Li Qi, Hu Chunxiang, Yang Haijian
Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China.
University of Chinese Academy of Sciences, Beijing 100049, China.
Microorganisms. 2022 Jun 19;10(6):1252. doi: 10.3390/microorganisms10061252.
How microbial communities respond to extreme conditions in the stratosphere remains unclear. To test this effect, cyanobacterial crusts collected from Tengger Desert were mounted to high balloons and briefly exposed (140 min) to high UV irradiation and low temperature in the stratosphere at an altitude of 32 km. Freezing and thawing treatments were simulated in the laboratory in terms of the temperature fluctuations during flight. Microbial community composition was characterized by sequencing at the level of DNA and RNA. After exposure to the stratosphere, the RNA relative abundances of and increased by about 2-fold, while those of several dominant cyanobacteria genera changed slightly. The RNA relative abundances of various taxa declined after freezing, but increased after thawing, whereas cyanobacteria exhibited an opposite change trend. The DNA and RNA relative abundances of Nitrososphaeraceae were increased by 1.42.3-fold after exposure to the stratosphere or freezing. Exposure to stratospheric environmental conditions had little impact on the total antioxidant capacity, photosynthetic pigment content, and photosynthetic rate, but significantly increased the content of exopolysaccharides by 16%. The three treatments (stratospheric exposure, freezing, and thawing) increased significantly the activities of N-acetyl-β-D-glucosidase (2630%) and β-glucosidase (14~126%). Our results indicated cyanobacterial crust communities can tolerate exposure to the stratosphere. In the defense process, extracellular organic carbon degradation and transformation play an important role. This study makes the first attempt to explore the response of microbial communities of cyanobacterial crusts to a Mars-like stratospheric extreme environment, which provides a new perspective for studying the space biology of earth communities.
微生物群落如何应对平流层中的极端条件仍不清楚。为了测试这种影响，将从腾格里沙漠采集的蓝藻地衣附着在高空气球上，并在32公里高空的平流层中短暂暴露（140分钟）于高紫外线辐射和低温环境。根据飞行过程中的温度波动在实验室中模拟了冻融处理。通过对DNA和RNA水平进行测序来表征微生物群落组成。暴露于平流层后，[具体物种1]和[具体物种2]的RNA相对丰度增加了约2倍，而几个优势蓝藻属的RNA相对丰度变化较小。各种分类群的RNA相对丰度在冷冻后下降，但在解冻后增加，而蓝藻则呈现相反的变化趋势。暴露于平流层或冷冻后，硝化球菌科的DNA和RNA相对丰度增加了1.4至2.3倍。暴露于平流层环境条件对总抗氧化能力、光合色素含量和光合速率影响不大，但胞外多糖含量显著增加了16%。三种处理（平流层暴露、冷冻和解冻）均显著提高了N-乙酰-β-D-葡萄糖苷酶（26%至30%）和β-葡萄糖苷酶（14%至126%）的活性。我们的结果表明蓝藻地衣群落能够耐受平流层暴露。在防御过程中，细胞外有机碳的降解和转化起着重要作用。本研究首次尝试探索蓝藻地衣微生物群落对类火星平流层极端环境的响应，为研究地球群落的空间生物学提供了新的视角。
