Microbial mats are biologically diverse communities that are analogs to some of the earliest ecosystems on Earth. In this study, we describe a unique transiently hypersaline microbial mat uncovered in a shallow pond within the Cuatro Cienegas Basin (CCB) in northern México. The CCB is an endemism-rich site that harbors living stromatolites that have been studied to understand the conditions of the Precambrian Earth. These microbial mats form elastic domes filled with biogenic gas, and the mats have a relatively large and stable subpopulation of archaea. For this reason, this site has been termed archaean domes (AD). The AD microbial community was analyzed by metagenomics over three seasons. The mat exhibited a highly diverse prokaryotic community dominated by bacteria. Bacterial sequences are represented in 37 phyla, mainly Proteobacteria, Firmicutes, and Actinobacteria, that together comprised >50% of the sequences from the mat. Archaea represented up to 5% of the retrieved sequences, with up to 230 different archaeal species that belong to 5 phyla (Euryarchaeota, Crenarchaeota, Thaumarchaeota, Korarchaeota, and Nanoarchaeota). The archaeal taxa showed low variation despite fluctuations in water and nutrient availability. In addition, predicted functions highlight stress responses to extreme conditions present in the AD, including salinity, pH, and water/drought fluctuation. The observed complexity of the AD mat thriving in high pH and fluctuating water and salt conditions within the CCB provides an extant model of great value for evolutionary studies, as well as a suitable analog to the early Earth and Mars.

中文翻译：

---

墨西哥夸特罗谢内加斯盆地的短暂高盐微生物垫孕育着多样化且稳定的古菌群落。

微生物垫是生物多样性的群落，类似于地球上一些最早的生态系统。在这项研究中，我们描述了在墨西哥北部 Cuatro Cienegas 盆地 (CCB) 内的一个浅池塘中发现的一种独特的瞬时高盐微生物垫。CCB 是一个富含特有物种的地点，蕴藏着活的叠层石，人们对这些叠层石进行了研究，以了解前寒武纪地球的状况。这些微生物垫形成充满生物气体的弹性圆顶，并且微生物垫具有相对较大且稳定的古细菌亚群。因此，该遗址被称为太古圆顶（AD）。通过宏基因组学对三个季节的 AD 微生物群落进行了分析。该垫展示了以细菌为主的高度多样化的原核生物群落。细菌序列存在于 37 个门中，主要是变形菌门、厚壁菌门和放线菌门，它们合计占垫子序列的 50% 以上。古菌占检索到的序列的 5%，有多达 230 种不同的古菌物种，属于 5 个门（广古菌门、Crenarchaeota、Thaumarchaeota、Korarchaeota 和 Nanoarchaeota）。尽管水和养分可用性存在波动，但古菌类群表现出较低的变异。此外，预测函数强调了 AD 中对极端条件的应激反应，包括盐度、pH 值和水/干旱波动。观察到的 AD 垫的复杂性在 CCB 内的高 pH 值和波动的水和盐条件下蓬勃发展，为进化研究提供了一个具有重要价值的现有模型，以及对早期地球和火星的合适模拟。