Abstract:[Background] Recent studies have found that microgravity conditions can affect the proliferation and toxicity of some pathogenic microorganisms. Candida albicans is a typical conditional pathogenic fungus, which is ubiquitous in space environment and human body. It is of great significance to study the proliferation and toxicity of C. albicans under microgravity conditions. [Objective] Rotating cell culture system (RCCS) was used to simulate the microgravity environment for continuous subculture of C. albicans. The changes of proliferation, toxicity and gene expression of C. albicans in simulated microgravity environment were detected. [Methods] C. albicans were inoculated in high aspect rotating vessel (HARV) and cultured in RCCS for 14 days. After the culture completed, the proliferation rates of C. albicans were measured. The proliferation abilities were detected under different pH conditions, and the cytotoxicity and animal toxicity were determined. The differentially expressed genes were identified by RNA-seq. [Results] In the simulated microgravity group, the logarithmic phase of C. albicans was earlier and the proliferation rate was faster, the proliferation ability was generally improved under suitable pH conditions, but its relative biolfilm formation and toxicity to LoVo cells and mice was weakened. RNA-seq revealed that 280 genes expressed differentially more than 1.5 times (P<0.05), of which 248 were up-regulated and 32 were down-regulated in simulated microgravity environment. The differential genes were enriched by GO and KEGG, and the gene expressions of cell membrane formation and cell division were up-regulated in simulated microgravity environment , while the gene expressions of biofilm, cell adhesion and symbiotic adhesion host were down-regulated. [Conclusion] Simulated microgravity environment can change the proliferation and toxicity of C. albicans, and the related changes can provide reference for studying on the influence of microgravity environment on microorganisms.
