PDF(Pubmed)
Abstract：
Free-living amoebae (FLA) are phagocytic protists that play crucial roles in microbial communities as significant microbial grazers. However, our current knowledge of their diversity, ecology, and population genetic structures is marginal due to the shallow and biased sampling of ecosystems and the use of few, poorly resolving molecular markers. Thirty-two FLA were isolated from soil and water samples collected across representative ecosystems of the State of Morelos in Central Mexico, including the drinking water distribution system (DWDS) from the state capital. We classified our isolates as members of Acanthamoeba, Vermamoeba, Naegleria, and Tetramitus by 18S ribosomal DNA (rDNA) sequencing. Vermamoeba isolates were recovered exclusively from the DWDS samples. In contrast, Naegleria strains displayed a broad distribution in soil and water samples across the natural ecosystems. We used a combination of phylogenetic and population genetic analyses of internal transcribed spacer (ITS) and cytochrome oxidase subunit I (COI) sequences from our isolates and a comprehensive set of reference sequences to analyze the currently known diversity of Naegleria spp. Significant associations were uncovered between the most prevalent lineages of Naegleria and Vermamoeba and broad ecological and geographical variables at regional and global levels. The population structure and cryptic diversity within the Naegleria galeacystis-Naegleria americana and Vermamoeba vermiformis species complexes were thoroughly analyzed. Our results prove that the genus Vermamoeba, which was previously thought to consist of only one species, actually encompasses at least seven widely distributed species, as indicated by consistent evidence from Bayesian phylogenetics, two species-delimitation programs, and population genetics analyses. IMPORTANCE Our study sheds new light on the population genetic structure of V. vermiformis and diverse Naegleria species. Using improved molecular markers and advanced analytical approaches, we discovered that N. americana, previously considered a single species, actually contains multiple distinct lineages, as revealed by COI sequencing. These lineages are highly differentiated, with little gene flow between them. Our findings demonstrate that the genus Vermamoeba holds multiple cryptic species, requiring a significant taxonomic revision in light of multilocus sequence analyses. These results advance our understanding of the ecology, molecular systematics, and biogeography of these genera and species complexes at both regional and global scales. This study has significant implications for diagnosing amoebal infections and evaluating health risks associated with FLA in domestic and recreational waters.
摘要：
自由生活的变形虫（FLA）是吞噬原生生物，在微生物群落中作为重要的微生物食草动物发挥着至关重要的作用。然而,我们目前对它们多样性的了解，生态学,和种群遗传结构是边缘的，由于浅层和有偏见的生态系统采样和使用很少，分辨率较差的分子标记。从墨西哥中部莫雷洛斯州代表性生态系统中收集的土壤和水样中分离出32个FLA，包括国家首都的饮用水分配系统（DWDS）。我们将我们的分离株归类为棘阿米巴的成员，Vermamoeba,Naegleria,和Tetramitus通过18S核糖体DNA（rDNA）测序。Vermamoeba分离株仅从DWDS样品中回收。相比之下,Naegleria菌株在自然生态系统的土壤和水样品中表现出广泛的分布。我们结合了分离株的内部转录间隔区（ITS）和细胞色素氧化酶亚基I（COI）序列的系统发育和种群遗传分析，以及一套全面的参考序列，以分析当前已知的Naegleriaspp的多样性。在区域和全球范围内，最普遍的Naegleria和Vermamoeba谱系与广泛的生态和地理变量之间发现了显着关联。彻底分析了Naegleriagaleacystis-Naegleriaamericana和Vermammaoebavermiformis物种复合物中的种群结构和隐性多样性。我们的结果证明Vermamoeba属，以前被认为只有一个物种，实际上包括至少七个分布广泛的物种，正如贝叶斯系统发育学的一致证据所表明的那样，两个物种划界方案，和群体遗传学分析。重要性我们的研究为Vermiformis和多种Naegleria物种的种群遗传结构提供了新的思路。使用改进的分子标记和先进的分析方法，我们发现了北美，以前被认为是单一物种，实际上包含多个不同的谱系，正如COI测序所揭示的那样。这些谱系是高度分化的，它们之间几乎没有基因流动。我们的发现表明，Vermamoeba属拥有多个隐蔽物种，根据多位点序列分析，需要进行重大的分类学修订。这些结果促进了我们对生态学的理解，分子系统学，以及这些属和物种复合体在区域和全球范围内的生物地理学。这项研究对诊断变形虫感染和评估家庭和休闲水域中与FLA相关的健康风险具有重要意义。
