青藏高原湖泊总面积4.9万平方公里，占全国湖泊总面积49％，是世界海拔最高、面积最大的湖泊群和盐碱湖群。固碳微生物在低温、盐碱环境中广泛存在，并为这些极端环境生态系统提供初级生产力。然而，青藏高原湖泊微生物固碳生命过程及其固碳能力尚未研究。因此，全球CO2增加情景下研究青藏高原高海拔、低温、高紫外及不同盐度湖泊中固碳微生物功能群特征及其固碳能力成为最紧迫的重大科学问题之一。该项目依托中国科学院青藏高原研究所野外台站，采用分子生物学与环境因子分析方法，将研究青藏高原13个不同盐度湖泊水体和沉积物中总微生物群落（细菌、真菌和古菌）和固碳微生物功能群特征、适应性进化、固碳能力、时空分布（不同湖泊、不同深度、不同季节）及其环境因子驱动机制，揭示总微生物群落与固碳微生物功能群种属分化特征，认识高寒湖泊微生物群落特征及固碳能力，为评估湖泊微生物固碳对青藏高原地区碳收支平衡的贡献提供基础数据和理论依据。

Tibetan Plateau (TP) hosts thousands of saline and alkaline lakes, approximately 49,000 km2 in total, representing 49% of all Chinese lake area. This lake region represents the Earth's highest in altitude and the largest in area on the Earth. This is true to saline and alkaline lakes. Increasing evidence has documented that CO2-fixing microbes widely inhabit in saline and alkaline aquatic environments with low temperatures, providing primary production to these extreme ecosystems. However, knowledge of CO2-fixing microbial community remains obscure in the Tibetan lakes. Thus, characterizing CO2-fixing microbial community in the Tibetan lakes characteristic of low temperature and high UV has been one of the most important questions with the background of the global CO2 rise. This proposal herein aims to study the overall and CO2-fixing microbial community properties (abundance, diversity, evolution, gene expression, CO2-fixing potential, spatial and temporal patterns) and driving factors of the overall and CO2-fixing microbes in saline and alkaline lakes along a precipitation gradient on the TP. This will unveil CO2-fixing microbial community characteristics and its role in balancing carbon budget in this region.