Laboratorio de Evolución Molecular y Experimental, Instituto de Ecología, Universidad Nacional Autónoma de México, Mexico City, Mexico.
Environ Microbiol. 2012 Sep;14(9):2323-33. doi: 10.1111/j.1462-2920.2012.02784.x. Epub 2012 May 29.
The evolutionary history and ecological differentiation of the genus Exiguobacterium was characterized within natural communities from the Cuatro Cienegas Basin, Mexico. Exiguobacterium comprises both halophilic and alkaliphilic bacteria that are abundant among the aquatic systems of the Cuatro Cienegas Basin. We obtained complete sequences of the 16srRNA gene and partial sequences of four housekeeping genes (citC, rpoB, recA and hsp70) in 183 Exiguobacterium isolates retrieved from distinct aquatic systems. We defined three main phylogroups that are closely related to marine and thermophilic species of the genus. These phylogroups were neither specific to a given aquatic system nor to a particular salinity. Phylogenetic reconstruction indicated the presence of several small clusters within the phylogroups. These clusters consisted of isolates predominantly retrieved from sediment or water. Unifrac and AdaptML analyses confirmed this observation, pointing towards a clear pattern of differentiation linked to either sediment or water habitats. Our results are in line with the concept that niche differentiation is one of the main factors shaping prokaryotic populations and leading to evolutionary divergence.
我们从墨西哥四泉谷盆地的自然群落中研究了极端短小杆菌属的进化历史和生态分化。极端短小杆菌属包括嗜盐菌和嗜堿菌，它们在四泉谷盆地的水生系统中大量存在。我们从不同的水生系统中获得了 183 株极端短小杆菌属的 16srRNA 基因全序列和 4 个看家基因（citC、rpoB、recA 和 hsp70）的部分序列。我们定义了三个主要的系统发育群，它们与该属的海洋和嗜热物种密切相关。这些系统发育群既不是特定于特定的水生系统，也不是特定于特定的盐度。系统发育重建表明，在系统发育群中存在几个小簇。这些簇主要由沉积物或水中的分离株组成。UniFrac 和 AdaptML 分析证实了这一观察结果，表明存在与沉积物或水栖息地明显相关的分化模式。我们的结果与这样的概念一致，即生态位分化是塑造原核生物种群并导致进化分歧的主要因素之一。
