Global Health Institute, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.
FEMS Microbiol Rev. 2013 May;37(3):336-63. doi: 10.1111/j.1574-6976.2012.00353.x. Epub 2012 Sep 20.
Bacterial genomics is flourishing, as whole-genome sequencing has become affordable, readily available and rapid. As a result, it has become clear how frequently horizontal gene transfer (HGT) occurs in bacteria. The potential implications are highly significant because HGT contributes to several processes, including the spread of antibiotic-resistance cassettes, the distribution of toxin-encoding phages and the transfer of pathogenicity islands. Three modes of HGT are recognized in bacteria: conjugation, transduction and natural transformation. In contrast to the first two mechanisms, natural competence for transformation does not rely on mobile genetic elements but is driven solely by a developmental programme in the acceptor bacterium. Once the bacterium becomes competent, it is able to take up DNA from the environment and to incorporate the newly acquired DNA into its own chromosome. The initiation and duration of competence differ significantly among bacteria. In this review, we outline the latest data on representative naturally transformable Gram-negative bacteria and how their competence windows differ. We also summarize how environmental cues contribute to the initiation of competence in a subset of naturally transformable Gram-negative bacteria and how the complexity of the niche might dictate the fine-tuning of the competence window.
细菌基因组学正在蓬勃发展，因为全基因组测序变得经济实惠、易于获取且快速。因此，细菌中水平基因转移 (HGT) 的发生频率变得清晰可见。这一现象具有非常重要的潜在影响，因为 HGT 促进了多种过程，包括抗生素抗性盒的传播、编码毒素的噬菌体的分布以及致病性岛的转移。在细菌中，识别出三种 HGT 模式：接合、转导和自然转化。与前两种机制不同，自然转化能力不依赖于移动遗传元件，而是完全由受体细菌中的发育程序驱动。一旦细菌变得有能力，它就能够从环境中摄取 DNA，并将新获得的 DNA整合到自己的染色体中。不同细菌的转化能力的起始和持续时间有显著差异。在这篇综述中，我们概述了具有代表性的天然可转化革兰氏阴性细菌的最新数据，以及它们的转化窗如何不同。我们还总结了环境线索如何促进一部分天然可转化革兰氏阴性细菌的转化能力的起始，以及生态位的复杂性如何决定转化窗的微调。
