Interspecific competition and siderophore-mediated cooperation in Pseudomonas aeruginosa
Interspecific competition and siderophore-mediated cooperation in Pseudomonas aeruginosa
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DOI：
10.1038/ismej.2007.96
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发表时间：
2008-01-01
期刊：
影响因子：
11
通讯作者：
Buckling, Angus
中科院分区：
文献类型：
--
作者：
Harrison, Freya;Paul, Jon;Buckling, Angus
微生物之间的种内和种间相互作用可能在确定微生物感染的严重性方面发挥重要作用。在这里，我们研究了共同感染的条件致病菌金黄色葡萄球菌和铜绿假单胞菌之间的相互作用对铜绿假单胞菌社会特征的表型和遗传变化的影响，铁清除铁载体的产生。铁载体在铁限制的反应中被上调，并在确定微生物感染的毒力方面发挥关键作用。铁载体的生产对个体生产者来说在代谢上是昂贵的，但对整个群体有利，因为铁载体可以被铁载体受体附近的所有细胞使用。因此，铁载体生产者的种群可能会被非生产性的骗子入侵。以前的研究表明，铜绿假单胞菌可以裂解S。金黄色葡萄球菌，提供游离铁的来源。因此，我们假设S.金黄色葡萄球菌可能导致铁载体产生的兼性下调，并进而减少对铁载体欺骗的选择。我们通过在存在和不存在游离铁和S.金黄色葡萄球菌，在一个完全析因设计。铁有预期的效果：铁载体的产生被下调，作弊者进化不那么容易，但是S。金黄色葡萄球菌反而增加了兼性铁载体的产生和对欺骗的选择。这可能是因为S。金黄色葡萄球菌具有竞争铁的净效应，而不是充当铁源。这项研究表明，种间竞争可以有一个显着的影响种内的社会相互作用。
Both intra- and interspecific interactions between microbes are likely to play an important role in determining the severity of microbial infections. Here, we study the impact of interactions between coinfecting opportunistic pathogens Staphylococcus aureus and Pseudomonas aeruginosa on both phenotypic and genetic changes in a P. aeruginosa social trait, the production of iron-scavenging siderophores. Siderophores are facultatively upregulated in response to iron limitation and play a key role in determining the virulence of microbial infections. Siderophore production is metabolically expensive to individual producers but benefits the group as a whole because siderophores can be used by all cells in the vicinity with siderophore receptors. Hence, populations of siderophore producers can be invaded by nonproducing cheats. Previous work has shown that P. aeruginosa can lyse S. aureus, supplying a source of free iron. We therefore hypothesized that the presence of S. aureus might result in facultative downregulation of siderophore production, and in turn, reduced selection for siderophore cheats. We tested this hypothesis by evolving P. aeruginosa in the presence and absence of free iron and S. aureus, in a fully factorial design. Iron had the expected effect: siderophore production was downregulated and cheats evolved less readily, but the presence of S. aureus instead increased facultative siderophore production and selection for cheats. This is probably because the S. aureus had the net effect of competing for iron, rather than acting as an iron source. This study demonstrates that interspecific competition can have a marked effect on intraspecific social interactions.