Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, USA.
Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA.
ISME J. 2019 Nov;13(11):2789-2799. doi: 10.1038/s41396-019-0474-0. Epub 2019 Jul 17.
Bioaerosol transport in the atmosphere disperses microbial species between continents, affects human and plant health, and may influence hydrologic cycling. However, there have been few quantitative observations of bioaerosols at altitudes more than a few kilometers above the surface. Lack of data on bioaerosol distributions in the atmosphere has impeded efforts to assess the aerial dissemination of microbes and their vertical extent in the biosphere. In this study, a helium balloon payload system was used to sample microbial cells and dust particles in air masses as high as 38 km above sea level over three locations in the southwestern United States. The cell concentrations at altitudes between 3 and 29 km were highly similar (2-5 × 10 cells m) and approximately threefold lower than those observed in the convective boundary layer (CBL; 1 × 10 cells m), decreasing to 8 × 10 cells m at 35-38 km. The detection of adenosine triphosphate (ATP) and recovery of bacteria possessing extreme tolerance to desiccation and shortwave ultraviolet radiation confirmed that certain microorganisms have the capacity to persist at lower altitudes of the stratosphere. Our data and related calculations provide constraints on the upper altitudinal boundary for microbial habitability in the biosphere.
大气中的生物气溶胶在大陆之间传播微生物物种，影响人类和植物健康，并可能影响水文循环。然而，在离地面几公里以上的高度对生物气溶胶进行定量观测的情况却很少。由于缺乏有关大气中生物气溶胶分布的数据，因此难以评估微生物在空气中的传播及其在生物圈中的垂直分布范围。在这项研究中，使用氦气球有效载荷系统在三个美国西南部的地点采集了高达 38 公里以上的高空大气中微生物细胞和尘埃颗粒。在 3 到 29 公里的高度上，细胞浓度非常相似（2-5×10 个细胞 m），大约比在对流层边界层（CBL）中观察到的低三倍（1×10 个细胞 m），在 35-38 公里处降低到 8×10 个细胞 m。三磷酸腺苷（ATP）的检测和对具有极端耐干燥和短波紫外线辐射能力的细菌的回收证实，某些微生物有能力在平流层的较低海拔高度生存。我们的数据和相关计算为生物圈中微生物可居住性的高空边界提供了限制。
