Coevolution in complex communities: exploring the formation, stability and the importance of microbial communities within their hosts.

复杂群落中的共同进化：探索宿主内微生物群落的形成、稳定性和重要性。

• 批准号: NE/K00879X/1
• 负责人: Britt Koskella
• 金额: $ 72.68万
• 依托单位: UNIVERSITY OF EXETER
• 依托单位国家: 英国
• 项目类别: Fellowship
• 财政年份: 2013
• 资助国家: 英国
• 起止时间: 2013 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FK00879X%2F1
• 关键词: Coevolution; complex; communities; exploring; formation

It is now clear that plants and animals, including man, harbor many more microbial cells than their own cells. The microbes living in and on a host are much more than a random assortment of bacteria that happen to colonize it. Instead, they form a complex community (the so called "microbiota") of bacteria that are interacting with one another, with the host, and also with bacteriophage viruses that infect them. What is less clear, however, is what makes a community of microbes successful within a host, and why one host's community is so different from another. It could be the result of chance colonization of some microbes on one host and others on another host. However, it could also be due to ongoing coevolution within the host, where bacteria and their phages are adapting to resist/infect one another and, in doing so, becoming more and more different from communities within other hosts.Key to understanding the role of coevolution in generating this diversity is insight to how specific phages are to their bacterial hosts. Can phages adapt to infect new bacterial types as they become common? Can the same phage type shift from one bacterial species to another? The most powerful way to address these knowledge gaps is using experimental coevolution, where microbes and phages are grown together in a test tube and sampled over time to monitor evolutionary change. This approach has offered key advances in our understanding of the evolution of bacterial resistance to phages and reciprocal adaptations of phages to overcome such resistance. However, there are many reasons that the outcome of coevolution in a test tube might not be predictive of coevolution in nature; especially within a host that is itself mounting an immune response to keep bacteria at bay. I plan to use interactions among plants, their bacteria - both harmless and harmful - and their pathogens (bacteriophages) as a model system to examine the role of the plant host immune system in shaping its microbiota, the role of the microbiota in influencing the fitness of the plant host, and the role of phages in driving dynamic changes in these microbial communities over time.To understand the importance of these coevolutionary interactions in nature, I am focusing on microbes living within the leaves of horse chestnut trees in the UK. These trees are currently under threat from an emerging bacterial pathogen, Pseudomonas syringae, that causes bleeding canker disease. Thus, understanding how their natural microbial communities and phages in the environment influence the tree's susceptibility to disease is of clear applied interest. Once I have an idea of the natural diversity of microbiota and the influence of these communities on host health, I will experimentally test the coevolutionary interactions among bacteria and their phages in the host. This will be done using experimental coevolution within tomato plant hosts, which also suffer from attack by P. syringae. Using the plant as a natural test tube, I will manipulate the number and type of bacteria the host harbors and measure coevolutionary change in real time within the host. The study of microbiota is particularly important as there is now intriguing evidence that these bacteria can act as a first line of defense against disease. This microbiota-mediated resistance could be the result of the exclusion of newly colonizing bacteria by those that are already well-adapted to the host (i.e., the microbiotia) or it could be the result of coevolution with bacteriophage viruses, as bacteria within the host are likely to have evolved increased resistance to their local pathogens while newly-arriving bacteria may still be susceptible to infection. I will use the tomato-bacteria-phage system to explicitly test the underlying mechanism of protection conferred by microbiota to their hosts and the role that phages might play in altering the establishment and progression of disease.

