Cell cycle arrest mitigates the loss of ribonucleic acid content in Saccharomyces pastorianus

Numerous studies have developed various methods to increase RNA content in yeast cells. However, the reduction of RNA content during the late growth stage appears to be unavoidable. In this study, we examined the relationship between cell cycle progression and RNA content, the trend of G2 phase cells was consistent with the RNA content. To investigate the impact of G2 arrest on RNA synthesis, we evaluated the performance of G03H8 cells by overexpressing CHK1, CKI1, or CAJ1. Finally, the RNA production was increased through the high-density fermentation of engineered strain. The results demonstrated that all three genes mitigated the reduction of RNA content during the late growth stage, with CHK1 having a minimal adverse effect on biomass reduction. In H8-CHK1 cells, the proportion of cells in the G2 phase initially decreased slightly before increasing again. A similar effect was observed when CHK1 was overexpressed in G03-△PRS5, which exhibited a higher RNA content than G03H8. To address the growth reduction associated with G2 arrest, we achieved a dry cell weight of 45.79 g/L and the final RNA production of 4.94 g/L in H8-CHK1, which had increased by 37.9% compared to fed-batch fermentation of G03H8. This study provides valuable insights into the mechanisms of RNA synthesis and offers novel strategies for enhancing RNA production in yeast cells.