Intra- and inter-specific competition and the evolution of cooperation in Bacillus thuringiensis

苏云金芽孢杆菌种内和种间竞争与合作的演变

• 批准号: NE/E012671/1
• 负责人: Benjamin Raymond
• 金额: $ 63.56万
• 依托单位: University of Oxford
• 依托单位国家: 英国
• 项目类别: Fellowship
• 财政年份: 2007
• 资助国家: 英国
• 起止时间: 2007 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FE012671%2F1
• 关键词: Intra; inter; specific; competition; evolution

Cooperation is a common feature of bacterial lifestyles. This may be particularly true of bacteria that cause diseases (pathogenic bacteria) and of beneficial bacteria that live in close association with larger hosts (symbiotic bacteria). Many of the essential tools that enable bacteria to exploit hosts are based on what can be called 'public goods'. These are enzymes or toxins and other compounds that bacteria must export outside the cell in order to break open host cells and harvest the resources. Bacteria also export chemical signals that communicate information about their abundance within hosts to other bacteria and may thereby coordinate attack. Efficient use of hosts therefore requires bacteria to act collectively, if a low proportion of bacteria fail to cooperate bacterial infections should to be less successful and produce fewer infections in new hosts. These public goods are expensive to make in terms of resources. In evolutionary terms cooperation can be unstable because bacteria may leave more offspring within hosts if they 'cheat' and fail to contribute to these expensive cooperative products. Evolutionary theory has made predictions about how cooperation could be maintained. If most infections are established by close relatives with similar strategies, metabolically expensive cooperation will benefit their relative and they, in turn will then spread the genes for cooperation. In addition, while competition within hosts can lead to selection for cheating, competition between groups of bacteria inhabiting different hosts will select for groups that exploit their host more efficiently, and which therefore cooperate. The evolutionary forces that can maintain cooperation between hosts and symbiotic bacteria are diverse. However, one possible mechanism is that host can discriminate between bacteria that are exploitative or not and produce increased immune responses against symbionts that are not cooperative. I propose to test these evolutionary ideas on cooperation, in relation to the production of toxins, antibiotics and chemical signals. Prelimary data also indicate that the exploitation of hosts by Bt is strongly affect by competition with symbionts such as P. agglomerans. I will test how competition with symbionts affects the expression of cooperative toxins. Conversely, these symbionts can cooperate with Bt rather than continue to cooperate with hosts as gut symbionts. I will test how host insects react to infections with 'cheating' symbionts. I will use a study system which is familiar to me and also of environmental and medical importance. This system is the insect-killing bacteria Baccillus thuringiensis, a caterpillar host (the larvae of the diamondback moth) and the gut symbiont Pantoea agglomerans. B. thuringiensis (Bt) is used as a biological pesticide. It is applied against pests in horticulture, forestry and fruit productionan and against mosquito larvae. It has an excellent safety record, it does not harm humans, animals or beneficial insect predators and is licensed as an organic spray. While Bt pesticides are efficient at killing pests they are relatively poor at being transmitted as a disease from pest to pest after spraying. Improved transmission would have many benefits for the ability of Bt to control pests. Preliminary data in my laboratory suggests that cooperative traits are vital for efficient transmission between hosts, as the above theory predicts. An understanding of how cooperation maintains efficient transmission and transmission maintains cooperation could therefore be vital to understanding how to improve its use. Bt is closely related to the bacteria that causes anthrax, Bacillus anthracis and to Bacillus cereus, several strains of which cause food-poisoning in humans. These human pathogens use very similar biochemical machinery to Bt and a understanding of how these bacteria cooperate to exploit hosts may eventually be of medical significance.

