Abstract

Bacterial populations rely on quorum sensing (QS) to coordinate their behaviors and are often challenged by the fluctuation in oxygen concentrations in their habitats. Oxygen is a crucial factor that affects bacterial metabolism in multiple ways. However, little is known about whether and how oxygen availability affects QS activities. To fill this gap, we used the facultative anaerobe Novosphingobium pentaromativorans US6-1 as a model system, and observed that the QS signal acyl homoserine-lactones (AHLs) were produced only in anoxic environments, such as biofilm, or liquid medium that initially contained less than 2 mg/L dissolved oxygen, but not in highly oxic environments. Comparative transcriptome analysis revealed that oxygen availability significantly affected the physiological activities in US6-1, including fatty acid metabolism, oxidative phosphorylation, citrate cycle, QS activities, and flagellar assembly. The absence of AHLs in the oxic culture was not due to degradation, but to the very low expression of the AHL synthase gene novI. High concentration of NADH during the middle log phase under static cultivation may be a trigger for AHL synthesis. This is the first report that production of AHLs is coupled with anoxic metabolism in a facultative anaerobe, which extends our knowledge on factors affecting bacterial QS occurrence.

Key points

• AHL production is anoxic cultivation related.

• Oxygen availability affects AHL synthesis by influencing novI expression.

• Oxygen availability changes many metabolism activities including NADH production.

中文翻译：

---

氧的可用性会影响兼性厌氧性新孢子虫五氧化氮US6-1中群体感应信号的合成。

摘要

细菌种群依靠群体感应（QS）来协调其行为，并且常常受到其栖息地氧气浓度波动的挑战。氧气是通过多种方式影响细菌代谢的关键因素。但是，关于氧气的供应是否以及如何影响QS活动知之甚少。为了填补这一空白，我们使用了兼性厌氧性新孢子虫以US6-1作为模型系统，并观察到QS信号酰基高丝氨酸-内酯（AHL）仅在缺氧环境下产生，例如生物膜或最初包含低于2 mg / L溶解氧的液体介质，但在高氧环境。对比转录组分析显示，氧的利用显着影响了US6-1中的生理活性，包括脂肪酸代谢，氧化磷酸化，柠檬酸循环，QS活性和鞭毛组装。在有氧培养物中不存在AHL并不是由于降解，而是由于AHL合酶基因novI的极低表达。在静态培养的对数中期，NADH的高浓度可能是AHL合成的诱因。这是关于在兼性厌氧菌中AHL的产生与缺氧代谢相结合的首次报道，这扩展了我们对影响细菌QS发生的因素的认识。

关键点

• AHL的生产与缺氧栽培有关。

•氧气可用性通过影响novI表达影响AHL合成。

•氧气供应量改变了许多代谢活动，包括NADH的产生。