期刊
BIOSCIENCE BIOTECHNOLOGY AND BIOCHEMISTRY
卷 71, 期 10, 页码 2393-2401出版社
TAYLOR & FRANCIS LTD
DOI: 10.1271/bbb.60666
关键词
alkaline alpha-amylase; Bacillus halodurans; thermotolerance
A newly isolated strain, 38C-2-1, produced alkaline and thermotolerant alpha-amylases and was identified as Bacillus halodurans. The enzymes were purified to homogeneity and named alpha-amylase I and II. These showed molecular masses of 105 and 75 kDa respectively and showed maximal activities at 50-60 degrees C and pH 1011, and 42 and 38% relative activities at 30 degrees C. These results indicate that the enzymes are thermotolerant. The enzyme activity was not inhibited by a surfactant or a bleaching reagent used in detergents. A gene encoding a-amylase I was cloned and named amyI. Production of Amyl with a signal peptide repressed the growth of an Escherichia coli transformant. When enzyme production was induced by the addition of isopropyl beta-D(-)thiogalactopyranoside in the late exponential growth phase, the highest enzyme yield was observed. It was 45-fold that of the parent strain 38C-2-1.
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