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Whole transcriptome analysis highlights nutrient limitation of nitrogen cycle bacteria in simulated microgravity
Tom Verbeelen1,2, Celia Alvarez Fernandez2, Thanh Huy Nguyen3
1Nuclear Medical Applications, Belgian Nuclear Research Centre (SCK CEN), Boeretang 200, 2400, Mol, Belgium.
NPJ Microgravity
|January 10, 2024
Summary
Simulated microgravity affects nitrogen recovery in space. Bacterial gene expression changes suggest nutrient limitations and increased denitrification, posing challenges for regenerative life support systems.
Area of Science:
- Space Biology
- Microbial Ecology
- Biotechnology
Background:
- Regenerative life support systems (RLSS) are crucial for long-duration space missions, enabling self-sufficiency.
- Urine conversion to fertilizer is a key process in RLSS for nitrogen recovery.
- The Micro-Ecological Life Support System Alternative (MELiSSA) project aims to develop advanced RLSS.
Purpose of the Study:
- To investigate the effects of simulated microgravity (SMG) on key bacteria involved in nitrogen recovery for RLSS.
- To analyze the transcriptional responses of Comamonas testosteroni, Nitrosomonas europaea, and Nitrobacter winogradskyi under SMG conditions.
- To assess the impact of SMG on nitrogen cycling processes relevant to space life support.
Main Methods:
- Utilized rotary cell culture systems (RCCS) and random positioning machines (RPM) as SMG analogues.
- Cultivated individual bacterial species and a tripartite culture under SMG.
- Employed specialized cell culture bags and 3D-printed holders to manage air bubbles during SMG cultivation.
- Analyzed gene expression changes to understand cellular responses to SMG.
Main Results:
- SMG conditions induced fluid dynamics leading to nutrient and oxygen limitations.
- Genes associated with urea hydrolysis and nitrification showed minimal changes.
- Denitrification-related gene expression was significantly upregulated in response to SMG.
- Bacterial cultures exhibited altered metabolic pathways under simulated microgravity.
Conclusions:
- Simulated microgravity significantly impacts bacterial nitrogen cycling relevant to RLSS.
- Increased denitrification under SMG may reduce nitrogen recovery efficiency.
- Findings highlight critical challenges for implementing robust nitrogen recovery in space-based life support systems.
- Further research is needed to optimize microbial processes for space environments.
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