合作是细菌生活方式的共同特征。这对于引起疾病的细菌（致病菌）和与较大宿主密切相关的有益细菌（共生菌）可能尤其如此。许多使细菌能够利用宿主的基本工具都是基于所谓的“公共产品”。这些是酶或毒素和其他化合物，细菌必须将其输出到细胞外，以打破宿主细胞并收获资源。细菌还输出化学信号，将它们在宿主体内的丰度信息传达给其他细菌，从而可能协调攻击。因此，有效利用宿主需要细菌集体行动，如果低比例的细菌不能合作，细菌感染应该不太成功，在新宿主中产生较少的感染。就资源而言，这些公共产品的制造成本很高。从进化的角度来看，合作可能是不稳定的，因为如果细菌“作弊”，不能为这些昂贵的合作产品做出贡献，它们可能会在宿主体内留下更多的后代。进化论已经对如何维持合作做出了预测。如果大多数感染是由近亲用类似的策略建立的，那么代谢上昂贵的合作将使他们的亲戚受益，然后他们反过来会传播合作的基因。此外，虽然宿主内部的竞争可能导致选择欺骗，但栖息在不同宿主上的细菌群体之间的竞争将选择更有效地利用其宿主的群体，因此这些群体进行合作。能够维持宿主与共生细菌之间合作的进化力量是多种多样的。然而，一种可能的机制是宿主可以区分剥削性或非剥削性的细菌，并对不合作的共生体产生增强的免疫反应。我建议测试这些进化的想法合作，在生产毒素，抗生素和化学信号。实验数据还表明，Bt对宿主的利用受到与共生体（如成团拟单胞菌）竞争的强烈影响。我将测试与共生体的竞争如何影响合作毒素的表达。相反，这些共生体可以与Bt合作，而不是作为肠道共生体继续与宿主合作。我将测试宿主昆虫对“欺骗”共生体的感染有何反应。我将使用一个我熟悉的研究系统，该系统也具有环境和医学重要性。这个系统是杀虫细菌苏云金芽孢杆菌、毛虫宿主（小菜蛾幼虫）和肠道共生体成团泛菌。B。苏云金杆菌（Bt）是一种生物农药。它用于防治园艺、林业和水果生产中的害虫和蚊子幼虫。它具有良好的安全记录，它不会伤害人类，动物或有益的昆虫捕食者，并被许可作为有机喷雾剂。虽然Bt杀虫剂在杀死害虫方面是有效的，但它们在喷洒后作为一种疾病在害虫之间传播的能力相对较差。改善传播将对Bt控制害虫的能力有许多好处。正如上述理论所预测的那样，我实验室的初步数据表明，合作性状对于宿主之间的有效传播至关重要。因此，了解合作如何维持高效传输，而传输又如何维持合作，对于了解如何改进其使用至关重要。Bt与导致炭疽的细菌炭疽杆菌和蜡状芽孢杆菌密切相关，其中几种菌株会导致人类食物中毒。这些人类病原体使用与Bt非常相似的生化机制，了解这些细菌如何合作利用宿主可能最终具有医学意义。

项目成果

Environmental Impact of Genetically Modified Crops

• DOI: 10.1079/9781845934095.0000
• 发表时间: 2009-02
• 作者: N. Ferry;A. Gatehouse

Figure S2 from Shifts along parasite-mutualist continuum are opposed by fundamental trade-offs

图 S2 来自寄生互利连续体的转变受到基本权衡的反对

• DOI: 10.6084/m9.figshare.7862105
• 发表时间: 2019
• 作者: Matthews A

Figure S1 from Shifts along parasite-mutualist continuum are opposed by fundamental trade-offs

图 S1 来自寄生互利连续体的转变受到基本权衡的反对

• DOI: 10.6084/m9.figshare.7862102
• 发表时间: 2019
• 作者: Matthews A

Bacterial Cooperation Causes Systematic Errors in Pathogen Risk Assessment due to the Failure of the Independent Action Hypothesis.

• DOI: 10.1371/journal.ppat.1004775
• 发表时间: 2015-04
• 期刊: PLoS pathogens
• 影响因子: 6.7
• 作者: Cornforth DM;Matthews A;Brown SP;Raymond B
• 通讯作者: Raymond B

Figure S3 from Shifts along parasite-mutualist continuum are opposed by fundamental trade-offs

图 S3 来自寄生互利连续体的转变受到基本权衡的反对

• DOI: 10.6084/m9.figshare.7862096
• 发表时间: 2019
• 作者: Matthews A