Metabolomics Differential Analysis Reveals Clinostat Rotation Affects Metabolite Transportation and Increases Organic Acid Production of Aspergillus carbonarius

Contamination by fungi may pose a threat to the long-term operation of the space station because fungi produce organic acids that corrode equipment and mycotoxins that harm human health. Microgravity is an unavoidable and special condition in the space station. However, the influence of microgravity on fungal metabolism has not been well studied. Clinostat rotation is widely used to simulate the microgravity condition in studies carried out on Earth. Here, we used metabolomics differential analysis to study the influence of clinostat rotation on the accumulation of organic acids and related biosynthetic pathways in ochratoxin A (OTA)-producing Aspergillus carbonarius . As results, clinostat rotation did not affect fungal cell growth or colony appearance, but significantly increased the accumulation of organic acids and OTA both inside cells and in the medium, particularly isocitric acid, citric acid, oxalic acid, as well as a much higher accumulation of some products inside than outside cells, indicating that transport of these metabolites from the cell to the medium was inhibited. This finding corresponded with the change in fatty acid composition of cell membranes and reduced thickness of the cell walls and cell membranes. Amino acid and energy metabolic pathways, particularly the TCA cycle was influenced the most during clinostat rotation compared to normal gravity. IMPORTANCE Fungi are ubiquitous in nature and have the ability to corrode various materials by producing metabolites. Research on how the space station environment, especially microgravity, affects fungal metabolism is helpful to understand the role of fungi in space station. This work provides insights on the mechanisms involved in metabolism of corrosive fungus Aspergillus carbonarius under simulated microgravity condition. Our findings have significance not only for preventing material corrosion, but also for ensuring food safety, especially in the space environment.