Diaz Kelly E, Remold Susanna K, Onyiri Ogochukwu, Bozeman Maura, Raymond Peter A, Turner Paul E
Department of Ecology & Evolutionary Biology, Yale University, New Haven, CT, United States.
Department of Biology, University of Louisville, Louisville, KY, United States.
Front Microbiol. 2018 Feb 27;9:305. doi: 10.3389/fmicb.2018.00305. eCollection 2018.
is an opportunistic pathogen of particular concern to immune-compromised people, such as cystic fibrosis patients and burn victims. These bacteria grow in built environments including hospitals and households, and in natural environments such as rivers and estuaries. However, there is conflicting evidence whether recent environments like the human lung and open ocean affect growth performance in alternate environments. We hypothesized that bacteria recently isolated from dissimilar habitats should grow differently in media containing artificial versus natural resources. To test this idea, we examined growth of isolates from three environments (estuary, household, and clinic) in three media types: minimal-glucose lab medium, and media prepared from sugar maple leaves or big bluestem grass. We used automated spectrophotometry to measure high-resolution growth curves for all isolate by media combinations, and studied two fitness parameters: growth rate and maximum population density. Results showed high variability in growth rate among isolates, both overall and in its dependence on assay media, but this variability was not associated with habitat of isolation. In contrast, total growth (change in absorbance over the experiment) differed overall among habitats of isolation, and there were media-specific differences in mean total growth among habitats of isolation, and in among-habitat variability in the media-specific response. This was driven primarily by greater total growth of estuary isolates when compared with those from other habitats of origin, and greater media-specific variability among household isolates than those from other habitats of origin. Taken together, these results suggest that for growth rate bacteria appear to be broad generalists without regard to current or recent habitat, whereas for total growth a signature of recent ecological history can be detected.
是一种对免疫功能低下的人群（如囊性纤维化患者和烧伤患者）特别值得关注的机会致病菌。这些细菌在包括医院和家庭在内的建筑环境中生长，也在河流和河口等自然环境中生长。然而，关于人类肺部和开阔海洋等近期环境是否会影响其在其他环境中的生长性能，存在相互矛盾的证据。我们假设，最近从不同栖息地分离出的细菌在含有人工资源与自然资源的培养基中生长情况会有所不同。为了验证这一想法，我们检测了来自三种环境（河口、家庭和诊所）的菌株在三种培养基类型中的生长情况：最低葡萄糖实验室培养基，以及用糖枫叶或大须芒草制备的培养基。我们使用自动分光光度法测量所有菌株在不同培养基组合下的高分辨率生长曲线，并研究了两个适合度参数：生长速率和最大种群密度。结果表明，菌株之间的生长速率总体上以及在对检测培养基的依赖性方面都存在很大差异，但这种差异与分离栖息地无关。相比之下，总生长量（实验过程中吸光度的变化）在不同分离栖息地之间总体上存在差异，不同分离栖息地之间在平均总生长量以及培养基特异性反应中的栖息地间变异性方面也存在培养基特异性差异。这主要是由于与其他来源栖息地的菌株相比，河口分离株的总生长量更大，以及家庭分离株在培养基特异性方面的变异性比其他来源栖息地的菌株更大。综上所述，这些结果表明，就生长速率而言，细菌似乎是广泛的通才，与当前或近期的栖息地无关，而对于总生长量，可以检测到近期生态历史的特征。
