To kill or not to kill: deciphering the metabolic triggers of a facultative algicidal bacterium Ponticoccus. (4565)

硅藻占全球初级生产的20%，支持主要渔业，是大气CO2上升的主要汇。这些生物也具有作为生产高价值产品和生物燃料的原料的巨大潜力。因此，更好地了解控制硅藻生长、生理和代谢的因素至关重要。我们越来越意识到硅藻和其他微生物之间的生物相互作用在调节硅藻生长方面的重要性，尽管很少有人直接表征。这个项目建立在我们最近的环境调查基础上，以发现与硅藻相互作用的细菌。这项工作导致了一个兼性溶藻细菌，Ponticoccus的鉴定，它可以杀死硅藻在一个物种特异性的mays.Our实验表明，溶藻的生活方式Ponticoccus的激活只有在一定的生长条件下，这表明代谢开关控制这种细菌的致病性。然而，我们目前还不了解P. alexandii如何导致硅藻细胞死亡，什么机制控制了致病性生活方式的转变，或者这些机制在不同的溶藻细菌中如何保守。这个博士将使用我们的新模型系统i）进行一系列藻-细菌共培养实验，以确定控制细菌致病性的环境信号机制，ii）采用生物化学和代谢组学方法来解释杀藻活性的分子基础，（三）研究现有的基因组和转录组数据集，以评估在Ponticoccus和其他拮抗细菌中溶藻途径的存在和保护。这项工作将大大促进对环境因素如何塑造自然的理解。本项目的目的是研究海洋微生物之间的生物相互作用，并对这种相互作用的分子机制提供重要的新见解，通过研究拮抗性藻-菌相互作用的机理基础，将为医药和生物技术领域的新型抗菌剂的鉴定提供指导。此外，这项工作将提供与环境相关的藻类-细菌相互作用的基本新见解，这些相互作用可能是海洋碳循环的重要驱动力。最后，该项目提供了一个令人兴奋的机会，可以利用埃克塞特大学和MBA的各种专业知识，在微生物学，基因组学，生理学，代谢和生物化学等广泛的实验室技术方面获得培训。

Diatoms account for 20% of global primary production, support key fisheries, and are a major sink for rising atmospheric CO2. These organisms also have great potential as a feedstock for the production of high-valueproducts and biofuel. It is thus critical to better understand factors controlling diatom growth, physiology andmetabolism. We are becoming increasingly aware of the importance of biotic interactions between diatoms andother microbes in regulating diatom growth, although very few have been characterised directly.This project builds on our recent environmental survey to discover bacteria that interact with diatoms. This work led to the identification of a facultative algicidal bacterium, Ponticoccus, which can kill diatoms in a species-specific manner.Our experiments have shown that the algicidal lifestyle of Ponticoccus is activated only under certain growth conditions, suggesting that a metabolic switch controls pathogenicity of this bacterium. However, we currently do not understand how P. alexandrii causes diatom cell death, what mechanisms govern the switch to a pathogenic lifestyle, or how conserved such mechanisms are across different algicidal bacteria.This PhD will employ our new model system to i) conduct a range of algal-bacterial co-culture experiments to determine the environmental signalling mechanisms controlling bacterial pathogenicity, ii) employ biochemical and metabolomics approaches to decipher the molecular basis for algicidal activity, iii) examine existing genome and transcriptome datasets to assess the presence and conservation of algicidal pathways in Ponticoccus and other antagonist bacteria.This work will significantly advance understanding of how environmental factors shape the nature of biotic interactions between marine microbes, and provide important new insight of the molecular mechanisms underlying of such interactions.By studying the mechanistic basis of antagonistic algal-bacterial interactions, this project could lead to the identification of novel anti-microbials for medicine and biotechnology. Additionally, this work will provide fundamental new insight of environmentally relevant algal-bacterial interactions that are likely a significant driver of ocean carbon cycling.Finally, this project offers an exciting opportunity to gain training in a broad range of laboratory techniques spanning microbiology, genomics, physiology, metabolism and biochemistry, utilising diverse expertise from the University of Exeter and MBA.