Intra- and interspecific siderophore cheating in bacteria

细菌种内和种间铁载体作弊

• 批准号: 1616967
• 负责人: Martin Schuster
• 金额: $ 56.92万
• 依托单位: Oregon State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-08-01 至 2021-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1616967&HistoricalAwards=false
• 关键词: Intra; interspecific; siderophore; cheating; bacteria

The goal of this project is to study mechanisms that help maintain cooperative iron acquisition in bacterial communities. Cooperative iron acquisition is crucial to the survival of many microbial communities, but it is vulnerable to exploitation by social cheaters that reap the benefits of iron acquisition without paying the cost. Cooperative iron acquisition is widespread in microbial communities, including communities that are important for soil ecology, agriculture, and medicine. This work will provide important information about the conditions and circumstances that stabilize such communities and general information about how more complex communities are stabilized. This project will contribute to the training and career development of students at the graduate, undergraduate and high school levels.Much has been learned about the molecular mechanisms of microbial cooperative behaviors such as biofilm formation, virulence, and nutrient acquisition. However, only recently have microbiologists also begun to investigate these behaviors from the perspective of social evolution. The focus of this project is on the evolutionary stability of cooperative iron acquisition in pseudomonads. Several Pseudomonas species acquire iron by secreting pyoverdines, a structurally diverse class of non-ribosomal peptide siderophores that are internalized by cognate receptors. The evolutionary stability of pyoverdine cooperation is challenged by intraspecific cheating between P. aeruginosa pyoverdine producers and non-producers, and by interspecific cheating between two Pseudomonas species, P. aeruginosa and P. protegens, in which the latter recognizes the pyoverdine produced by the former but not vice versa. Both cases involve the potential exploitation of cooperative pyoverdine production by cells that reap the benefits without paying the costs. Based on preliminary experimental and modeling data, it is hypothesized that bacterial growth physiology, specifically the nature of the growth-rate limiting nutrient, and asymmetric competition, specifically pyoverdine receptor affinity, are two important factors that determine the costs and benefits of cheating. These hypotheses will be tested with a combination of modeling and experimental work. Modeling will involve whole-genome metabolic models and dynamic population growth models. Experimental work will involve batch and chemostat growth of single and co-cultures under defined nutrient conditions, as well as measurements of pyoverdine receptor binding affinities and expression levels. These studies will provide insights into the mechanisms that contribute to the evolutionary stability of cooperative iron acquisition. Cooperative iron acquisition and other microbial social behaviors are of great relevance to natural ecosystems and have implications for the evolution of sociality in general. Graduate, Undergraduate and high school students will be trained in a wide range of skills in microbial genetics, physiology, biochemistry, evolutionary biology, and mathematical modeling. High school students will be hosted through the Apprenticeship for Science and Engineering, a summer internship program at Oregon State University.

该项目的目标是研究有助于维持细菌群落中合作铁获取的机制。合作铁的获取对许多微生物群落的生存至关重要，但它容易受到社会骗子的剥削，这些骗子在不支付成本的情况下获得铁获取的好处。合作性铁获取在微生物群落中广泛存在，包括对土壤生态学、农业和医学重要的群落。这项工作将提供关于稳定这些社区的条件和情况的重要信息，以及关于如何稳定更复杂社区的一般信息。本项目将有助于研究生、本科生和高中生的培训和职业发展。对微生物合作行为的分子机制，如生物膜形成、毒力和营养获取，有了很大的了解。然而，直到最近微生物学家才开始从社会进化的角度研究这些行为。这个项目的重点是在假单胞菌合作铁收购的进化稳定性。几种假单胞菌通过分泌绿脓菌荧光素获得铁，绿脓菌荧光素是一类结构多样的非核糖体肽铁载体，由同源受体内化。绿脓菌荧光素合作的进化稳定性受到铜绿假单胞菌绿脓菌荧光素生产者和非生产者之间的种内欺骗以及两种假单胞菌物种铜绿假单胞菌和保护假单胞菌之间的种间欺骗的挑战，其中后者识别由前者产生的绿脓菌荧光素，但反之亦然。这两种情况都涉及通过细胞合作生产绿脓菌荧光素的潜在利用，这些细胞在不支付成本的情况下获得利益。基于初步的实验和建模数据，假设细菌生长生理学，特别是生长速率限制营养素的性质，和不对称竞争，特别是绿脓菌荧光素受体亲和力，是决定欺骗的成本和收益的两个重要因素。这些假设将与建模和实验工作相结合进行测试。建模将涉及全基因组代谢模型和动态种群增长模型。实验工作将涉及在限定的营养条件下单一和共培养物的分批和恒化器生长，以及绿脓菌荧光素受体结合亲和力和表达水平的测量。这些研究将有助于深入了解合作铁收购的进化稳定性的机制。合作铁的收购和其他微生物的社会行为是非常相关的自然生态系统，并具有社会性的进化一般的影响。研究生、本科生和高中生将接受微生物遗传学、生理学、生物化学、进化生物学和数学建模方面的广泛技能培训。高中生将通过科学和工程学徒，在俄勒冈州州立大学夏季实习计划主办。