The enzyme Alpha-amylase accounts for about 30% of total enzyme production in the world and contributes to numerous industrial applications, extending from general products such as detergents, paper, beer and textiles to clinical biology, health science and even the pharmaceutical industry (cyclo-dextrin manufacture). This enzyme hydrolysis the internal a(1,4) glycosidic linkages present between glucose molecules within the polysaccharide starch, eventually degrading starch into glucose, maltose and dextrin. Alpha-amylases are metallo-enzymes and hence need calcium ions for stability, functioning and structural integrity. Alpha-amylase are mainly obtained from animals, plants and microbes (Chi et al. 2009; Maarel et al. 2002).
Microbial sources such as bacteria are most widely used to produce enzymes on a large scale. Among bacteria, the Bacillus species is selected for enzyme manufacture due to their high consistency and production capacity, lower production cost, faster production, non-pathogenic nature and increased purity and stability of the enzyme product.
[...] In contrast, Alpha-amylase from Bacillus stearothermophilus was found to maintain 60% activity, even after incubation at 100oC overnight. Additionally, according to Sivaramakrishnan et al. (2006), 40-50oC is regarded as optimal conditions for denatured Bacillus stearothermophilus Alpha-amylase to be reactivated. However, it is relatively difficult for denatured Bacillus subtilis Alpha-amylase to be reactivated. This implies that the protein structure of Bacillus subtilis Alpha-amylase is easily disrupted on exposure to high temperatures and cannot be restored to normal structure on cooling. These points further prove that Alpha-amylases produced from Bacillus stearothermophilus are very thermally stable and can hence, be applied in industries where temperature cannot be controlled easily or when high temperatures are required. [...]
[...] The comparison of thermo-stable Alpha-amylase products cloned in Bacillus stearothermophilus and Bacillus subtilis. Introduction The enzyme Alpha-amylase accounts for about 30% of total enzyme production in the world and contributes to numerous industrial applications, extending from general products such as detergents, paper, beer and textiles to clinical biology, health science and even the pharmaceutical industry (cyclo-dextrin manufacture). This enzyme hydrolyses the internal α(1,4) glycosidic linkages present between glucose molecules within the polysaccharide starch, eventually degrading starch into glucose, maltose and dextrin. [...]
[...] Widner, Thomas, Sternberg, Lammon, Behr, R & Sloma A 2000, ‘Development of marker free strains of Bacillus subtilis capable of secreting high levels of industrial enzymes', Journal of Industrial Microbiology and Biotechnology, vol pp. 204-212. Yang, CH, Huang, YC, Chen, CY, Wen, CY 2010, ‘Expression of Thermo bifidafusca thermostable raw starch-digesting alpha-amylase in Pichia pastoris and its application in raw sago starch hydrolysis', Journal of Industrial Microbiology and Biotechnology, vol pp. 401-406. [...]
[...] Comparison of the quality of Alpha-amylase product from Bacillus stearothermophilus and Bacillus subtilis Thermal stability Although temperature increases rate of reaction, high temperatures could affect enzymes by altering the shape of the active site due to breaking of bonds within the protein structure. Therefore, the higher the thermal stability of an enzyme the more favorable it is for industrial application. Sivaramakrishnan et al. (2006) noted that the stabilities of bacterial Alpha-amylase enzymes vary depending on what class of bacterial extremophile the amylase gene was derived from. [...]
[...] To further improve activity of the AN174 Alpha-amylase, enzyme purification was done using ammonium sulphate precipitation and DEAE column purification. Purification increased stability of the enzyme as during thermal stability testing 60% enzyme activity was retained at high temperature (80oC) treatment for an hour (Imanaka et al. 1982). Bacillus subtilis In a research by Ozcan and Altinalan (2001), the amyA gene was obtained from a strain of wild-type Bacillus subtilis RSKK246 and expressed in wild-type Bacillus subtilis strain YB886. The desired gene was extracted using the zymography technique which includes SDS-PAGE, and then purified. [...]
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