The Impacts of Microgravity on Bacterial Metabolism

Abstract

The inside of a space-faring vehicle provides a set of conditions unlike anything experienced by bacteria on Earth. The low-shear, diffusion-limited microenvironment with accompanying high levels of ionizing radiation create high stress in bacterial cells, and results in many physiological adaptations. This review gives an overview of the effect spaceflight in general, and real or simulated microgravity in particular, has on primary and secondary metabolism. Some broad trends in primary metabolic responses can be identified. These include increases in carbohydrate metabolism, changes in carbon substrate utilization range, and changes in amino acid metabolism that reflect increased oxidative stress. However, another important trend is that there is no universal bacterial response to microgravity, as different bacteria often have contradictory responses to the same stress. This is exemplified in many of the observed secondary metabolite responses where secondary metabolites may have increased, decreased, or unchanged production in microgravity. Different secondary metabolites in the same organism can even show drastically different production responses. Microgravity can also impact the production profile and localization of secondary metabolites. The inconsistency of bacterial responses to real or simulated microgravity underscores the importance of further research in this area to better understand how microbes can impact the people and systems aboard spacecraft.

Experimentally Created Magnetic Force in Microbiological Space and On-Earth Studies: Perspectives and Restrictions

“…The net effect of microgravity on bacteria may be distinct in its dependence on such parameters as a tested strain, medium composition or a growth stage (reviewed in [2,4,24,82]. Better availability of nutrients for non-sedimenting bacteria provide their better growth at exponential and early stationary growth.…”

“…However, financial, safety and time restrictions on space studies have required development of on-Earth models to study specific microgravity features. For bacteria growing in liquid media, spaceflight conditions provide weightlessness, lack of sedimentation, and low shear conditions due to the absence of convectional flows within the liquid [1,24]. A number of on-Earth models were developed that mimic these hallmarks of microgravity.…”

Biomanufacturing for Space-Exploration – What to Take and When to Make

“…Readying Microbial Production Systems for off-world Bio-ISM While having gained significant traction over the last decade, the study of space biomanufacturing is still limited to small-scale microgravity experiments [86][87][88] (e.g., BioRock 89 or Rhodium Inflight Biomanufacturing 90 ). More extensive R&D will be required to ready bio-ISM technologies for implementation in mission architectures, especially to scale and adapt synthetic biology and bioprocess engineering to the relevant (off-world) environments (specifically Moon and Mars) 21,91 . To this end, the development of microbial cell factories must go hand-in-hand with the development of appropriate hardware for in-space bio-ISM.…”

Viruses in astrobiology

“…The same possibility could be applied to extraterrestrial virospheres. In addition to viral adaptations to extreme environments, viruses have been shown –in experimental setups– to survive high doses of UV radiation, ionizing radiation, X rays, high vacuum, desiccation, or microgravity conditions ( Koike et al, 1992 ; Hegedüs et al, 2006 ; Horneck et al, 2010 ; Vaishampayan and Grohmann, 2019 ; Sharma and Curtis, 2022 ), a fact that would support their possible involvement in the transport of genetic material between planets. Particular consideration deserves the finding that under simulated hot spring conditions, viruses can fossilize upon the aggregation of silica deposits ( Laidler and Stedman, 2010 ; Orange et al, 2011 ).…”