Abstract

The synthesis of α-amylase AmyM3 from B. flexus 406 in the recombinant strain B. subtilis 168-28 was significantly repressed during submerged cultivation in nutrient medium supplemented with 1% glucose. Repression of α-amylase synthesis by glucose in B. subtilis cells is observed at the level of transcription and is mediated by the catabolite control protein CcpA. The effect of catabolite repression was eliminated after the deletion of a putative CRE site in the amyM3 gene, but the amount of extracellular α-amylase still significantly decreased in the presence of glucose. It was shown that, despite the high level of amyM3 gene activity, a shift in the cultivation medium pH to 5.8–6.0 due to glucose-overflow metabolites excreted by B. subtilis interferes with the synthesis of active extracellular α-amylase, which probably affects postsecretory folding of the enzyme. This observation is a newly demonstrated facet of the CcpA-mediated effect of preferentially utilized sugars on extracellular α-amylase production in Bacillus subtilis.

中文翻译：

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葡萄糖代谢产物对培养基的酸化抑制枯草芽孢杆菌 168 合成异源细胞外α-淀粉酶

摘要

α淀粉酶AmyM3的从合成B.弯曲芽孢406在重组菌株枯草芽孢杆菌168-28在补充有1％葡萄糖的营养培养基中浸没培养过程中显著抑制。在转录水平观察到枯草芽孢杆菌细胞中葡萄糖对 α-淀粉酶合成的抑制，并由分解代谢物控制蛋白 CcpA 介导。在amyM3基因中删除一个假定的 CRE 位点后，分解代谢物的抑制作用被消除，但在葡萄糖存在的情况下，细胞外 α-淀粉酶的数量仍然显着减少。结果表明，尽管amyM3水平很高基因活性，由于枯草芽孢杆菌分泌的葡萄糖溢出代谢物导致培养基 pH 值变化至 5.8-6.0 会干扰活性细胞外 α-淀粉酶的合成，这可能会影响酶的分泌后折叠。这一观察结果是 CcpA 介导的优先利用的糖对枯草芽孢杆菌细胞外 α-淀粉酶产生的影响的一个新方面。