英国威康桑格研究所Trevor D. Lawley和Nitin Kumar等研究人员合作发现艰难梭状芽胞杆菌（Clostridium difficile）物种形成过程中对宿主传播周期的适应。这一研究成果于2019年9月发表在国际学术期刊《自然—遗传学》上。

研究人员发现，一种能够形成孢子并且与医疗卫生相关的肠道病原体——艰难梭状芽胞杆菌正在主动地进行物种形成。通过对906株菌的大规模基因组分析，研究人员证明正在进行的物种形成过程与新形成物种中核心基因的正选择有关，这些基因参与孢子形成和简单膳食糖的代谢。功能验证表明，当葡萄糖或果糖可用于代谢时，新的艰难梭状芽胞杆菌产生更具抗性并具有增加的孢子形成和宿主定殖能力的孢子。因此，研究人员发现了一种新兴的艰难梭状芽胞杆菌物种的形成，其选择代谢简单的膳食糖并产生高抗性的孢子，从而有利于在医疗中的传播。

研究人员表示，细菌物种形成是一个基本的进化过程，其特征是基因型和表型特征不同。然而，影响遗传适应的选择压力以及它们如何与支撑新细菌物种形成的生物学变化相关仍然知之甚少。

附：英文原文

Title: Adaptation of host transmission cycle during Clostridium difficile speciation

Author: Nitin Kumar, Hilary P. Browne, Elisa Viciani, Samuel C. Forster, Simon Clare, Katherine Harcourt, Mark D. Stares, Gordon Dougan, Derek J. Fairley, Paul Roberts, Munir Pirmohamed, Martha R. J. Clokie, Mie Birgitte Frid Jensen, Katherine R. Hargreaves, Margaret Ip, Lothar H. Wieler, Christian Seyboldt, Torbjrn Norn, Thomas V. Riley, Ed J. Kuijper, Brendan W. Wren, Trevor D. Lawley

Issue&Volume: Volume 51 Issue 9

Abstract: Bacterial speciation is a fundamental evolutionary process characterized by diverging genotypic and phenotypic properties. However, the selective forces that affect genetic adaptations and how they relate to the biological changes that underpin the formation of a new bacterial species remain poorly understood. Here, we show that the spore-forming, healthcare-associated enteropathogen Clostridium difficile is actively undergoing speciation. Through large-scale genomic analysis of 906 strains, we demonstrate that the ongoing speciation process is linked to positive selection on core genes in the newly forming species that are involved in sporulation and the metabolism of simple dietary sugars. Functional validation shows that the new C. difficile produces spores that are more resistant and have increased sporulation and host colonization capacity when glucose or fructose is available for metabolism. Thus, we report the formation of an emerging C. difficile species, selected for metabolizing simple dietary sugars and producing high levels of resistant spores, that is adapted for healthcare-mediated transmission.

DOI: 10.1038/s41588-019-0478-8

Source:https://www.nature.com/articles/s41588-019-0478-8