Proof of Concept Testing of Low Temperature Brine Microbial Habitats for Subsurface Mars and Europa Habitat Viability Scenario Testing and Astrobiology Biosignature Instrument Development

Presented is a synopsis of ongoing research into the development of techniques and hardware required to produce useable quantities of astrobiology relevant biomass under controlled and repeatable laboratory conditions. This study has developed microbial habitats (referred to as digesters, due to their biomass production function) capable of sustaining microbial communities under low temperature, high salt, high sulfate, anaerobic conditions. This set of basic conditions is necessary to develop biomass material that is analog to the biomass that would be present in subsurface brine habitats on Mars or Europa, from the perspective of several critical biochemical properties.

Stable microbial biomass production and substrate utilization of acetate and sulfate was achieved at temperatures from 7°C to −1°C (psychrophilic), ionic strength and composition of Earth normal seawater or approximately 3.5 % as NaCl (mildly halophilic), high sulfate concentrations of up to 2,000 mg/L SO₄²⁻, and strictly anaerobic conditions. Under these conditions, substantial substrate utilization was monitored, to include robust metabolic activity at −1°C.