Pullulanase is a debranching enzyme commonly used in the starch processing industry. Production of a thermostable pullulanase with high activity is desired due to the application of the enzyme to starch processing at high temperature. In this study, a thermostable pullulanase with high activity is overproduced in Bacillus subtilis. Via improvement of the plasmid backbones, promoters, and ribosome‐binding‐site (RBS) sequences, an optimal recombinant strain B. subtilis WB800/RBS7 is obtained with an extracellular pullulanase activity of 154.9 U mL⁻¹ in a shake flask, which is 136.8 times higher than that of the wild type. When the strain is cultured in a 5‐L bioreactor, the pullulanase activity is significantly improved to 269.1 U mL⁻¹ (2.74 mg mL⁻¹). These results are expected to aid pullulanase production in industrial starch debranching applications.

中文翻译：

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通过优化表达元件在枯草芽孢杆菌中产生热稳定的支链淀粉酶

支链淀粉酶是淀粉加工工业中常用的脱支酶。由于将酶应用于高温下的淀粉加工，因此期望生产具有高活性的热稳定的支链淀粉酶。在这项研究中，枯草芽孢杆菌中过量生产了具有高活性的热稳定支链淀粉酶。通过改进质粒主链，启动子和核糖体结合位点（RBS）序列，在摇瓶中获得了最佳重组菌株枯草芽孢杆菌WB800 / RBS7，其胞外支链淀粉酶活性为154.9 U mL ^-1。是野生型的136.8倍。在5L生物反应器中培养菌株时，支链淀粉酶活性显着提高至269.1 U mL ^-1（2.74 mg mL ^-1）。预期这些结果将有助于工业淀粉脱支应用中的支链淀粉酶的生产。