Biological studies of Martian soil analogues.

Results of the study of the influence of Martian soil analogues, both as described by American scientists and as prepared by us, and of hydrogen peroxide on the viability of microorganisms are presented. The experiments were carried out using mixtures of soil analogues with desert soil and black earth (chernozem) samples, and pure cultures of microorganism. Microorganisms capable of withstanding a concentration of hydrogen peroxide in the medium as high as 1.

On different sensitivities of microorganisms to lowered gravitation.

The influence of lowered gravitation on biomass and CO2 production in B. megaterium, a xerophyte, and Spirillum azotocolligens, an aqueous spirillum, in liquid nutrient medium on a horizontal clinostat at 0.1 g has been studied.

Microorganisms of the upper layer of the atmosphere and the protective role of their cell pigments.

Of the six species of microorganisms isolated from the mesosphere, five contained pigments and were more resistant to UV radiation compared with their pigment-free mutants. The black pigment isolated from the conidia of Aspergillus niger considerably increased the UV resistance of the unpigmented mutant conidia of Penicillium notatum, the spore Circinella muscae and the vegetative cells of Micrococcus albus. From the data it is possible to conclude that in the upper layers of the Earth's atmosphere the predominant proportion of pigmented microorganisms is the consequence of natural selection by UV radiation.

Upper boundary of the biosphere.

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.

Physiology of xerophytic micro-organisms growing under Martian conditions.

The main factor limiting growth of terrestrial organisms under Martian conditions is the low humidity; therefore the biology of xerophytic micro-organisms has been studied. We found earlier that Bacillus megaterium var. halotolerant and Mycococcus ruber could survive and grow under Martian conditions.