Cell surface engineering was proven as the efficient strategy for enhanced production of target metabolites. In this study, we want to improve the yield of target protein by engineering cell surface in Bacillus licheniformis. First, our results confirmed that deletions of D-alanyl-lipoteichoic acid synthetase gene dltD, cardiolipin synthase gene clsA and CDP-diacylglycerol-serine O-phosphatidyltransferase gene pssA were not conducive to cell growth, and the biomass of gene deletion strains were, respectively, decreased by 10.54 ± 1.43%, 14.17 ± 1.51%, and 17.55 ± 1.28%, while the concentrations of total extracellular proteins were improved, due to the increases of cell surface net negative charge and cell membrane permeability. In addition, the activities of target proteins, nattokinase, and α-amylase were also improved significantly in gene deletion strains. Furthermore, the triplicate gene (dltD, clsA, and pssA) deletion strain was constructed, which further led to the 45.71 ± 2.43% increase of cell surface net negative charge and 26.45 ± 2.31% increase of cell membrane permeability, and the activities of nattokinase and α-amylase reached 37.15 ± 0.89 FU/mL and 305.3 ± 8.4 U/mL, increased by 46.09 ± 3.51% and 96.34 ± 7.24%, respectively. Taken together, our results confirmed that cell surface engineering via deleting dltD, clsA, and pssA is an efficient strategy for enhanced production of target proteins, and this research provided a promising host strain of B. licheniformis for efficient protein expression.

中文翻译：

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通过改造地衣芽孢杆菌的细胞表面，提高了异源蛋白质的产量。

细胞表面工程被证明是增强目标代谢产物产生的有效策略。在这项研究中，我们希望通过工程化地衣芽孢杆菌的细胞表面来提高目标蛋白的产量。首先，我们的结果证实了D-丙氨酰-硫代磷酸合成酶基因dltD，心磷脂合成酶基因clsA和CDP-二甘油甘油-丝氨酸O-磷脂酰转移酶基因pssA的缺失不利于细胞生长，而基因缺失菌株的生物量分别是分别降低了10.54±1.43％，14.17±1.51％和17.55±1.28％，同时由于细胞表面净负电荷和细胞膜通透性的增加，总细胞外蛋白的浓度得到改善。此外，靶蛋白，纳豆激酶，α-淀粉酶和α-淀粉酶在基因缺失菌株中也显着改善。此外，构建了三重基因（dltD，clsA和pssA）缺失菌株，这进一步导致细胞表面净负电荷增加了45.71±2.43％，细胞膜通透性增加了26.45±2.31％，并且纳豆激酶活性α-淀粉酶和α-淀粉酶分别达到37.15±0.89 FU / mL和305.3±8.4 U / mL，分别增加46.09±3.51％和96.34±7.24％。两者合计，我们的结果证实，通过删除dltD，clsA和pssA进行细胞表面工程改造是提高目标蛋白产量的有效策略，这项研究为有效地表达蛋白提供了一种有前景的地衣芽孢杆菌宿主菌株。进一步导致细胞表面净负电荷增加45.71±2.43％，细胞膜通透性增加26.45±2.31％，纳豆激酶和α-淀粉酶的活性分别达到37.15±0.89 FU / mL和305.3±8.4 U / mL ，分别增加了46.09±3.51％和96.34±7.24％。两者合计，我们的结果证实，通过删除dltD，clsA和pssA进行细胞表面工程改造是提高目标蛋白产量的有效策略，这项研究为有效地表达蛋白提供了一种有前景的地衣芽孢杆菌宿主菌株。进一步导致细胞表面净负电荷增加45.71±2.43％，细胞膜通透性增加26.45±2.31％，纳豆激酶和α-淀粉酶的活性分别达到37.15±0.89 FU / mL和305.3±8.4 U / mL ，分别增加了46.09±3.51％和96.34±7.24％。两者合计，我们的结果证实，通过删除dltD，clsA和pssA进行细胞表面工程改造是提高目标蛋白产量的有效策略，这项研究为有效地表达蛋白提供了一种有前景的地衣芽孢杆菌宿主菌株。