Regulation of Amylase Synthesis in Bacillus circulans F-2

概要

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In the usual batch cultivation, Bacillus circulans F-2 produced amylase only when granular carbon sources such as raw starch or crosslinked starches (CLP) were added. In the dialysis cultivation, where CLP and partially purified amylase were incubated inside the dialysis tubing, the bacterium inoculated outside of the tubing grew and produced the amylase. Amylase production of this bacterium was further investigated in feeding cultivation, in which maltose was fed to the cultivation medium at various rates. The bacterial growth increased with the increase of the feeding rate of maltose, but maximum amylase production was observed at a feeding rate of 45 mg/hr/1. No amylase was produced on the media containing monosaccharides, sucrose, lactose, or isomaltose in the feeding cultivation although bacterial growth was observed. The amylase of this bacterium was found to be inducible. Replacement of 20% of the maltose with glucose resulted in a great decrease (70%) in the amylase production. This shows that the amylase synthesis of B. circulans F-2 is severely repressed by glucose.