The evolution of a conjugative plasmid and its ability to increase bacterial fitness
The evolution of a conjugative plasmid and its ability to increase bacterial fitness
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DOI：
10.1098/rsbl.2004.0275
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发表时间：
2005-06-22
期刊：
影响因子：
3.3
通讯作者：
Gordo, I
中科院分区：
文献类型：
--
作者：
Dionisio, F;Conceiçao, IC;Gordo, I
接合质粒是染色体外的DNA元件，能够水平传播，存在于许多天然分离的细菌中。虽然质粒可能携带有益基因到它们的细菌宿主，但它们也可能导致适应性成本。在这项工作中，我们研究了R1质粒的进化，我们发现，尽管R1质粒赋予其宿主一个初始成本，420代后，成本消失在所有五个独立的进化实验。事实上，在这五个实验中的两个中，进化出的接合质粒实际上赋予了宿主适应性优势。此外，携带进化质粒之一的祖先克隆的相对适合度显著高于无质粒的祖先细胞和携带进化质粒的进化细胞。考虑到R1质粒可以在不同种类的肠杆菌中传播，我们想知道进化的质粒在沙门氏菌细胞内会产生什么样的影响。我们发现，进化的质粒也能够显着增加这些细胞的相对适应性。我们的研究结果表明，即使停止抗生素的普遍使用，前几年用抗生素选择的接合质粒仍然可以在细菌种群中持续存在，甚至侵入新的菌株。
Conjugative plasmids are extra-chromosomal DNA elements that are capable of horizontal transmission and are found in many natural isolated bacteria. Although plasmids may carry beneficial genes to their bacterial host, they may also cause a fitness cost. In this work, we studied the evolution of the R1 plasmid and we found that, in spite of the R1 plasmid conferring an initial cost to its host, after 420 generations the cost disappeared in all five independent evolution experiments. In fact, in two of these five experiments evolved conjugative plasmids actually conferred a fitness advantage to their hosts. Furthermore, the relative fitness of the ancestral clone bearing one of the evolved plasmids is significantly higher than both the plasmid-free ancestral cells and the evolved cells carrying the evolved plasmid. Given that the R1 plasmid may spread among different species of enterobacteria, we wondered what the effect of the evolved plasmid would be inside Salmonella enterica cells. We found that the evolved plasmid is also able to dramatically increase the relative fitness of these cells. Our results suggest that even if general usage of antibiotics is halted, conjugative plasmids that have been selected with antibiotics in previous years can still persist among bacterial populations or even invade new strains.