文献类型：期刊文献

英文题名：Characterization of a thermostable raw-starch hydrolyzing α-amylase from deep-sea thermophile Geobacillus sp.

作者：Jiang, Tao[1];Cai, Menghao[1];Huang, Mengmeng[1];He, Hao[1];Lu, Jian[1];Zhou, Xiangshan[1];Zhang, Yuanxing[1,2]

机构：[1]E China Univ Sci & Technol, State Key Lab Bioreactor Engn, Shanghai 200237, Peoples R China;[2]Shanghai Collaborat Innovat Ctr Biomfg Technol, Shanghai 200237, Peoples R China

年份：2015

卷号：114

起止页码：15

外文期刊名：PROTEIN EXPRESSION AND PURIFICATION

收录：;WOS:【SCI-EXPANDED(收录号:WOS:000362463500003)】；

基金：This work was financially supported by the Chinese National High Technology Research and Development Program (Nos. 2012AA092103, 2012AA092105). We thank Prof. Runying Zeng, Third Institute of Oceanography of China for supply of the strain and other help.

语种：英文

外文关键词：alpha-Amylase; Geobacillus sp.; Heterologous expression; Thermophile

摘要：A deep-sea thermophile, Geobacillus sp. 4j, was identified to grow on starch and produce thermostable amylase. N-terminally truncated form of Geobacillus sp. 4j alpha-amylase (Gs4j-amyA) was fused at its N-terminal end with the signal peptide of outer membrane protein A (OmpA) of Escherichia coli. The enzyme was over-expressed in E. coli BL21 with a maximum extracellular production of 130 U/ml in shake flask. The yield of the transformant increased 22-fold as compared with that of the wild strain. The recombinant enzyme purified to apparent homogeneity by metal-affinity chromatography, exhibited a molecular mass of 62 kDa. It displayed the maximal activity at 60-65 degrees C and pH 5.5. Its half-life (t(1/2)) at 80 degrees C was 4.25 h with a temperature deactivation energy of 166.3 kJ/mol. Compared to three commonly used commercial alpha-amylases, the Gs4j-amyA exhibited similar thermostable performance to BLA but better than BAA and BSA. It also showed a universally efficient raw starch hydrolysis performance superior to commercial alpha-amylases at an acidic pH approaching nature of starch slurry. As a new acidic-resistant thermostable alpha-amylase, it has the potential to bypass the industrial gelatinization step in raw starch hydrolysis. (C) 2015 Elsevier Inc. All rights reserved.