Influence of incubation time on metabolites in mycelia of Paecilomyces militaris

Abstract:

Abstract:［Objective］ To determine the secondary metabolites production in mycelia of Paecilomyces militaris．［Methods］Mycelia were cultured in plates with sabouraud dextrose agar yeast medium at 25℃ for 9 days． Sampling was done every day from the second to the ninth day． The secondary metabolites in the mycelia of Paecilomyces militaris were extracted with either methanol or ethyl acetate．The extracts were blended and analyzed by liquid chromatography-mass spectrometry (LC-MS)．LC-MS data were collected and analyzed by MetaboAnalyst software．［Result］ Principal component analysis indicates different secondary metabolites accumulation with incubation times． Hierarchical clustering analysis shows that the metabolic process of cationic compounds such as alkaloids，peptides and nucleosides can be divided into three stages，and that the metabolic process of anionic compounds such as organic acids and saccharides can be divided into two stages． Metabolites difference and heat map analysis show that:(1) The number of metabolites with significant increased contents was raised significantly in mycelia of Paecilomyces militaris on the second and third incubation days．The main species with increased contents were esters and their hydrolized products，destruxin B，variotin and some unidentified nitrogin contained compounds．(2) The number of metabolites with significant raised contents was decreased significantly on the fourth and fifth incubation days．The main species with increased contents were ophiocordin and destruxin A．(3) Apart from peptide antibiotics such as several beauverolides，the content increased metabolites included also several organic acids，amino acids，rhamnose，trehalose，cerebroside and riboflavine during the sixth to ninth incubation days．［Conclusion］ The secondary metabolites in mycelia of Paecilomyces militaris were related significantly to the incubation time.

Key words:Keywords: culture time，Paecilomyces militaris，mycelia，liquid chromatography-mass spectrometry，secondary metabolites