Slide Sign up Order Now The Effect of Microgravity on
Nitrogen Fixing Bacteria with Cowpeas


The Effects of Microgravity on Microbial Nitrogen Fixation (Microbial Nitrogen Fixation) studies two species of soil-dwelling bacteria to understand the effects of microgravity on microbial nitrogen fixation. Azotobacter vinelandii, a free living strain, and Rhizobium leguminosarum, a symbiotic strain that infects the root systems of leguminous plants are the experimental organisms. Escherichia coli (not capable of nitrogen fixation) is included as a negative control.









Why are we researching nitrogen fixing bacteria?

As a follow-on to Flight 6, will fly cowpea (Vigna unguiculata) seedlings in a 3-tube 2u lab. These species of legumes, nodulate with R. leguminosarum and are important food crops. This species are also more heat tolerant than other leguminous food crops. By flying seedlings, we are able to select the best specimens for flight and reduce the need for cold stow & late load.

Two tubes of experimental seedlings (rhizobium inoculated) and one tube as a control seedlings (uninoculated)  will be on orbit for 4-6 weeks. Approximately L -7 to -10 days pre-launch, seeds are “planted”. At L-3, the best seedlings are selected and loaded into the ExoLab. Classrooms will need to start at L-planting days to properly sync with the orbital lab.

This experiment further explores the potential of sustainably cropping in space. By assessing the viability of legumes and their ability to nodulate with Rhizobium in microgravity, we will make steps in evaluating if legumes could be potential food crops for human space exploration. If successful, other crops that are nitrogen intensive to grow will have a natural source of nitrogen through the production of excess fixed nitrogen by the Rhizobial nodules of legumes.

Finally, elevated temperature and carbon dioxide levels on the International Space Station will also provide insight into how this important symbiosis may be affected by climate change.


Space Application

Nitrogen fixation is an essential process of agricultural systems and a necessary component for translating agriculture to spaceflight environments. The results of this study further our understanding of how specific strains of bacteria can aid in the successful growth of crops in space.

Slide Flight hardware by SpaceTango

Duration of Experiment

The experiment will launch on 2/9/2020 aboard NG-13 and will returns on 4/2/2020 aboard SpX-20. Following installation the International Space Station, it will run for 7 – 8 weeks and moved to cold storage until return on the Dragon Capsule.

Flight Schedule

ExoLab #DateResupply MissionExperiment
1Feb 2017SpX-10Arabidopsis thaliana
2October 2017OA-8Arabidopsis thaliana
3April 2018SpX-14Arabidopsis thaliana
4July 2018SpX-15Amaranth, Chard, Mizuna, Purslane
5Dec 2018SpX-16 Amaranth, Pak Choy, Purslane, Wasabi
6July 2019SpX-18Rhizobium Legumin
7Feb 2020
NG-13 (returns on SpX-20 4/2/2020)
Rhizobium Inoculum
8Feb 2021NG-15 - SpX-22 (return)Legume in Space

Slide Flight hardware by SpaceTango

Earth Application

Soil microflora are critical to converting nutrients into forms that can be absorbed and utilized by plants. The Microbial Nitrogen Fixation experiment informs our understanding of nitrogen fixation responses of selected microbes in microgravity, with potential to improve our understanding of the impact of climate change on soil productivity.

Astronaut Peggy Whitson installs the ExoLab, ISS Exp.

Classroom Protocols

Students will run ground analogs to the Flight 6 experiment in two parts, first with Rhizobia, followed by Azotobacter. Each trial will consist of four petri dishes. Students will document and share observations with the ExoLab network.

Slide Flight hardware by SpaceTango

Classroom Involvement

Ground versions of the CubeLab, known as the ExoLab, are distributed in schools across the United States, Canada, South Africa and Germany. These schools collaborate, through the platform, in the investigation of the effects of the microgravity environment. Students are able to compare the experiment onboard the International Space Station alongside their own classroom lab, as well as the labs in other schools in the network.

Slide ExoLab: Ground Analog loaded with bacteria cultures for observation and comparison to the Lab on Orbit. Side-by-Side comparison of classroom and orbital labs

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