzyme activities from three isolates were strongly inhibited by Cu<sup>2+</sup>, Hg<sup>2+</sup> and Zn<sup>2+</sup>.</p> <p><strong>Key words:</strong> Extracellular α-amylase; <em>Bacillus </em>spp<em>.</em>; Enzyme characterization</p><p>DOI: <a href="http://dx.doi.org/10.3329/bjm.v25i1.4864">http://dx.doi.org/10.3329/bjm.v25i1.4864</a></p> <p><em>Bangladesh</em><em> J Microbiol</em>, Volume 25, Number 1, June 2008, pp 76-78</p>}, number={1}, journal={Bangladesh Journal of Microbiology}, author={Nusrat, Arifa and Rahman, Sabita Rezwana}, year={2010}, month={Apr.}, pages={76–78} }