Ergothioneine yield of Rhodotorula species 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 Rhodotorula strains were screened with hydrogen peroxide (H2O2) as the inhibitory condition. By measuring their carotenoid and EGT production and correlation analysis with H2O2 tolerance, the results showed that the carotenoid synthesis capacity has no effect on H2O2 tolerance, in contrast to a strong positive correlation between EGT yield and H2O2 tolerance of Rhodotorula species. In addition, a high EGT-producing strain R. mucilaginosa DL-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.