Purifikasi dan Karakterisasi α-amilase Termostabil dari Bacillus stearothermophilus TII-12

Abstract

<p>Purification and Characterization of Thermostable<br />α-amylase from Bacillus stearothermophilus TII-12. Puji<br />Lestari, Nur Richana, Abdul A. Darwis, Khaswar Syamsu,<br />and Untung Murdiyatmo. Thermostable α-amylase is a<br />potential enzyme employed in the starch processing and<br />widely used in food industries, but this enzyme is still<br />imported. The local enzyme production would be more<br />economist and useful for its broad applications. Here we<br />report α-amylase from indigenous bacteria TII-12 which was<br />purified and characterized, as well as analyzed its hydrolysis<br />product on cassava starch. The enzyme of Bacillus<br />stearothermophilus TII-12 partially purified by ultrafiltration,<br />acetone precipitation and gel filtration (Sephadex G-100)<br />showed the reduced total activity, total protein and yield, but<br />increased the specific activity. The enzyme had a Km of 1,06<br />mg/ml and Vmax of 1,21 mol/min, with optimal activity at pH 7<br />and 90oC. An apparent molecular mass was of 192.932,8<br />Dalton, as estimated by Native-Polyacrylamide Agarose Gel<br />electrophoresis. Its activity was inhibited by the divalent<br />cation chelator such as EDTA and CuSO4 but activated by<br />calcium ion. Hydrolysis products of this enzyme on cassava<br />starch were glucose, dextrin, maltose and oligosaccharides.<br />After 24 hours of hydrolysis, the concentration of glucose<br />and maltose reached 51.970 and 10.090 ppm, respectively.<br />The thermostable α-amylase of TII-12 is an endo-α-amylase<br />and prospective to be applied on starch liquefaction with<br />high temperature process.</p>