Ligand-induced system plays an important role for microbial engineering due to its tunable gene expression control over timings and levels. An oleic acid (OA)-induced system was recently constructed based on protein FadR, a transcriptional regulator involved in fatty acids metabolism, for metabolic control in Escherichia coli. In this study, we constructed a synthetic FadR-based OA-induced systems in Halomonas bluephagenesis by hybridizing the porin promoter core region and FadR-binding operator (fadO). The dynamic control range was optimized over 150-fold, and expression leakage was significantly reduced by tuning FadR expression and positioning fadO, forming a series of OA-induced systems with various expression strengths, respectively. Additionally, ligand orthogonality and cross-species portability were also studied and showed highly linear correlation among Halomonas spp., Escherichia coli and Pseudomonas spp. Finally, OA-induced systems with medium- and small-dynamic control ranges were employed to dynamically control the expression levels of morphology associated gene minCD, and monomer precursor 4-hydroxybutyrate-CoA (4HB-CoA) synthesis pathway for polyhydroxyalkanoates (PHA), respectively, in the presence of oleic acid as an inducer. As a result, over 10 g/L of poly-3-hydroxybutyrate (PHB) accumulated by elongated cell sizes, and 6 g/L of P(3HB-co-9.57 mol% 4HB) were obtained by controlling the dose and induction time of oleic acid only. This study provides a systematic approach for ligand-induced system engineering, and demonstrates an alternative genetic tool for dynamic control of industrial biotechnology.

配体诱导系统因其对时间和水平的可调节基因表达控制而在微生物工程中发挥重要作用。最近基于蛋白质 FadR（一种参与脂肪酸代谢的转录调节因子）构建了一种油酸 (OA) 诱导系统，用于大肠杆菌的代谢控制。在这项研究中，我们通过将孔蛋白启动子核心区域和 FadR 结合操纵子 ( fadO )杂交，构建了一个合成的基于 FadR 的 OA 诱导系统在Halomonas bluephagenesis中。动态控制范围优化超过 150 倍，通过调整 FadR 表达和定位fadO显着减少了表达泄漏，分别形成一系列具有不同表达强度的OA诱导系统。此外，还研究了配体正交性和跨物种可移植性，并在Halomonas spp中显示出高度线性相关性。，大肠杆菌和假单胞菌属。最后，利用具有中等和小动态控制范围的 OA 诱导系统动态控制形态相关基因minCD的表达水平，以及聚羟基链烷酸酯 (PHA) 的单体前体 4-羟基丁酸-CoA (4HB-CoA) 合成途径，分别在油酸作为诱导剂存在下。结果，超过 10 g/L 的聚 3-羟基丁酸酯 (PHB) 通过拉长的细胞尺寸积累，6 g/L 的 P(3HB-co -9.57 mol% 4HB) 仅通过控制油酸的剂量和诱导时间获得。本研究为配体诱导的系统工程提供了一种系统方法，并展示了一种用于工业生物技术动态控制的替代遗传工具。