Crocins are highly valuable medicinal compounds for treating human disorders, and they also serve as spices and coloring agents. However, the supply of crocins from plant extractions is insufficient for current demands, and using synthetic biology to produce crocins remains a big challenge. Here, we report the in vivo production of five types of crocins in E. coli with GjUGT94E13 and GjUGT74F8, which are responsible for the glycosylation of crocetin, from the crocin-producing plant Gardenia jasminoides. Subsequently, native UDP-glucose biosynthesis in E. coli is strengthened by the overexpression of pgm and galU. The optimization of catalytic reactions has demonstrated that 50 mM NaH2PO4-Na2HPO4 buffer (pH 8.0) plus 5% glucose is the best medium to use for the efficient glycosylation of crocetin. In engineered E. coli, the conversion rate of crocin III and crocin V from crocetin (50 mg/L) by the catalysis of GjUGT74F8 was increased to 66.1%, and the conversion rate of five types of crocins from crocetin (50 mg/L) via GjUGT94E13 and GjUGT74F8 was 59.6%, much higher than the catalytic activity of the reported microbial UGTs. This study not only sheds light on the in vivo biosynthesis of crocins in E. coli, but also provides important genetic tools for the de novo synthesis of crocins.

中文翻译：

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在工程化大肠杆菌中体内生产五种红霉素。

藏红花是用于治疗人类疾病的极有价值的药用化合物，它们还可以用作香料和着色剂。然而，从植物提取物中提供的番红花素不足以满足当前的需求，并且利用合成生物学生产番红花素仍是一个巨大的挑战。在这里，我们报道了大肠杆菌的GjUGT94E13和GjUGT74F8在大肠杆菌中的体内生产五种类型的番红花素，它们负责生产番红花素的植物Garden子茉莉花苷，从而导致番红花素的糖基化。随后，通过pgm和galU的过度表达增强了大肠杆菌中的天然UDP-葡萄糖生物合成。催化反应的优化表明，50 mM NaH2PO4-Na2HPO4缓冲液（pH 8.0）加5％葡萄糖是用于大黄素有效糖基化的最佳培养基。在工程大肠杆菌中 通过GjUGT74F8的催化作用，将大黄素（50 mg / L）中的crocin III和crocin V的转化率提高到66.1％，通过GjUGT94E13和GjUGT74F8从5种大黄素（50 mg / L）中转化的番红素的转化率为59.6％，远高于已报道的微生物UGTs的催化活性。这项研究不仅揭示了大肠杆菌中番红花的体内生物合成，而且还为从头合成番红花提供了重要的遗传工具。