Reactivation of Microbial Strains and Synthetic Communities After a Spaceflight to the International Space Station: Corroborating the Feasibility of Essential Conversions in the MELiSSA Loop

Abstract

To sustain human deep space exploration or extra-terrestrial settlements where no resupply from the Earth or other planets is possible, technologies for in situ food production, water, air, and waste recovery need to be developed. The Micro-Ecological Life Support System Alternative (MELiSSA) is such a Regenerative Life Support System (RLSS) and it builds on several bacterial bioprocesses. However, alterations in gravity, temperature, and radiation associated with the space environment can affect survival and functionality of the microorganisms. In this study, representative strains of different carbon and nitrogen metabolisms with application in the MELiSSA were selected for launch and Low Earth Orbit (LEO) exposure. An edible photoautotrophic strain (Arthrospira sp. PCC 8005), a photoheterotrophic strain (Rhodospirillum rubrum S1H), a ureolytic heterotrophic strain (Cupriavidus pinatubonensis 1245), and combinations of C. pinatubonensis 1245 and autotrophic ammonia and nitrite oxidizing strains (Nitrosomonas europaea ATCC19718, Nitrosomonas ureae Nm10, and Nitrobacter winogradskyi Nb255) were sent to the International Space Station (ISS) for 7 days. There, the samples were exposed to 2.8 mGy, a dose 140 times higher than on the Earth, and a temperature of 22°C -1°C. On return to the Earth, the cultures were reactivated and their growth and activity were compared with terrestrial controls stored under refrigerated (5°C -2°C) or room temperature (22°C -1°C and 21°C -0°C) conditions. Overall, no difference was observed between terrestrial and ISS samples. Most cultures presented lower cell viability after the test, regardless of the type of exposure, indicating a harsher effect of the storage and sample preparation than the spaceflight itself. Postmission analysis revealed the successful survival and proliferation of all cultures except for Arthrospira, which suffered from the premission depressurization test. These observations validate the possibility of launching, storing, and reactivating bacteria with essential functionalities for microbial bioprocesses in RLSS.

Shotgun metagenomic analysis of kombucha mutualistic community exposed to Mars‐like environment outside the International Space Station

“…Moreover, microbial consortia (or their monocultures) will be crucial players in biotechnology, allowing the production of key‐products needed for space crews (Lopez et al ., 2019). The application of such microbial communities in extraterrestrial habitats for food and health, as well as for waste recycling, is absolutely necessary as microorganisms are an inalienable component of Bio‐Regenerative Life Support System (BRLSS) (Huang et al ., 2018; Ilgrande et al ., 2019).…”

Development of Nitrogen Recycling Strategies for Bioregenerative Life Support Systems in Space

“…Here, nitrogen is effectively converted to the form preferred by plants or cyanobacteria. It serves as a fertilizer in the subsequent biomass-and oxygen-producing and CO 2 -consuming compartment IV ( Farges et al, 2012 ; Clauwaert et al, 2017 ; Ilgrande et al, 2019b ). The final compartment V is the crew, who is consuming produced biomass and O 2 on the one hand, and producing CO 2 , urine and fecal waste on the other hand.…”

“…However, CIII cannot be used to directly process urine at present. Urine currently enters CI together with other waste products ( Ilgrande et al, 2019b ). Urea can be converted to ammonium by ureolytic bacteria through the action of the hydrolytic urease enzyme ( Defoirdt et al, 2017 ; Ilgrande et al, 2019a ).…”

“…In LEO, the metabolism of the ureolytic and nitrifying bacteria could be affected by increased ionizing radiation dose rates and changes in gravity conditions ( Senatore et al, 2018 ; Milojevic and Weckwerth, 2020 ). Both spaceflight experiments and simulations on Earth have been conducted to observe and gain a broad understanding of the bacterial responses and, more importantly, to assess the feasibility of a BLSS for space exploration ( Leys et al, 2009 ; Mastroleo et al, 2009 , 2013 ; Lindeboom et al, 2018 ; Ilgrande et al, 2019b ; Poughon et al, 2020 ; Senatore et al, 2020 ). It is, however, extremely challenging to perform flight experiments to assess the biological effects of a real space environment due to the high costs and great interest in flying an experiment in combination with limited crew time and space aboard the ISS and other space stations.…”

“…Furthermore, two spaceflight experiments (NITRIMEL and BISTRO) have been conducted to specifically study the effects of space conditions on nitrifying bacteria and consortia. Both focused on the storage and survival of inactivated cultures of nitrifiers, rather than assessing the effects of space conditions on active cultures and the active nitrogen conversion process ( Lindeboom et al, 2018 ; Ilgrande et al, 2019b ). The impact of space conditions on reactivation ability of the nitrogen cycle cultures is important in case of system failure during spaceflight ( Lindeboom et al, 2018 ).…”