The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kongens Lyngby, Denmark.
CysBio ApS, Hørsholm, Denmark.
Biotechnol Bioeng. 2020 May;117(5):1513-1524. doi: 10.1002/bit.27297. Epub 2020 Feb 18.
Inducible expression systems can be applied to control the expression of proteins or biochemical pathways in cell factories. However, several of the established systems require the addition of expensive inducers, making them unfeasible for large-scale production. Here, we establish a genome integrated trp-T7 expression system where tryptophan can be used to control the induction of a gene or a metabolic pathway. We show that the initiation of gene expression from low- and high-copy vectors can be tuned by varying the initial concentration of tryptophan or yeast extract, and that expression is tightly regulated and homogenous when compared with the commonly used lac-T7 system. Finally, we apply the trp-T7 expression system for the production of l-serine, where we reach titers of 26 g/L in fed-batch fermentation.
诱导表达系统可用于控制细胞工厂中蛋白质或生化途径的表达。然而，已建立的一些系统需要添加昂贵的诱导剂，因此不适合大规模生产。在这里，我们建立了一个基因组整合的 trp-T7 表达系统，其中色氨酸可用于控制基因或代谢途径的诱导。我们表明，通过改变色氨酸或酵母提取物的初始浓度，可以调整来自低拷贝和高拷贝载体的基因表达起始，与常用的 lac-T7 系统相比，表达受到严格调控且均匀。最后，我们将 trp-T7 表达系统应用于 l-丝氨酸的生产，在分批补料发酵中达到 26 g/L 的滴度。
