| Cell Cultures | Mammalian and plant experiments are possible without experiment and hardware requirements necessary for vertebrates or large plants | Mammalian cell culture Specifically, cell types related to the Human Research Program risk gaps | Not applicable | Organ on a chip | Plant cell culture | Organ on a chip (JJ) | Open | Mammalian, human and plant cell cultures Organ on a chip |
| Model Bacteria and Archaea | Extensive published understanding of organism characteristics, often with flight heritage and established experimental systems | Single-celled bacteria and archaea |
Representatives of functional guilds of interest: photosynthetic, anaerobic, nitrogen cycle, carbon cycle, etc. Stress tolerant microbes: radiation tolerant, spore formers, psychrophiles, etc. | Not applicable | Pathogenic and plant growth promoting bacteria Cyanobacteria |
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Bacillus Deinococcus Escherechia Pseudomonas Salmonella Cyanobacteria | Single-celled bacteria and archaea |
| Model Eukarya | Extensive published understanding of organism characteristics, often with flight heritage and established experimental systems |
Single-celled yeasts Arabidopsis | Representatives of fungi and protists that carry out specific functions and/or are stress tolerant. | Yeasts Small animal eukaryote e.g. worms, flies, fish Mus | Green algae including Chlorella Moss species Arabidopsis Crop species as seeds and mature plants e.g. lettuce, tomato, peppers, maize | Arabidopsis Crop species e.g. lettuce, mizuna, peppers Hydra Rotifers Chlorella | Green algae i.e. Chlorella Yeasts and filamentous fungi Small animal eukaryotes e.g. Nematodes and Tardigrades Small plants e.g. Brassica cultivars, Arabidopsis | Single-celled yeasts Filamentous fungi |
| Organisms Useful for Targeted Functions or Questions | Studies of specific species, biological behaviors or processes of interest in spaceflight and BLEO; can include non-model organisms | Engineered organisms e.g. with promoter-reporter constructs, fluorescent protein vector | Nitrogen-cycle bacteria Oxygenic and anoxygenic photosynthetic bacteria Sulfur metabolism Halotrophy and radiation resistance Chemo- and autotrophic metabolisms | Open | Pathogenic and plant growth promoting bacteria Plants suited for efficient food production (tubers, beets, microgreens) | Probiotics for plants and humans | Nitrogen-cycle bacteria Oxygenic and anoxygenic photosynthetic bacteria Chemo- and autotrophic metabolisms | Chemolithoautotrophs Thermophiles |
| Co-Cultures | The effects of the BLEO environment on interaction effects between organisms in a defined and controlled manner | Open | Metabolic interactions of microbes and coordinated functions Symbiosis, commensalism and syntrophy Competition and predation | Open | Pathogenic and plant growth promoting bacteria | Hydra and algae Model host-microbe symbiotic systems e.g. hydra and algae Organ-on-a-chip (human cells co-cultured with specific microbes) | Plant-associated and plant growth promoting bacteria Symbiosis, commensalism and syntrophy Competition and predation | Syntrophy |
| Complex Communities | The responses of complex, natural communities to the BLEO and extreme built environment that cannot be reliably predicted from reductionist approaches. | Combined phenotypes |
Synthetic model communities Naturally-evolved communities e.g. soils, microbial mats Cell cultures of gut, skin, plant with associated microbes. Built microbiome (potential living space BLEO) | Not applicable | Naturally-evolved communities e.g. soils Gut-, skin-, plant- and built-microbiome | Gut-, skin-, plant- and built-microbiome Termites | Synthetic model communities Gut-, skin-, plant- and built-microbiome | Biofilms |
