ε-Poly-L-lysine (ε-PL) is a natural food preservative, which exhibits antimicrobial activity against a wide spectra of microorganisms. The production of ε-PL was significantly enhanced by pH shock in our previous study, but the underlying mechanism is poorly understood. According to transcriptional and physiological analyses in this study, the mprA/B and pepD signal transduction system was first proved to be presented and activated in Streptomyces albulus M-Z18 by pH shock, which positively regulated the transcription of ε-PL synthetase (Pls) gene and enhanced the Pls activity during fermentation. Furthermore, pH shock changed the ratio of unsaturation to saturation fatty acid in the membrane through up-regulating the transcription of fatty acid desaturase genes (SAZ_RS14940, SAZ_RS14945). In addition, pH shock also enhanced the transcription of cytochrome c oxidase (SAZ_RS15070, SAZ_RS15075), ferredoxin reductase (SAZ_RS34975) and iron sulfur protein (SAZ_RS31410) genes, and finally resulted in the improvement of cell respiratory activity. As a result, pH shock was considered to influence a wide range of proteins including regulators, fatty acid desaturase, respiratory chain component, and ATP-binding cassette transporter during fermentation. These combined influences might contribute to enhanced ε-PL productivity with pH shock.

中文翻译：

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在转录组学水平上使用pH休克策略了解链霉菌的高ε-聚L-赖氨酸生产。

ε-聚-L-赖氨酸（ε-PL）是一种天然食品防腐剂，对多种微生物都具有抗菌活性。在我们先前的研究中，pH冲击显着增强了ε-PL的产生，但其潜在机理尚不清楚。根据这项研究中的转录和生理分析，首先证明了mprA / B和pepD信号转导系统是通过pH休克在链霉菌M-Z18中呈现并激活的，从而积极调节ε-PL合成酶（Pls）的转录基因和增强发酵过程中的Pls活性。此外，pH冲击通过上调脂肪酸去饱和酶基因（SAZ_RS14940，SAZ_RS14945）的转录而改变了膜中不饱和脂肪酸与饱和脂肪酸的比率。此外，pH冲击还增强了细胞色素C氧化酶（SAZ_RS15070，SAZ_RS15075），铁氧还蛋白还原酶（SAZ_RS34975）和铁硫蛋白（SAZ_RS31410）基因的转录，最终导致细胞呼吸活性的改善。结果，在发酵过程中，pH冲击被认为会影响多种蛋白质，包括调节剂，脂肪酸去饱和酶，呼吸链成分和ATP结合盒转运蛋白。这些综合影响可能有助于在pH冲击下提高ε-PL生产率。发酵过程中呼吸链成分和ATP结合盒转运蛋白。这些综合影响可能有助于在pH冲击下提高ε-PL生产率。发酵过程中呼吸链成分和ATP结合盒转运蛋白。这些综合影响可能有助于在pH冲击下提高ε-PL生产率。