Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi, Jiangsu 214122, China.
Science Center for Future Foods, Jiangnan University, Wuxi, Jiangsu 214122, China.
J Agric Food Chem. 2024 Nov 13;72(45):25186-25196. doi: 10.1021/acs.jafc.4c07609. Epub 2024 Oct 31.
7-Dehydrocholesterol (7-DHC), a direct precursor of vitamin D3, has attracted increasing attention in microbial fermentation recently. In this study, 7-DHC biosynthesis in diploid with robust ergosterol production was achieved by heterologous 24-dehydrocholesterol reductase expression, generating 44.1 mg/L 7-DHC, whereas the titer of ergosterol decreased by 40.5%. The ergosterol biosynthetic pathway was completely blocked by knocking out and , affording a 4.2-fold increase in the 7-DHC titer. Subsequently, the facilitation of the mevalonate and the postsqualene pathways accompanied by elimination of transcriptional repressors enhanced 7-DHC synthesis, and the 7-DHC titer reached 738.5 mg/L in a shake flask. Further validation in a 50 L fermenter demonstrated that the 7-DHC titer reached 3.80 g/L within just 24 h, with productivity reaching 158.3 mg/L/h, setting a new benchmark as the highest reported to date. This study paves the way toward a large-scale and cost-effective manufacture of 7-DHC.
7-去氢胆固醇（7-DHC）是维生素 D3 的直接前体，最近在微生物发酵中受到越来越多的关注。在这项研究中，通过异源表达 24-去氢胆固醇还原酶，二倍体 实现了 7-DHC 的生物合成，生成了 44.1 mg/L 的 7-DHC，而麦角固醇的产量下降了 40.5%。敲除 和 后，麦角固醇生物合成途径被完全阻断，7-DHC 的产量增加了 4.2 倍。随后，促进甲羟戊酸和鲨烯后体途径并消除转录阻遏物，增强了 7-DHC 的合成，在摇瓶中 7-DHC 的产量达到 738.5 mg/L。在 50 L 发酵罐中的进一步验证表明，7-DHC 的产量在短短 24 小时内达到 3.80 g/L，产率达到 158.3 mg/L/h，创下了迄今为止报道的最高纪录。这项研究为大规模、经济高效地生产 7-DHC 铺平了道路。
