Microbial phenazines are getting increasing attention for antimicrobial and biotechnological applications. Phenazine production of the most well-known producer Pseudomonas aeruginosa is subject to a highly complex regulation network involving both quorum sensing and catabolite repression. These networks affect the expression of the two redundant phz gene operons responsible for phenazine-1-carboxylate (PCA) production and two specific genes phzM and phzS necessary for pyocyanin production. To decipher the specific functionality of these genes, in this study, specific phenazine gene deletion mutants of P. aeruginosa PA14 were generated and characterized in glucose and 2,3-butanediol media. Phenazine concentration and expression levels of the remaining genes were analyzed in parallel experiments. The findings suggest a strong dominance of operon phzA2-G2 resulting in a 10-fold higher expression of phz2 compared to phzA1-G1 and almost exclusive production of PCA from this operon. The genes phzM and phzS seem to exhibit antagonistic function in phenazine production. An upregulation of phzM explains the documented enhanced pyocyanin production in a 2,3-butanediol medium. Applied to a bioelectrochemical system, the altered phenazine production of the mutant strains is directly translated into current generation. Additionally, the deletion of the phenazine genes induced the activation of alternative energy pathways, which resulted in the accumulation of various fermentation products. Overall, modulating the genetic repertoire of the phenazine genes tremendously affects phenazine production levels, which are naturally kept in tight homeostasis in the P. aeruginosa wildtype. This important information can be directly utilized for ongoing efforts of heterologous biotechnological phenazine production.

中文翻译：

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通过调节遗传库来控制假单胞菌吩嗪的生产

微生物吩嗪在抗菌和生物技术应用中越来越受到关注。最著名的铜绿假单胞菌生产的吩嗪受到高度复杂的调控网络的控制，涉及群体感应和分解代谢物抑制。这些网络影响负责生产吩嗪-1-羧酸盐（PCA）的两个冗余phz基因操纵子的表达，以及影响生成蓝绿色素的两个特定基因phzM和phzS的表达。为了破译这些基因的特定功能，在这项研究中，铜绿假单胞菌的特定吩嗪基因缺失突变体生成PA14，并在葡萄糖和2,3-丁二醇培养基中进行表征。在平行实验中分析了吩嗪浓度和其余基因的表达水平。这些发现表明，操纵子phzA2-G2具有很强的优势，与phzA1-G1相比，导致phz2的表达高10倍，并且从该操纵子中几乎独家生产PCA。phzM和phzS基因似乎在吩嗪生产中表现出拮抗作用。phzM的上调解释了在2,3-丁二醇介质中记录的增强的洋青素产量。应用于生物电化学系统后，突变菌株中吩嗪产量的改变直接转化为当代。此外，吩嗪基因的缺失诱导了替代能源途径的激活，从而导致各种发酵产物的积累。总体而言，调节吩嗪基因的遗传库极大地影响了吩嗪的生产水平，而吩嗪的生产水平自然保持在铜绿假单胞菌野生型的紧密稳态中。该重要信息可直接用于正在进行的异源生物技术吩嗪生产。