PDF(Pubmed)
Abstract：
Hydroxyectoine is an important compatible solute that holds potential for development into a high-value chemical with broad applications. However, the traditional high-salt fermentation for hydroxyectoine production presents challenges in treating the high-salt wastewater. Here, we report the rational engineering of Halomonas salifodinae to improve the bioproduction of hydroxyectoine under lower-salt conditions. The comparative transcriptomic analysis suggested that the increased expression of ectD gene encoding ectoine hydroxylase (EctD) and the decreased expressions of genes responsible for tricarboxylic acid (TCA) cycle contributed to the increased hydroxyectoine production in H. salifodinae IM328 grown under high-salt conditions. By blocking the degradation pathway of ectoine and hydroxyectoine, enhancing the expression of ectD, and increasing the supply of 2-oxoglutarate, the engineered H. salifodinae strain HS328-YNP15 (ΔdoeA::PUP119-ectD p-gdh) produced 8.3-fold higher hydroxyectoine production than the wild-type strain and finally achieved a hydroxyectoine titer of 4.9 g/L in fed-batch fermentation without any detailed process optimization. This study shows the potential to integrate hydroxyectoine production into open unsterile fermentation process that operates under low-salinity and high-alkalinity conditions, paving the way for next-generation industrial biotechnology. KEY POINTS: • Hydroxyectoine production in H. salifodinae correlates with the salinity of medium • Transcriptomic analysis reveals the limiting factors for hydroxyectoine production • The engineered strain produced 8.3-fold more hydroxyectoine than the wild type.
摘要：
羟甲妥因是一种重要的相容性溶质，具有开发成为具有广泛应用价值的高价值化学品的潜力。然而,传统的高盐发酵生产羟基异黄酮对高盐废水的处理提出了挑战。这里,我们报道了在低盐条件下对唾液Halomonassalifodinae进行的合理工程，以提高羟基艾托宁的生物生产。比较转录组分析表明，编码ectoine羟化酶（EctD）的ectD基因的表达增加和负责三羧酸（TCA）循环的基因的表达减少导致了在高盐条件下生长的H.salifodinaeIM328中羟基ectoine的产生增加。通过阻断艾克托因和羟基艾克托因的降解途径，增强ectD的表达，增加2-氧戊二酸的供应，工程H.salifodinae菌株HS328-YNP15（ΔdoeA：：PUP119-ectDp-gdh）产生的羟基艾托因产量比野生型菌株高8.3倍，最终在补料中达到了4.9g/L的羟基艾托因滴度。分批发酵没有任何详细的过程优化。这项研究表明，将羟基艾托宁生产整合到在低盐度和高碱度条件下运行的开放式非无菌发酵过程中的潜力，为下一代工业生物技术铺平道路。关键点:•在H.salifodinae中的羟基胞嘧啶的产生与培养基的盐度相关•转录组学分析揭示了羟基胞嘧啶产生的限制因素•工程菌株产生的羟基胞嘧啶比野生型多8.3倍。
