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Production and purification of -amylase from halobacterium sodomense

Mohsen Mohamed Selim Asker, Osama Hamed El-Sayed, Magdy Ali Gadalaa, Sahera Fathalla Ali

The halophilic bacterial strain Halobacterium sodomense was shown to produce extracellular, halotolerant, alkali-stable and thermophilic -amylases activity. The culture conditions for higher amylases production were optimized with respect NaCl, temperature and substrates. Maximum amylase production was achieved in a mediumcontaining 25%NaCl at 55ºC in the presence of 1% soluble starch and Yeast extract. The enzyme was purified to homogeneitywith 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 homodimmer of 78 kDa polypeptide by SDS-PAGE. The optimum pH and temperature of the amylase were 6.0 and 55ºC, respectively. The purified enzymewas stable frompH 7.5 to 9.0 and able to prolong its thermal stability up to 70ºC. The amylase was activated by Na+, K+, Mn2+, Mg2+, and Fe2+. However, it was inhibited by Ca2+, Cd2+, Co2+, Zn2+, and EDTA. The purified amylase shows interesting properties useful for industrial applications.