Effect of sodium selenite concentration and culture time on extracellular and intracellular metabolite profiles of Epichloë sp. isolated from Festuca sinensis in liquid culture

Abstract Selenium (Se) is a member of trace elements which are critical for proper functioning of an organism, and is one of the abiotic stressors which affect living organisms growth and metabolite. In this study, Epichloë sp. from Festuca sinensis was submitted to increasing Na2SeO3 concentrations (0, 0.1, and 0.2 mmol/L) in the liquid media for 8 weeks. Epichloë sp. mycelia and fermentation broth were collected by centrifuging at 4, 5, 6, 7, 8 weeks of cultivation, respectively. About 157 and 198 metabolites were respectively determined in fermentation broth and mycelia using gas chromatography-mass spectrometer (GC-MS) analysis. Diverse changes in extracellular and intracellular metabolites were observed as Epichloë sp. exposured to selenite conditions and cultivation time. Eight common contributed metabolites (alanine, valine, isoleucine, glycine, serine, aminomalonic acid, 4-aminobutyric acid, and phenylalanine) were determined in fermentation broth and mycelia using principal component analysis (PCA). Some metabolites had highly accumulated in fermentation broth while others decreased after different time of exposure to Se as compared to the control media. However some metabolites were presented at lower concentrations in mycelia cultivated at selenite concentrations. These metabolites changed were involved in amino acids, carbohydrates, organic acids, fatty acids, and nucleotides under Se conditions, as well as ones over time. Based on these results, we conclude that selenite concentrations and culture time influenced the extracellular and intracellular metabolite profiles of Epichloë sp. from F. sinensis.