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.

On the multiplication of xerophilic micro-organisms under simulated Martian conditions.

The environmental conditions prevailing on Mars would supposedly favour the existence there of micro-organisms belonging to xerophiles, anaerobes, or micro-aerophiles, oligonitrophiles, which are able to grow in wide temperature intervals. From soil samples taken in deserts and tundra, antarctic halophilic bacteria, able to grow in liquid media containing 20-25% of sodium chloride, were isolated. Some of these cultures appeared to be also osmophilic (growth on media with 50% glucose); they grew at temperatures from 5 degrees C to 50 degrees C, and developed on media without a nitrogen source (oligonitrophiles).

Multiplication of certain soil micro-organisms under simulated Martian conditions.

According to earlier observations, severe UV irradiation kills all micro-organisms in a chamber with simulated Martian conditions. However, even a thin soil layer protects buried micro-organisms from UV irradiation. The chief limiting factor for microbial multiplication under simulated Martian conditions seems to be soil humidity.