Selection and characterization of bacterial consortia for the degradation of space organic waste

Planned human exploration beyond low Earth orbit involves establishing long-term Moon and Mars settlements. Due to the impracticality of continuous resupply from Earth for such missions, it is crucial to develop systems that allow partial or complete in situ recycling of resources necessary for human survival, such as Bioregenerative Life Support Systems (BLSSs), closed artificial ecosystems providing oxygen, food, and water. Microorganisms can play an important role in BLSSs for space missions by producing oxygen, removing carbon dioxide, and degrading organic waste such as food scraps, inedible plant portions, and human faeces. This study aimed to select and identify bacterial communities capable of efficiently degrading organic waste generated during space missions. Bacterial degraders were enriched through sequential batch cultivation in a simulated organic waste mixture like that generated on the International Space Station. Two promising bacterial consortia with high Enterococcus and Clostridia genera abundance, commonly involved in organic waste degradation, were selected. During fermentation, a significant reduction (p < 0.05) in the mass of organic waste, cellulose, and starch content was observed after inoculating the organic waste mixture with the two selected consortia.