Screening of carbon and nitrogen sources suitable for the growth of Epichloë sinensis

Early screening for characteristics associated with superior Epichloë sinensis endophytic fungal strains that may be suitable for further screening has been growing rapidly. However, it is not clear which are the best carbon and nitrogen sources for E. sinensis growth. Therefore, this study investigated different carbon sources (glucose, starch, maltose, mannitol, sorbitol) and nitrogen sources (ammonium chloride, peptone, tryptone, yeast powder, urea). Three E. sinensis strains (strain ID: 1, 41C, and 111C) were cultured on solid or liquid media to explore the growth status and total antioxidant capacity of E. sinensis when supplied with different carbon and nitrogen sources. The results showed that the colony diameter, colony growth rate, mycelium biomass, and the total antioxidant capacity of strain 111C were significantly higher than those of strains 1 and 41C (P < 0.05), while the mycelium diameter of 111C was lower than that for 1 and 41C. The correlations among the mycelial diameter, mycelium biomass, and colony diameter of the three E. sinensis strains were different. Correlations among the three indexes for strain 111C were the highest, strain 41C was second, and strain 1 was the lowest. The most suitable carbon and nitrogen sources for the different strains were also different. Among the five carbon and nitrogen sources tested, the best carbon and nitrogen sources for strain 111C were maltose and tryptone, respectively; the best for strain 41C were glucose and tryptone, respectively; and the best sources for strain 1 were glucose and tryptone, respectively. The total antioxidant capacity of the three endophytes was highest when yeast extract powder was used as the nitrogen source. In this study, the superior strain 111C was selected for subsequent development and utilization, and the optimal carbon and nitrogen source for the growth of E. sinensis endophytes was preliminarily studied.