Jin Hui, Lao Yong Min, Ying Ke Zhen, Zhou Jin, Cai Zhong Hua
Shenzhen International Graduate School, Tsinghua University, Shenzhen, China.
School of Pharmaceutical Sciences (Shenzhen), Sun Yat-sen University, Guangzhou, China.
Front Microbiol. 2020 Nov 12;11:511801. doi: 10.3389/fmicb.2020.511801. eCollection 2020.
Cyanobacterial blooms are serious environmental issues in global freshwater ecosystems. Nitrogen limitation is one of the most important strategies to control cyanobacterial blooms. However, recent researches showed that N limitation does not effectively control the bloom; oppositely, N limitation induces N-fixing cyanobacterial blooms. The mechanism underlying this ecological event is elusive. In this study, we found that N limitation enhances stress tolerance of by triggering stringent response (SR), one of the most important bacterial adaptive responses to environmental stresses. Initiation of SR exerted protective effects on the cells against salt and oxidative stresses by promoting colony formation, maintaining membrane integrity, increasing photosynthetic performance, reducing ROS production, upregulating stress-related genes, etc. These protections possibly help maintain their population number during seasonal N limitation. As SR has been proven to be involved in nitrogen fixing under N limitation conditions, the potential role of SR in driving the shift and succession of cyanobacterial blooms was discussed. Our findings provide cellular evidence and possible mechanisms that reducing N input is ineffective for bloom control.
蓝藻水华是全球淡水生态系统中严重的环境问题。氮限制是控制蓝藻水华最重要的策略之一。然而，最近的研究表明，氮限制并不能有效控制水华；相反，氮限制会引发固氮蓝藻水华。这一生态事件背后的机制尚不清楚。在本研究中，我们发现氮限制通过触发严格反应（SR）增强了[某种生物，原文未明确]的胁迫耐受性，严格反应是细菌对环境胁迫最重要的适应性反应之一。严格反应的启动通过促进菌落形成、维持膜完整性、提高光合性能、减少活性氧产生、上调胁迫相关基因等对细胞发挥抗盐和抗氧化胁迫的保护作用。这些保护作用可能有助于[某种生物，原文未明确]在季节性氮限制期间维持其种群数量。由于严格反应已被证明在氮限制条件下参与固氮作用，因此讨论了严格反应在驱动蓝藻水华转变和演替中的潜在作用。我们的研究结果提供了细胞层面的证据和可能的机制，表明减少氮输入对控制水华无效。
