Proliferation and survival analysis of rhizosphere soil bacteria in a new Mars soil simulant under Mars conditions

Growth of plants on Mars have a significant importance ranging from being an essential food source to oxygen production and raw material for manufacturing purposes, for early Mars colonists. Rhizosphere dwelling bacteria perform key functions in the growth and development of plants. In this study, the growth and survival of rhizosphere soil bacteria were examined for a period of 7 days in Khyber Pakhtunkhwa Red Mountainous Soil (KP-Mars-1), representing Mars soil simulant. KP-Mars-1 is our identified Mars soil simulant, which we characterized and refined. It exhibits similar elemental composition as Mars soil and can potentially be used as a Mars soil simulant. The simulated Mars conditions provided in this study for the analysis of bacterial growth and survival included; temperature range of + 24 °C and – 20 °C, low soil moisture content, anaerobic atmosphere (carbon dioxide dominant) and UV-C ionization radiation (200nm – 280nm). Nutrient broth culture of 3.6 mL was inoculated in 5g of KP-Mars-1. The growth and survival of rhizosphere soil bacteria were analyzed at 1, 3 & 7 days interval. Rhizosphere soil bacterial were able to survive all of the provided Mars conditions. A significant number of bacterial cells died in Mars simulated temperature and UV-C radiations. A significant growth was observed only in anaerobic (carbon dioxide dominant) conditions.