Upper boundary of the biosphere

Abstract

By using meterological rockets fitted with specially designed analyzers, samples for microbiological investigation have been taken. The analyzer design prevented extraneous microorganisms from penetrating into the analyzer. Before being used, the analyzers were sterilized with high gamma-ray doses. For the first time microorganisms have been detected in the mesosphere at an altitude of 48 to 77 km. The microorganisms are microscopic fungi having black conidia or spores (Circinella muscae, Aspergillus niger, Papulaspora anomala) and one species forming green conidia (Penicillium notatum). Colonies of Mycobacterium luteum and Micrococcus albus have also grown. Five of the six species have synthesized pigments. The presence of pigmented microbial forms leads us to believe that natural selection is occurring in the mesosphere because cells possessing chromogenous pigments (carotenoids, melanins) are more resistant to ultraviolet-ray action. A greater number of microorganisms have been registered in the mesosphere during dust storms than in the absence of strong winds.

Long‐range Transmission of Bacteria

“…By using a rocket microorganisms were detected as far up as 48-77 km. 55 The bacteria were of the genera Mycobacterium and Micrococcus. Five of the six species had chromogenic pigments that is claimed to be more resistant to ultraviolet rays.55 However in this investigation no Bacillus spores were detected.…”

Characterization of ice‐nucleating bacteria using on‐line electron impact ionization aerosol mass spectrometry

“…Airborne bacteria have been identified in various parts of the atmosphere including remote locations such as desert regions [1][2][3] and as high as 50 km in the stratosphere. [4] They have been found in cloud water, [5,6] ice-crystals and snow [7,8] as well as fog droplets. [9] In the upper troposphere, viable bacteria appear to be the prevailing microorganisms and can represent up to around 20% of the total number of particles between 0.25 and 1 μm in diameter.…”

Role of pigmentation in protecting Bacillus sp. endospores against environmental UV radiation

“…Their high resistance to environmental extremes makes these spores also ideal model systems for testing their responses to extraterrestrial conditions, such as outer space [2] or simulated planetary conditions [3]. Among fungal and bacterial spores collected at high altitudes up to 77 km [4], pigmented forms dominated. It has al-ready been suggested in this early work that endogenous pigments, such as carotenoids and melanins, might provide a selective advantage to these microorganisms by shielding from environmental UV radiation, which at these high altitudes comprises the full extraterrestrial spectrum, including the UV-C and full UV-B range.…”