Evolutionary adaptation of bacteria to nonantibiotic selective forces, such as osmotic stress, has been previously associated with increased antibiotic resistance, but much less is known about potentially sensitizing effects of nonantibiotic stressors. In this study, we use laboratory evolution to investigate adaptation of Enterococcus faecalis, an opportunistic bacterial pathogen, to a broad collection of environmental agents, ranging from antibiotics and biocides to extreme pH and osmotic stress. We find that nonantibiotic selection frequently leads to increased sensitivity to other conditions, including multiple antibiotics. Using population sequencing and whole-genome sequencing of single isolates from the evolved populations, we identify multiple mutations in genes previously linked with resistance to the selecting conditions, including genes corresponding to known drug targets or multidrug efflux systems previously tied to collateral sensitivity. Finally, we hypothesized based on the measured sensitivity profiles that sequential rounds of antibiotic and nonantibiotic selection may lead to hypersensitive populations by harnessing the orthogonal collateral effects of particular pairs of selective forces. To test this hypothesis, we show experimentally that populations evolved to a sequence of linezolid (an oxazolidinone antibiotic) and sodium benzoate (a common preservative) exhibit increased sensitivity to more stressors than adaptation to either condition alone. The results demonstrate how sequential adaptation to drug and nondrug environments can be used to sensitize bacteria to antibiotics and highlight new potential strategies for exploiting shared constraints governing adaptation to diverse environmental challenges.

中文翻译：

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利用非抗生素应激源的选择使细菌对抗生素敏感。

细菌对非抗生素选择力（例如渗透压）的进化适应以前被认为与抗生素耐药性增加有关，但对非抗生素应激源的潜在致敏作用知之甚少。在这项研究中，我们利用实验室进化来研究粪肠球菌（一种机会性细菌病原体）对一系列环境因素的适应，从抗生素和杀菌剂到极端 pH 值和渗透压。我们发现非抗生素选择经常导致对其他病症（包括多种抗生素）的敏感性增加。使用来自进化群体的单个分离株的群体测序和全基因组测序，我们鉴定了先前与选择条件抗性相关的基因中的多个突变，包括与先前与附带敏感性相关的已知药物靶标或多药物外排系统相对应的基因。最后，我们根据测量的敏感性曲线假设，通过利用特定选择力对的正交附带效应，连续轮次的抗生素和非抗生素选择可能会导致过敏群体。为了检验这一假设，我们通过实验证明，进化到一系列利奈唑胺（一种恶唑烷酮抗生素）和苯甲酸钠（一种常见防腐剂）的群体比单独适应任何一种条件表现出对更多压力源的敏感性更高。结果证明了如何利用对药物和非药物环境的连续适应来使细菌对抗生素敏感，并强调如何利用共同的约束来适应不同的环境挑战。