Ergothioneine yield of Rhodotorulaspecies positively correlated with hydrogen peroxide tolerance

Ergothioneine (EGT) is a natural sulfur-containing amino acid with potent antioxidant and cytoprotective activities. In this study, the oxidation tolerance of 23 different Rhodotorulastrains were screened with hydrogen peroxide (H2O2) as the inhibitory condition. By measuring their carotenoid and EGT production and correlation analysis with H2O2tolerance, the results showed that the carotenoid synthesis capacity has no effect on H2O2tolerance, in contrast to a strong positive correlation between EGT yield and H2O2tolerance of Rhodotorulaspecies. In addition, a high EGT-producing strain R. mucilaginosaDL-X01 was screened with the yield of 38.48 ± 2.71 mg/L in a shaking flask fermentation. To the best of our knowledge, this is the highest EGT yield ever reported in non-recombinant strains. Growth kinetic data showed that DL-X01 had a longer lag phase in the presence of exogenous oxidant, but a shorter generation time and higher specific growth rate after entering the exponential phase. The results of this study provided a potential simple and rapid method for screening high EGT-producing strains, which could promote the efficient production of EGT by microorganisms and further development of the red yeast in the food and biotechnology industries.