Microorganisms are particularly adapted to alterations in their environment. One of the global regulatory mechanisms involved in these adaptations is the stringent response. The unusual nucleotides, guanosine penta and tetraphosphates, (p)ppGpp act as alarmones of this response, heralding nutrient limitation and stressors. Marine bacteria encounter numerous stresses of sparse nutrient supplies and changes in physicochemical conditions. The aim of this work was to assess whether the stress conditions common in marine environment can induce the stringent response and what is a kinetic of this process. The representative bacterial species, Shewanella baltica, Acinetobacter johnsonii, Vibrio harveyi, and Escherichia coli were subjected to a variety of stressors. We analyzed the kinetics of (p)ppGpp synthesis by labeling in vivo nucleotides and analysis by thin layer chromatography. The (p)ppGpp accumulation followed the elevated temperature and amino acid starvation for all bacteria tested. The carbon and nitrogen limitation resulted in the response limited to V. harveyi and S. baltica. The DNA damaging agents induced the (p)ppGpp production in all strains, while osmotic stress did not result in significant alarmone synthesis. The representative marine bacteria species were shown to induce with varying extent the stringent response upon the onset of stress and limitation conditions. Importantly, the in vivo labeling and subsequent separation of the nucleotides by thin layer chromatography serves as a valid method for the analysis of the stringent response and (p)ppGpp accumulation in environmental bacteria.

中文翻译：

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海洋细菌的严格反应-在胁迫条件下评估（p）ppGpp积累。

微生物特别适合于其环境的变化。这些适应措施涉及的全球监管机制之一是严格的应对措施。不寻常的核苷酸，鸟嘌呤五磷酸和四磷酸（p）ppGpp充当了这种反应的警钟，预示着营养限制和压力源。海洋细菌遇到稀疏营养供应和物理化学条件变化的许多压力。这项工作的目的是评估在海洋环境中常见的压力条件是否可以引起严格的响应以及该过程的动力学。代表性细菌种类有波罗的海希瓦氏菌，约翰逊不动杆菌，哈维弧菌和大肠埃希氏菌遭受了各种压力。我们通过标记体内核苷酸并通过薄层色谱分析来分析（p）ppGpp合成的动力学。（p）ppGpp积累随温度升高和所有测试细菌的氨基酸饥饿而增加。碳和氮的限制导致响应仅限于哈氏弧菌和波罗的海葡萄球菌。DNA破坏剂诱导所有菌株中的（p）ppGpp产生，而渗透胁迫并未导致明显的警报酮合成。代表性的海洋细菌物种显示出在压力和限制条件发生时在不同程度上诱导严格的响应。重要的是，在体内标记和随后通过薄层色谱法分离核苷酸的方法是分析环境细菌中严格应答和（p）ppGpp积累的有效方法。