Centre Armand-Frappier Santé Biotechnologie, Institut National de la Recherche Scientifique (INRS), Laval, Québec, Canada.
mSphere. 2023 Apr 20;8(2):e0005723. doi: 10.1128/msphere.00057-23. Epub 2023 Feb 28.
The ability to generate a subpopulation of small colony variants (SCVs) is a conserved feature of Pseudomonas aeruginosa and could represent a key adaptive strategy to colonize and persist in multiple niches. However, very little is known about the role of the SCV phenotype, the conditions that promote its emergence, and its possible involvement in an adaptive strategy. In the present work, we investigated the selective conditions promoting the emergence of SCVs from the prototypical strain PA14, which readily forms SCVs in nonagitated standing cultures. We found that O limitation, which causes a redox imbalance, is the main factor selecting for the SCV phenotype, which promotes survival of the population formation of a biofilm at the air-liquid interface to access the electron acceptor. When this selective pressure is relieved by aeration or supplementation of an alternative electron acceptor, SCVs are barely detectable. We also observed that SCV emergence contributes to redox rebalancing, suggesting that it is involved in an adaptive strategy. We conclude that selection for the SCV phenotype is an adaptive solution adopted by P. aeruginosa to access poorly available O. The bacterium Pseudomonas aeruginosa is an opportunistic pathogen that thrives in many environments. It poses a significant health concern, notably because it is a causative agent of nosocomial infections and the most prevalent pathogen found in the lungs of people with cystic fibrosis. In infected hosts, its persistence is often related to the emergence of an alternative phenotype known as small colony variant (SCV). Identification of conditions selecting for the SCV phenotype contributes to knowledge regarding adaptive mechanisms exploited by P. aeruginosa to survive in multiple niches and persist during infections. Hindering this adaptation strategy could help control persistent P. aeruginosa infections.
能够产生小菌落变种 (SCV) 亚群是铜绿假单胞菌的保守特征，可能代表了定植和在多个小生境中持续存在的关键适应策略。然而，对于 SCV 表型的作用、促进其出现的条件以及其在适应策略中的可能参与，人们知之甚少。在本工作中，我们研究了促进原型菌株 PA14 中 SCV 出现的选择性条件，该菌株在非搅拌静置培养中很容易形成 SCV。我们发现，氧化还原失衡导致的 O 限制是选择 SCV 表型的主要因素，这促进了种群的存活和生物膜的形成，以便在气液界面处获得电子受体。当通过通气或补充替代电子受体来缓解这种选择压力时，几乎无法检测到 SCV。我们还观察到 SCV 的出现有助于氧化还原再平衡，表明它参与了一种适应策略。我们得出结论，选择 SCV 表型是铜绿假单胞菌采用的一种适应性解决方案，以获取难以获得的 O。 铜绿假单胞菌是一种机会性病原体，在许多环境中都能茁壮成长。它是一个重大的健康问题，特别是因为它是医院获得性感染的病原体，也是囊性纤维化患者肺部最常见的病原体。在受感染的宿主中，其持续存在通常与另一种表型的出现有关，称为小菌落变种 (SCV)。确定选择 SCV 表型的条件有助于了解铜绿假单胞菌在多个小生境中生存和在感染过程中持续存在所利用的适应机制。阻碍这种适应策略可能有助于控制持续性铜绿假单胞菌感染。
