期刊
ENZYME AND MICROBIAL TECHNOLOGY
卷 39, 期 4, 页码 690-696出版社
ELSEVIER SCIENCE INC
DOI: 10.1016/j.enzmictec.2005.12.002
关键词
alpha-amylase; production; immobilization; alginate; capsules
Bacillus subtilis cells were immobilized by entrapment in calcium alginate gel capsules and the immobilized biocatalyst was used for the semi-continuous production of a-amylase. The alpha-amylase yield and operational stability of the immobilized system were increased by tailoring the capsules' characteristics. Capsules prepared from 2% (w/v) sodium alginate and 3.5% (w/v) CaCl2 were the best support for cell immobilization, providing 2.5-fold higher alpha-amylase production in comparison to the freely suspended cells. Immobilized biocatalysts sustained 90% of their initial productivity over five sequential batches in a 10-day period, while amylase production by free cells declined sharply after the second use. Even higher operational stability was achieved when the capsules were treated with 2% (w/v) CaCl2 for 30 min before each batch. In this case the appearance of free cells in the medium was minimized and the immobilized system retained more than 85% of its initial efficiency after 15 fermentation batches, producing more than 1,450,000 units of extracellular (c)-amylase during this period. (c) d 2005 Elsevier Inc. All rights reserved.
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