Xamxidin Maripat, Zhang Xuanqi, Zheng Gang, Chen Can, Wu Min
College of Life Sciences, Zhejiang University, Hangzhou, China.
College of Architecture and Engineering, Zhejiang University, Hangzhou, China.
Front Microbiol. 2025 Jun 4;16:1550346. doi: 10.3389/fmicb.2025.1550346. eCollection 2025.
Salt-tolerant and halophilic microorganisms are critical drivers of ecosystem stability and biogeochemical cycling in athalassohaline environments. Lake Barkol, a high-altitude inland saline lake, provides a valuable natural setting for investigating microbial community dynamics and adaptation mechanisms under extreme salinity. In this study, we employed high-throughput metagenomic sequencing to characterize the taxonomic composition, metabolic potential, and ecological functions of microbial communities in both water and sediment samples from Lake Barkol. We reconstructed 309 metagenome-assembled genomes (MAGs), comprising 279 bacterial and 30 archaeal genomes. Notably, approximately 97% of the MAGs could not be classified at the species level, indicating substantial taxonomic novelty in this ecosystem. Dominant bacterial phyla included , , , , and , while archaeal communities were primarily composed of , , and . Metabolic reconstruction revealed the presence of diverse carbon fixation pathways, including the Calvin-Benson-Bassham (CBB) cycle, the Arnon-Buchanan reductive tricarboxylic acid (rTCA) cycle, and the Wood-Ljungdahl pathway. Autotrophic sulfur-oxidizing bacteria, alongside members of and , were implicated in primary production and carbon assimilation. Nitrogen metabolism was predominantly mediated by , with evidence for both nitrogen fixation and denitrification processes. Sulfur cycling was largely driven by and , contributing to sulfate reduction and sulfur oxidation pathways. Microbial communities exhibited distinct osmoadaptation strategies. The "salt-in" strategy was characterized by ion transport systems such as Trk/Ktr potassium uptake and Na/H antiporters, enabling active intracellular ion homeostasis. In contrast, the "salt-out" strategy involved the biosynthesis and uptake of compatible solutes including ectoine, trehalose, and glycine betaine. These strategies were differentially enriched between water and sediment habitats, suggesting spatially distinct adaptive responses to local salinity gradients and nutrient regimes. Additionally, genes encoding microbial rhodopsins were widely distributed, suggesting that rhodopsin-based phototrophy may contribute to supplemental energy acquisition under osmotic stress conditions. The integration of functional and taxonomic data highlights the metabolic versatility and ecological roles of microbial taxa in sustaining biogeochemical processes under hypersaline conditions. Overall, this study reveals extensive taxonomic novelty and functional plasticity among microbial communities in Lake Barkol and underscores the influence of salinity in structuring microbial assemblages and metabolic pathways in athalassohaline ecosystems.
耐盐和嗜盐微生物是无海迹盐湖环境中生态系统稳定性和生物地球化学循环的关键驱动因素。巴里坤湖是一个高海拔内陆盐湖，为研究极端盐度下微生物群落动态和适应机制提供了宝贵的自然环境。在本研究中，我们采用高通量宏基因组测序来表征巴里坤湖水体和沉积物样本中微生物群落的分类组成、代谢潜力和生态功能。我们重建了309个宏基因组组装基因组（MAG），包括279个细菌基因组和30个古菌基因组。值得注意的是，约97%的MAG在物种水平上无法分类，表明该生态系统中存在大量的分类学新物种。优势细菌门包括 、 、 、 和 ，而古菌群落主要由 、 和 组成。代谢重建揭示了多种碳固定途径的存在，包括卡尔文-本森-巴斯姆（CBB）循环、阿农-布坎南还原性三羧酸（rTCA）循环和伍德-Ljungdahl途径。自养硫氧化细菌以及 和 的成员参与了初级生产和碳同化。氮代谢主要由 介导，有固氮和反硝化过程的证据。硫循环主要由 和 驱动，促进了硫酸盐还原和硫氧化途径。微生物群落表现出不同的渗透适应策略。“盐入”策略的特征是离子运输系统，如Trk/Ktr钾吸收和Na/H反向转运蛋白，能够实现细胞内主动的离子稳态。相比之下，“盐出”策略涉及相容性溶质的生物合成和吸收，包括四氢嘧啶、海藻糖和甘氨酸甜菜碱。这些策略在水体和沉积物栖息地之间差异富集，表明对局部盐度梯度和营养状况存在空间上不同的适应性反应。此外，编码微生物视紫红质的基因广泛分布，表明基于视紫红质的光养作用可能有助于在渗透胁迫条件下获取补充能量。功能和分类数据的整合突出了微生物类群在高盐条件下维持生物地球化学过程中的代谢多功能性和生态作用。总体而言，本研究揭示了巴里坤湖微生物群落中广泛的分类学新物种和功能可塑性，并强调了盐度对无海迹盐湖生态系统中微生物群落结构和代谢途径的影响。
