School of Food Science and Engineering, South China University of Technology, Guangzhou 510640, China.
College of Food Science, South China Agricultural University, Guangzhou, China.
Enzyme Microb Technol. 2024 Dec;181:110520. doi: 10.1016/j.enzmictec.2024.110520. Epub 2024 Oct 1.
Dunaliella can accumulate more β-carotene (10 % or even more of the dry weight of cells) than any other species. Lycopene β-cyclase (LcyB) is the key enzyme in the catalysis of lycopene to β-carotene. In the present research, we used Escherichia coli BL21 (DE3) as host to construct two different types of engineering bacteria, one expressing the D. bardawil LcyB and the other expressing the orthologue Erwinia uredovora crtY. The catalytic ability of LcyB and CrtY were evaluated by comparing the β-carotene yields of the two E. coli BL21(DE3) strains, whose salt tolerance was simultaneously compared by cultivated them under different NaCl concentrations (1 %, 2 %, and 4 %). We also interfered with the LcyB gene to investigate the effect of LcyB in D. bardawil. Results displayed that the β-carotene yield of the LcyB-transformant significantly increased by about 48 % compared with the crtY-transformant. Additionally, LcyB was verified to be able to enhance the salt tolerance of E. coli BL21 (DE3). It is concluded that D. bardawil LcyB not only has better catalytic ability but also is able to confer salt tolerance to cells. Interfering D. bardawil LcyB induced the low expression of LcyB and the changes of growth and carotenoids metabolism in D. bardawil.
杜氏盐藻能够积累比其他任何物种更多的β-胡萝卜素（高达细胞干重的 10%甚至更多）。番茄红素β-环化酶（LcyB）是催化番茄红素生成β-胡萝卜素的关键酶。本研究以大肠杆菌 BL21（DE3）为宿主构建了两种不同类型的工程菌，一种表达杜氏盐藻 LcyB，另一种表达欧文氏菌 crtY。通过比较两种大肠杆菌 BL21（DE3）菌株的β-胡萝卜素产量来评估 LcyB 和 CrtY 的催化能力，同时通过在不同 NaCl 浓度（1%、2%和 4%）下培养来比较它们的耐盐性。我们还干扰了 LcyB 基因，以研究 LcyB 在杜氏盐藻中的作用。结果表明，与 crtY 转化体相比，LcyB 转化体的β-胡萝卜素产量显著提高了约 48%。此外，LcyB 被证实能够增强大肠杆菌 BL21（DE3）的耐盐性。结论是，杜氏盐藻 LcyB 不仅具有更好的催化能力，而且能够赋予细胞耐盐性。干扰杜氏盐藻 LcyB 会导致 LcyB 的低表达以及杜氏盐藻生长和类胡萝卜素代谢的变化。
