Abstract
Background
The outer space is an extreme environment that has attracted continuous interest in microbial adaptation and safety, due to its high mutagenesis frequency and genetic variability. To date, several studies have assessed the impact of the space environment on the microbiomes and microorganisms. While the survival of Bacillus subtilis after spaceflight is well established, how the phenotype and metabolic function of B. subtilis respond to space stress is rarely reported.
Results
In this study, we performed a space flight of the B. subtilis TD7 strain facilitated by the launch project of the Xinyidai Zairen Feichuan-Shiyan Chuan, and compared the strains after spaceflight with the wild-type in terms of their growth, morphology, biofilm formation and secondary metabolism. The spaceflight strain exhibited slower growth, higher cell density, different morphology and decreased biofilm formation. Importantly, a decrease in the lipopeptide production was observed after spaceflight. Thus, we used a multi-omics approach to uncover the molecular mechanisms underlying the changeable secondary metabolism. A total of 14 gene clusters for secondary metabolite biosynthesis were identified in both the wild-type strain and spaceflight strains through whole-genome sequencing, including nonribosomal peptide synthetase. The comparative transcriptome revealed 997 differentially expressed genes which involved in the TCA cycle, fatty acid degradation, amino acid biosynthesis, and quorum sensing systems. The differential expression analysis of 26 lipopeptide-related DEGs further elucidated the relationship between the space environment and the regulation of secondary metabolism.
Conclusion
Our study is the first study to provide new insight into the behaviors, metabolic functions and adaptation mechanisms of B. subtilis in response to spaceflight. This knowledge could contribute to a better understanding of the relationship between the space environment and microbial adaption mechanisms.