Yu Junxiong, Liu Hao, Wang Yudi, Ju Runlin, Zhang Yue, Moshin Ali, Zhuang Yingping, Guo Meijin, Wang Zejian
State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Meilong Rd, Shanghai, 200237, China.
Synth Syst Biotechnol. 2025 Jul 17;10(4):1242-1256. doi: 10.1016/j.synbio.2025.07.004. eCollection 2025 Dec.
, a moderately halophilic γ-proteobacterium of industrial interest, serves as a microbial cell factory for ectoine-a high-value compatible solute extensively utilized in biopharmaceuticals and cosmetics. While its ectoine biosynthesis potential is well-documented, the systemic metabolic adaptations underlying osmoadaptation remain poorly characterized, limiting rational engineering strategies for optimized production. To address this gap, we employed chemostat cultivation coupled with multi-omics integration (physiological profiling, metabolomics, and metabolic flux analysis) to dissect salt-dependent metabolic network rewiring in the model strain DSM 2581 under moderate (6.0 % NaCl) and high salinity (13.0 % NaCl) Results demonstrated that, under moderate salt conditions, a specific growth rate () of 0.20 h significantly enhanced the ectoine-specific production rate ( ), intracellular ectoine content ( ), and yield coefficient ( ), concurrent with redirection of carbon flux toward the Entner-Doudoroff (ED) pathway and ectoine biosynthesis. Under high salt conditions, flux through both the ED pathway and ectoine biosynthesis was further upregulated, whereas fluxes through the pentose phosphate (PP) pathway, tricarboxylic acid (TCA) cycle, and CO generation were downregulated. Simultaneously, suppression of the flux from malate to pyruvate enhanced oxaloacetate synthesis, thereby increasing the supply of key precursors including glutamate, aspartate, and NADPH to fuel ectoine biosynthesis. Stepwise salt reduction experiments revealed bidirectional metabolic flexibility: elevated salinity prioritized carbon investment into ED-driven ectoine production, whereas hypo-osmotic conditions reactivate respiratory activity and the TCA cycle to fuel energy metabolism. These findings establish as a paradigm of dynamic flux rewiring, where carbon economy is strategically reallocated between stress-protective solute biosynthesis and energy homeostasis. This study bridges the knowledge gap in understanding the physiological characteristics of and provides a foundation for improving ectoine production and engineering strains through metabolic optimization.
作为一种具有工业价值的中度嗜盐γ-变形菌，它可作为一种微生物细胞工厂来生产依克多因——一种在生物制药和化妆品中广泛应用的高价值相容性溶质。虽然其依克多因生物合成潜力已有充分记载，但渗透适应背后的系统代谢适应性仍知之甚少，这限制了优化生产的合理工程策略。为了填补这一空白，我们采用恒化器培养结合多组学整合（生理分析、代谢组学和代谢通量分析）来剖析模式菌株DSM 2581在中度（6.0% NaCl）和高盐度（13.0% NaCl）条件下盐依赖性代谢网络的重新布线。结果表明，在中度盐条件下，0.20 h⁻¹的比生长速率显著提高了依克多因比生产率、细胞内依克多因含量和产率系数，同时碳通量重新导向磷酸酮糖途径（ED）和依克多因生物合成。在高盐条件下，通过ED途径和依克多因生物合成的通量进一步上调，而通过戊糖磷酸途径（PP）、三羧酸（TCA）循环和CO₂生成的通量则下调。同时，从苹果酸到丙酮酸的通量抑制增强了草酰乙酸的合成，从而增加了包括谷氨酸、天冬氨酸和NADPH在内的关键前体的供应，以促进依克多因生物合成。逐步降低盐浓度的实验揭示了双向代谢灵活性：盐度升高优先将碳投入到由ED驱动的依克多因生产中，而低渗条件则重新激活呼吸活性和TCA循环以促进能量代谢。这些发现确立了[菌株名称未给出]作为动态通量重新布线的范例，即碳经济在应激保护溶质生物合成和能量稳态之间进行战略重新分配。本研究填补了在理解[菌株名称未给出]生理特性方面的知识空白，并为通过代谢优化提高依克多因产量和构建工程菌株提供了基础。
