A thermostable alpha-amylase producing maltohexaose from a new isolated Bacillus sp US100: study of activity and molecular cloning of the corresponding gene

A Bacillus sp. US100 strain was isolated from Trunisian hot spring soil. Th is strain secretes a thermoactive amylase having an optimal temperature of 82 degrees C and a remarkable thermostability with a half time of 40 min at 110 degrees C in the presence of 20% (w/v) of substrate. The main end prod ucts of its action an starch are maltohexaose and maltopentaose which is th e smallest substrate hydrolyzed by this enzyme. The molecular cloning, in E . coli, of a 3-kb DNA fragment encoding far this activity is also reported (C) 1999 Elsevier Science Inc. All rights reserved.