Abstract：
Andean wetlands hold extremophilic communities adapted to live in harsh conditions. Here, we investigated the microbial ecology of three high-altitude hypersaline ponds from La Puna region (Argentina) showing an increasing extent of desiccation by analyzing their lipid sedimentary record. We recreated the microbial community structure and the carbon metabolisms in each lacustrine system based on the molecular distribution of lipid biomarkers and their compound-specific carbon and hydrogen isotopic signatures. We detected lipid compounds considered to be biomarkers of cyanobacteria, sulfate-reducing bacteria, purple sulfur bacteria, and archaea in the three Andean ponds, as well as diatoms in the intermediate salinity system. The relative abundance of purple sulfur and sulfate-reducing bacteria decreased with salinity, whereas cyanobacteria and archaea decreased their relative abundance in the mid-saline pond to increase it again and became both prevailing at the highest salinity. Carbon fixation in the three ponds was driven by a combination of the reductive tricarboxylic acid cycle, the reductive pentose phosphate cycle, and the reductive acetyl-CoA pathway. This work is the first to describe molecular and isotopic lipid fingerprints in wetlands from the central Andean Puna, and serves as a basis for further biogeochemical studies in the area.
摘要：
安第斯湿地拥有适合在恶劣条件下生活的极端社区。这里,我们调查了来自LaPuna地区（阿根廷）的三个高海拔高盐池塘的微生物生态学，通过分析其脂质沉积记录显示出干燥程度的增加。我们根据脂质生物标志物的分子分布及其化合物特异性碳和氢同位素特征，重建了每个湖相系统中的微生物群落结构和碳代谢。我们检测到被认为是蓝细菌生物标志物的脂质化合物，硫酸盐还原细菌，紫色硫细菌，和三个安第斯池塘中的古细菌，以及中间盐度系统中的硅藻。紫色硫和硫酸盐还原菌的相对丰度随盐度而降低，而蓝细菌和古细菌在中盐水池塘中的相对丰度降低，以再次增加，并在最高盐度时盛行。三个池塘中的碳固定是由还原性三羧酸循环的组合驱动的，还原性磷酸戊糖循环，和还原性乙酰辅酶A途径。这项工作是第一个描述来自安第斯Puna中部湿地的分子和同位素脂质指纹图谱，并作为该地区进一步生物地球化学研究的基础。