现在很清楚，植物和动物，包括人类，比它们自己的细胞拥有更多的微生物细胞。生活在宿主体内和宿主表面的微生物远不止是随机分布的细菌，而是形成了一个复杂的细菌群落（所谓的“微生物群”），这些细菌相互作用，与宿主相互作用，也与感染它们的噬菌体病毒相互作用。然而，不太清楚的是，是什么使微生物群落在宿主体内成功，以及为什么一个宿主的群落与另一个宿主如此不同。它可能是某些微生物在一个宿主上偶然定殖而另一些在另一个宿主上偶然定殖的结果。然而，这也可能是由于宿主内正在进行的共同进化，其中细菌和它们的寄生虫正在适应彼此抵抗/感染，并且在这样做的过程中，变得越来越不同于其他宿主内的社区。理解共同进化在产生这种多样性中的作用的关键是了解寄生虫对细菌宿主的特异性。当新的细菌类型变得普遍时，细菌是否能适应感染它们？相同的噬菌体类型可以从一种细菌物种转移到另一种细菌物种吗？解决这些知识差距的最有效方法是使用实验性的共同进化，即微生物和微生物在试管中一起生长，并随着时间的推移进行采样以监测进化变化。这种方法提供了关键的进展，我们的理解细菌耐药性的演变，以克服这种阻力和互惠的适应性的细菌。然而，有很多原因表明，试管中的共同进化结果可能无法预测自然界中的共同进化;特别是在一个自身正在建立免疫反应以阻止细菌的宿主中。我计划利用植物、它们的细菌（包括无害的和有害的）以及它们的病原体之间的相互作用（噬菌体）作为模型系统来检查植物宿主免疫系统在塑造其微生物群中的作用，微生物群在影响植物宿主的适应性中的作用，以及细菌在驱动这些微生物群落随时间发生动态变化中的作用。为了了解这些共同进化相互作用在在自然界，我专注于生活在英国七叶树树叶中的微生物。这些树木目前正受到一种新出现的细菌病原体的威胁，这种病原体是假单胞菌，会引起出血性溃疡病。因此，了解它们的自然微生物群落和环境中的微生物如何影响树木对疾病的易感性具有明显的应用价值。一旦我了解了微生物群的自然多样性以及这些群落对宿主健康的影响，我将通过实验测试细菌及其宿主之间的共同进化相互作用。这将使用番茄植物宿主内的实验性共同进化来完成，番茄植物宿主也遭受P. dumingae的攻击。利用植物作为一个天然的试管，我将操纵宿主体内细菌的数量和类型，并测量宿主体内真实的共同进化的变化。微生物群的研究尤其重要，因为现在有有趣的证据表明这些细菌可以作为抵御疾病的第一道防线。这种微生物群介导的抗性可能是那些已经很好地适应宿主的细菌（即，也可能是与噬菌体病毒共同进化的结果，因为宿主体内的细菌可能已经进化出对当地病原体的抵抗力，而新到达的细菌可能仍然容易受到感染。我将使用番茄-细菌-噬菌体系统来明确测试微生物群对其宿主的潜在保护机制，以及微生物群在改变疾病的建立和进展中可能发挥的作用。

项目成果

The evolution of bacterial resistance against bacteriophages in the horse chestnut phyllosphere is general across both space and time.

• DOI: 10.1098/rstb.2014.0297
• 发表时间: 2015-08-19
• 期刊: Philosophical transactions of the Royal Society of London. Series B, Biological sciences
• 作者: Koskella B;Parr N
• 通讯作者: Parr N

Bacteria-phage coevolution as a driver of ecological and evolutionary processes in microbial communities.

• DOI: 10.1111/1574-6976.12072
• 发表时间: 2014-09
• 期刊: FEMS microbiology reviews
• 影响因子: 11.3
• 作者: Koskella B;Brockhurst MA
• 通讯作者: Brockhurst MA

The cost of phage resistance in a plant pathogenic bacterium is context-dependent.

• DOI: 10.1111/evo.12652
• 发表时间: 2015-05
• 期刊: Evolution; international journal of organic evolution
• 作者: Meaden S;Paszkiewicz K;Koskella B
• 通讯作者: Koskella B

Friend and foe: factors influencing the movement of the bacterium Helicobacter pylori along the parasitism-mutualism continuum.

朋友和敌人：影响幽门螺杆菌沿着寄生-互惠连续体运动的因素。

• DOI: 10.1111/eva.12231
• 发表时间: 2015
• 期刊: Evolutionary applications
• 影响因子: 4.1
• 作者: Lin D

Understanding Adaptation and Diversification: Insights from the Study of Microbial Experimental Evolution.

了解适应和多样化：微生物实验进化研究的见解。

• DOI: 10.1111/evo.12564
• 发表时间: 2014
• 期刊: Evolution; international journal of organic evolution
• 作者: Koskella B