There is limited knowledge of microbial carbon fixation rate, and carbon-fixing microbial abundance and diversity in saline lakes. In this study, the inorganic carbon uptake rates and carbon-fixing microbial populations were investigated in the surface sediments of lakes with a full range of salinity from freshwater to salt saturation. The results showed that in the studied lakes light-dependent bicarbonate uptake contributed substantially (>70%) to total bicarbonate uptake, while the contribution of dark bicarbonate uptake (1.35–25.17%) cannot be ignored. The light-dependent bicarbonate uptake rates were significantly correlated with pH and turbidity, while dark bicarbonate uptake rates were significantly influenced by dissolved inorganic carbon, pH, temperature and salinity. Carbon-fixing microbial populations using the Calvin-Benson-Bassham pathway were widespread in the studied lakes, and they were dominated by the cbbL and cbbM gene types affiliated with Cyanobacteria and Proteobacteria, respectively. The cbbL and cbbM gene abundance and population structures were significantly affected by different environmental variables, with the cbbL and cbbM genes being negatively correlated with salinity and organic carbon concentration, respectively. In summary, this study improves our knowledge of the abundance, diversity and function of carbon-fixing microbial populations in the lakes with a full range of salinity.

中文翻译：

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盐湖沉积物中碳酸氢盐吸收率和RuBisCO基因的多样性

关于微生物固碳率以及盐湖中固碳微生物的丰度和多样性的知识有限。在这项研究中，研究了从淡水到盐饱和的全盐度范围的湖泊表层沉积物中的无机碳吸收率和固碳微生物种群。结果表明，在所研究的湖泊中，光依赖的碳酸氢盐吸收对总碳酸氢盐吸收的贡献很大（> 70％），而暗碳酸氢盐吸收的贡献（1.35-25.17％）不容忽视。光依赖性碳酸氢盐吸收率与 pH 值和浊度显着相关，而暗碳酸氢盐吸收率受溶解无机碳、pH、温度和盐度的显着影响。使用 Calvin-Benson-Bassham 途径的固碳微生物种群在所研究的湖泊中广泛存在，它们分别以与蓝细菌和变形菌相关的 cbbL 和 cbbM 基因类型为主。cbbL和cbbM基因丰度和种群结构受不同环境变量的显着影响，cbbL和cbbM基因分别与盐度和有机碳浓度呈负相关。总之，这项研究提高了我们对各种盐度湖泊中固碳微生物种群的丰度、多样性和功能的认识。cbbL和cbbM基因丰度和种群结构受不同环境变量的显着影响，cbbL和cbbM基因分别与盐度和有机碳浓度呈负相关。总之，这项研究提高了我们对各种盐度湖泊中固碳微生物种群的丰度、多样性和功能的认识。cbbL和cbbM基因丰度和种群结构受不同环境变量的显着影响，cbbL和cbbM基因分别与盐度和有机碳浓度呈负相关。总之，这项研究提高了我们对各种盐度湖泊中固碳微生物种群的丰度、多样性和功能的认识。