alpha -AMYLASE SYNTHESIS BY MUTANT OF BACILLUS SUBTILIS IMMOBILIZED ONTO CHANNEL ALUMINA BEADS

摘要

ABSTRACTS: A W sub(20)mutant strain derived from Bacillus subtilis H sub(1)using UV radiation and exposure to a mutagenic agent was used for alpha -amylase synthesis. Both cultures were characterized for growth and continuous alpha -amylase syntheses, and the isolated enzymes had the same molecular mass of similar to 55 kDa. W sub(20)cells, harvested from specific growth phase, were immobilized within alumina beads and placed in a bioreactor column; specific feedstock (FS) was used for alpha -amylase syntheses and was affected by its composition, and its flow rate as well as temperature. Maximal alpha -amylase productivity (427- mu M reducing sugar[s]-mL effluent-h) was achieved using stationary-phase cells and FS containing 3% starch kept at 45C and 100-mL-h flow rate. When FS, with 2% starch, was fed to the column at the same temperature but at a higher flow rate, productivities were reduced to 326 mu M. alpha -amylase synthesis by W sub(20)cells was affected by growth phase of cells used, column temperature and FS flow rate. Some immobilized cells were washed out from the column because of shear forces on bead surfaces by FS flow rate and by temperature. Scanning electron micrographs revealed large numbers of cells attached to external and internal bead channels. This article is a novel approach for alpha -amylase synthesis and can be used for its industrial production.