Transcriptomic Analysis Reveals the Molecular Events in Aspergillus niger under High Aspect Ratio Vessel Simulated Microgravity

Aspergillus niger is known as a common contaminant in space station environments. It has been used as a model fungus for studying enzyme production in eukaryotes. In this study, a reference-based RNA-sequencing transcriptomic analysis was conducted to examine the biological response of A. niger under simulated microgravity conditions. Assuming that microgravity represents a distinctive environmental stimulus, understanding its effects on fungal behavior is crucial, predominantly in the context of astronaut health and biotechnological applications. Environmental factors such as low pressure and low temperature are known to influence enzyme production in A. niger. Therefore, genes encoding industrially relevant enzymes were screened for differential expression to assess the impact of simulated microgravity. Remarkably, a significant upregulation of enzyme-coding genes was observed at 12 h of incubation under microgravity, with sustained expression through 48 h. Annotation against a reference database and differential expression analysis using DESeq revealed an increase in secondary metabolite genes expression under simulated microgravity compared to normal gravity conditions. However, our result showed that A. niger did not exhibit upregulation of genes associated with pathogenicity. These results suggested that A. niger responded to microgravity by enhancing metabolite synthesis while maintaining a reduced virulence profile. Finally, these findings of fungal adaptation can give some insight for both space health management and industrial enzyme production in extraterrestrial environments.