Microbiological characterization of a regenerative life support system

Area of Science:

• Microbiology
• Astrobiology
• Plant Science

Background:

• Controlled environment agriculture is crucial for long-duration space missions.
• Understanding microbial ecosystems within plant growth systems is essential for crew health and mission success.
• The Johnson Space Center's Regenerative Life Support Systems (RLSS) test bed utilizes advanced chambers for space agriculture research.

Purpose of the Study:

• To characterize the microbiological diversity within a Variable Pressure Plant Growth Chamber (VPGC) during soil-grown lettuce cultivation.
• To quantify bacterial and fungal populations in various components of the VPGC system.
• To identify predominant microbial genera in the chamber environment.

Main Methods:

• Lettuce was grown in a VPGC at the Johnson Space Center's RLSS test bed.
• Samples were collected from the rhizosphere, spent nutrient medium, heat exchanger condensate, and atmosphere.
• Microbiological analysis was performed to determine bacterial and fungal counts (CFU) and identify dominant genera.

Main Results:

• Bacterial populations reached approximately 10(11) CFU g-1 in the rhizosphere and 10(5) CFU ml-1 in the nutrient medium and condensate.
• Fungal populations were around 10(5) CFU g-1 in the rhizosphere and varied in other components.
• Pseudomonas was the predominant bacterial genus, while Fusarium and Trichoderma were the dominant fungal genera.

Conclusions:

• The VPGC system supports a robust microbial community during lettuce growth.
• Knowledge of these microbial dynamics is vital for designing safe and productive bioregenerative life support systems for space exploration.
• Further research can focus on managing these microbial populations for optimal crop production and safety.