University of Manchester, Faculty of Life Sciences, Oxford Road, Manchester, UK.
ISME J. 2013 Apr;7(4):791-9. doi: 10.1038/ismej.2012.170. Epub 2013 Jan 10.
The naturally transformable bacterium Streptococcus pneumoniae is able to take up extracellular DNA and incorporate it into its genome. Maintaining natural transformation within a species requires that the benefits of transformation outweigh its costs. Although much is known about the distribution of natural transformation among bacterial species, little is known about the degree to which transformation frequencies vary within species. Here we find that there is significant variation in transformation frequency between strains of Streptococcus pneumoniae isolated from asymptomatic carriage, and that this variation is not concordant with isolate genetic relatedness. Polymorphism in the signalling system regulating competence is also not causally related to differences in transformation frequency, although this polymorphism does influence the degree of genetic admixture experienced by bacterial strains. These data suggest that bacteria can evolve new transformation frequencies over short evolutionary timescales. This facility may permit cells to balance the potential costs and benefits of transformation by regulating transformation frequency in response to environmental conditions.
可自然转化的肺炎链球菌能够摄取细胞外 DNA 并将其整合到基因组中。在一个物种内维持自然转化需要转化的益处超过其成本。尽管人们对细菌物种之间自然转化的分布有了很多了解，但对于物种内转化频率的变化程度知之甚少。在这里，我们发现从无症状携带中分离出的肺炎链球菌菌株之间的转化频率存在显著差异，而且这种差异与分离株遗传相关性不一致。调节感受态的信号系统的多态性也与转化频率的差异没有因果关系，尽管这种多态性确实会影响细菌菌株经历的遗传混合程度。这些数据表明，细菌可以在短时间内进化出新的转化频率。这种能力可以使细胞通过响应环境条件调节转化频率来平衡转化的潜在成本和益处。
