Interactions of the microbial mat community with the sedimentary environment were evaluated in two shallow, ephemeral lakes with markedly different hydrochemistry and mineralogy. The characterization of growing and decaying microbial mats by light microscopy observations and fluorescence in situ hybridization was complemented with biogeochemical and mineralogical measurements. The lakes studied were Eras and Altillo Chica, both located in Central Spain and representing poly-extreme environments. Lake Eras is a highly alkaline, brackish to saline lake containing a high concentration of chloride, and in which the carbonate concentration exceeds the sulfate concentration. The presence of magnesium is crucial for the precipitation of hydromagnesite in microbialites of this lake. Altillo Chica is a mesosaline to hypersaline playa lake with high concentrations of sulfate and chloride, favoring the formation of gypsum microbialites. Differences in the microbial community composition and mineralogy of the microbialites between the two lakes were primarily controlled by alkalinity and salinity. Lake Eras was dominated by the cyanobacterial genus Oscillatoria, as well as Alphaproteobacteria, Gammaproteobacteria and Firmicutes. When the mat decayed, Alphaproteobacteria and Deltaproteobacteria increased and became the dominant heterotrophs, as opposed to Firmicutes. In contrast, Deltaproteobacteria was the most abundant group in Lake Altillo Chica, where desiccation led to mats decay during evaporite formation. In addition to Deltaproteobacteria, Cyanobacteria, Actinobacteria, Alphaproteobacteria and Gammaproteobacteria were found in Altillo Chica, mostly during microbial mats growth. At both sites, microbial mats favored the precipitation of sulfate and carbonate minerals. The precipitation of carbonate is higher in the soda lake due to a stronger alkalinity engine and probably a higher degradation rate of exopolymeric substances. Our findings clarify the distribution patterns of microbial community composition in ephemeral lakes at the levels of whole communities, which were subjected to environmental conditions similar to those that may have existed during early Earth.

中文翻译：

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碱性和高盐度沉积环境中干湿循环条件下微生物垫中矿物形成的季节变化

在两个水化学和矿物学明显不同的短暂浅湖中，评估了微生物垫群落与沉积环境的相互作用。通过光学显微镜观察和荧光原位杂交来表征生长中的微生物席和衰变的微生物席，并辅以生物地球化学和矿物学测量。研究的湖泊是Eras和Altillo Chica，它们都位于西班牙中部，代表着极端的极端环境。埃拉斯湖是一种高度碱性的咸淡盐湖，盐湖中的氯化物浓度很高，碳酸盐浓度超过硫酸盐浓度。镁的存在对于该菱镁矿中水菱镁矿的沉淀至关重要。Altillo Chica是中盐湖到盐湖过盐湖，含有高浓度的硫酸盐和氯化物，有利于形成石膏微辉石。两个湖泊之间的微生物群落组成和微生物组成的矿物学差异主要受碱度和盐度控制。时代湖由蓝细菌属主导颤藻，以及Alphaproteobacteria，Gammaproteobacteria和Firmicutes。当垫子腐烂时，阿尔法变形菌和德尔氏变形菌增加，成为主要的异养菌，而不是硬毛菌。相反，Deltaproteobacteria细菌是Altillo Chica湖中数量最多的一组，那里的干燥导致蒸发层形成过程中垫层的腐烂。除三角洲细菌外，在Altillo Chica中还发现了蓝细菌，放线菌，丙酸杆菌和丙酸杆菌，主要是在微生物垫生长期间。在两个地点，微生物垫都有利于硫酸盐和碳酸盐矿物的沉淀。苏打湖中碳酸盐的沉淀较高，这归因于较强的碱度引擎以及外聚合物质的降解速率较高。