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Harnessing Microbial Communities for Advanced Life Support. J.L. Garland Dynamac Corporation, Kennedy Space Center, FL

To date microorganisms have been considered as risks to astronaut health and spacecraft integrity, and management strategies have focused on excluding disease-causing types and reducing total numbers. Introduction of bioregenerative elements (i.e., biological reactors for processing liquid or solid waste, plant production systems) into exploration missions will require a fundamentally different management strategy in which microbial communities are harnessed (i.e., controlled to use the power of) rather than minimized through disinfection or other means. Microbial oxidation of organic material to CO2  (i.e., heterotrophy) and NH4 +   to N2  (via the separate processes of nitrification and denitrification) provide the basis for wastewater treatment on Earth, and the same processes represent a potentially viable regenerable option to help recycle urine and hygiene water on near-term (i.e., Mars transit, early planetary base) exploration missions.  The unique challenge to employing biological treatment on such missions is developing small-scale bioreactors which operate reliably with little maintenance, requirements which emphasize the need to assemble efficient, stable assemblages of microorganisms. In addition, the unique nature of the spacecraft wastewater stream (i.e., high strength, low carbon/nitrogen ratio) may require the use of alternative microbial processes such as anaerobic nitrification and hydrogenotrophic denitrification. The same missions may include small scale plant systems for fresh food augmentation. Large numbers (i.e., ~1012) of microorganisms will be associated with plants, unavoidable colonists of both edible and inedible parts of the plants. Near term research requirements related to space agriculture include: 1) assessment of human health risks associated with maintaining plant systems and consuming space-grown vegetables, and 2) development of appropriate risk mitigation strategies (e.g., biocontrol approaches, and post-harvest disinfection methods). Recycling nutrients from both liquid and solid waste will become increasingly important as mission length and system self-sufficiency increase, requiring the development of microbial systems for integrating waste processing and plant growth.