Laboratorio de Investigaciones Microbiológicas de Lagunas Andinas (LIMLA), Planta Piloto de Procesos Industriales Microbiológicos (PROIMI), CCT, CONICET, San Miguel de Tucumán, Tucumán, Argentina.
Department of Biogeochemistry, Max Planck Institute for Marine Microbiology, Celsiusstrasse 1, 28359, Bremen, Germany.
Microb Ecol. 2021 May;81(4):941-953. doi: 10.1007/s00248-020-01673-9. Epub 2021 Jan 2.
Arsenic (As) is a metalloid present in the earth's crust and widely distributed in the environment. Due to its high concentrations in the Andean valleys and its chemical similarity with phosphorus (P), its biological role in Andean Microbial Ecosystems (AMEs) has begun to be studied. The AMEs are home to extremophilic microbial communities that form microbial mats, evaporites, and microbialites inhabiting Andean lakes, puquios, or salt flats. In this work, we characterize the biological role of As and the effect of phosphate in AMEs from the Laguna Tebenquiche (Atacama Desert, Chile). Using micro X-ray fluorescence, the distribution of As in microbial mat samples was mapped. Taxonomic and inferred functional profiles were obtained from enriched cultures of microbial mats incubated under As stress and different phosphate conditions. Additionally, representative microorganisms highly resistant to As and able to grow under low phosphate concentration were isolated and studied physiologically. Finally, the genomes of the isolated Salicola sp. and Halorubrum sp. were sequenced to analyze genes related to both phosphate metabolism and As resistance. The results revealed As as a key component of the microbial mat ecosystem: (i) As was distributed across all sections of the microbial mat and represented a significant weight percentage of the mat (0.17 %) in comparison with P (0.40%); (ii) Low phosphate concentration drastically changed the microbial community in microbial mat samples incubated under high salinity and high As concentrations; (iii) Archaea and Bacteria isolated from the microbial mat were highly resistant to arsenate (up to 500 mM), even under low phosphate concentration; (iv) The genomes of the two isolates were predicted to contain key genes in As metabolism (aioAB and arsC/acr3) and the genes predicted to encode the phosphate-specific transport operon (pstSCAB-phoU) are next to the arsC gene, suggesting a functional relationship between these two elements.
砷（As）是地壳中存在的一种类金属，广泛分布于环境中。由于其在安第斯山谷中的高浓度以及与磷（P）的化学相似性，其在安第斯微生物生态系统（AMEs）中的生物作用开始受到研究。AMEs 是极端微生物群落的家园，这些微生物形成微生物垫、蒸发盐和微生物岩，栖息在安第斯湖泊、puquios 或盐滩中。在这项工作中，我们描述了 Laguna Tebenquiche（智利阿塔卡马沙漠）中 AMEs 中的 As 的生物作用以及磷酸盐的影响。使用微 X 射线荧光，对微生物垫样品中的 As 分布进行了映射。通过在 As 胁迫和不同磷酸盐条件下培养微生物垫的富集培养物，获得了分类和推断功能的图谱。此外，还分离并从生理上研究了对 As 高度耐受且能够在低磷酸盐浓度下生长的代表性微生物。最后，对分离的 Salicola sp.和 Halorubrum sp.的基因组进行了测序，以分析与磷酸盐代谢和 As 抗性相关的基因。结果表明 As 是微生物垫生态系统的关键组成部分：（i）As 分布在微生物垫的所有部分，与 P（0.40%）相比，As 在垫中的重量百分比显著（0.17%）；（ii）低磷酸盐浓度在高盐度和高 As 浓度下孵育的微生物垫样品中，极大地改变了微生物群落；（iii）从微生物垫中分离出的古菌和细菌对砷酸盐（高达 500 mM）具有高度抗性，即使在低磷酸盐浓度下也是如此；（iv）两个分离株的基因组预测包含 As 代谢中的关键基因（aioAB 和 arsC/acr3），并且预测编码磷酸盐特异性转运操纵子（pstSCAB-phoU）的基因紧邻 arsC 基因，表明这两个元素之间存在功能关系。
