Phase-Variable Control of Multiple Phenotypes in Acinetobacter baumannii Strain AB5075
Phase-Variable Control of Multiple Phenotypes in Acinetobacter baumannii Strain AB5075
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DOI：
10.1128/jb.00188-15
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发表时间：
2015-08-01
影响因子：
3.2
通讯作者：
Rather, Philip N.
中科院分区：
文献类型：
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作者：
Tipton, Kyle A.;Dimitrova, Daniela;Rather, Philip N.
鲍曼不动杆菌菌株AB 5075产生具有两种不透明表型的菌落，称为不透明和半透明。这些表型是不稳定的，并且观察到不透明和半透明的菌落变体以高频率相互转化，这表明相变量机制是负责的。菌落内和肉汤培养物中的相位变化的频率以细胞密度依赖性的方式增加，并且由细胞外因子的积累介导。该因子与已知的A.鲍曼不动杆菌信号分子3-OH C-12-高丝氨酸内酯。不透明和半透明的菌落变体表现出许多表型差异，包括细胞形态，表面运动性，生物膜形成，抗生素耐药性和大蜡螟模型中的毒力。其他临床分离株表现出类似的相变量控制菌落混浊，这表明这可能是一个共同的特点。重要的是，在鲍曼不动杆菌中已经鉴定了导致不透明和半透明菌落表型之间相互转化的新的相位可变机制。这种相位变化还协调调节运动性、细胞形状、生物膜形成、抗生素抗性和毒力。在高细胞密度下，通过可扩散的细胞外信号，相位变化的频率增加。据我们所知，这份报告提出了第一个例子，相位变化的A。鲍曼不动杆菌，也是细菌中群体感应介导的相变化控制的第一个例子。这一发现很重要，因为这种相位可变机制只能通过使用斜射光改变菌落不透明度来识别;鲍曼不动杆菌可能在不知不觉中与不同的菌落变体一起工作。
Acinetobacter baumannii strain AB5075 produces colonies with two opacity phenotypes, designated opaque and translucent. These phenotypes were unstable and opaque and translucent colony variants were observed to interconvert at high frequency, suggesting that a phase-variable mechanism was responsible. The frequency of phase variation both within colonies and in broth cultures increased in a cell density-dependent manner and was mediated by the accumulation of an extracellular factor. This factor was distinct from the known A. baumannii signaling molecule 3-OH C-12-homoserine lactone. Opaque and translucent colony variants exhibited a number of phenotypic differences, including cell morphology, surface motility, biofilm formation, antibiotic resistance, and virulence in a Galleria mellonella model. Additional clinical isolates exhibited a similar phase-variable control of colony opacity, suggesting that this may be a common feature of A. baumannii.IMPORTANCEA novel phase-variable mechanism has been identified in Acinetobacter baumannii that results in an interconversion between opaque and translucent colony phenotypes. This phase variation also coordinately regulates motility, cell shape, biofilm formation, antibiotic resistance, and virulence. The frequency of phase variation is increased at high cell density via a diffusible extracellular signal. To our knowledge, this report presents the first example of phase variation in A. baumannii and also the first example of quorum sensing-mediated control of phase variation in a bacterium. The findings are important, as this phase-variable mechanism can be identified only via changes in colony opacity using oblique light; therefore, many researchers studying A. baumannii may unknowingly be working with different colony variants.