Enhanced Ribonucleic Acid Production by High-Throughput Screening Based on Fluorescence Activation and...

Currently, the primary source of ribonucleic acids (RNAs), which is used as a flavor enhancer and nutritional supplement in the food manufacturing and processing industries, for large-scale industrial production is yeast, where the challenge is to optimize the cellular RNA content. Here, we developed and screened yeast strains yielding abundant RNAs via various methods. The novel Saccharomyces cerevisiae strain H1 with a 45.1% higher cellular RNA content than its FX-2 parent was successfully generated. Comparative transcriptomic analysis elucidated the molecular mechanisms underlying RNA accumulation in H1. Upregulation of genes encoding the hexose monophosphate and sulfur-containing amino acid biosynthesis pathways promoted RNA accumulation in the yeast, particularly in the presence of glucose as the sole carbon source. Feeding methionine into the bioreactor resulted in 145.2 mg/g dry cell weight and 9.6 g/L of cellular RNA content, which is the highest volumetric productivity of RNAs achieved in S. cerevisiae. This strategy of breeding S. cerevisiae strain with a higher capacity of accumulating abundant RNAs did not employ any genetic modification and thus will be favored by the food industry.