| High performance liquid chromatography mass spectrometry and metabolomics researchmethods were used to study metabolites of Paecilomyces militaris strain RCEF4733collected from huangshan, Anhui province. The studies focus on secondary metabolitesanalysis and comparison of mycelia at different culture time, treated with differentconcentration of oxidants, treated with different time of UV irradiation, and subculturedunder ordinary and dark light conditions.Different culture time analysis revealed that secondary metabolites of the mycelia ofRCEF4733were significantly changed during the process of incubation on SDAY medium.Metabolites change depending on the incubation time can be divided into prophase andanaphase.The prophase was from the culture starting to the fifth day. In this period, thestrain manly produced hydrolyzed and oxidated products which plays an important role ininfecting and colonizing on the host. The result suggested that culture of this period canincrease the rate of infection in biological control. Form the sixth day to the end of theincubation was the anaphase. In this period the starin mainly produce the oxidated productsof carbohydrate and its derivatives, which can be speculated that the enzymes ofcarbohydrate metabolism in the mycelium are more active，and that the fungi can rapidlyexhaust hepatin in insect and weaken metabolite and immunoreaction of the insect. Fromabove analysis we can conclude that during the process of cultue Paecilomyces militarisuse lipids primarily and then use carbohydrates. This process is consistent with theinfecting process of the fungi.Influence on secondary metabolites of the fungi RCEF4733treated with differentconcentrations of oxidant stress was analysed and the results showed that the compoundswere no significant difference at the same treating concentration. As the concentrationincreased, the metabolites were different significantly. When the oxidant concentrationreached to0.05ml/100ml the tested samples were divided into left and right parts in thescores plot, indicating that this concentration affected the synthesis of metabolitessignificantly. Ms analysis under the positive and negative mode we found that the type ofcompounds were nucleoside, ketones, esters and amino acids and their analogues,glycerides, unsaturated fatty acids, sugars,mannitol and so on. The unidentified compoundswere small peptide based on its retention time and unsaturation. The research found alsothat the relative content of stearic acid decreased, oleic acid and palmitic acid increased gradually when the oxidant concentration gradually increased, which can initially speculatethat unsaturated fatty acid was synthesized with saturated fatty acid by related enzymes.The presence of certain concentrations of oxidants can increase desaturation of thesaturated fatty acids.The process could protect the strain and provide energy for its lifeactivities.Secondary metabolites analysis results of the fungi treated with different time of UVirradiation showed that lipids, amino acids, saturated fatty acids, sterols and carbohydrateswere changed after irradidated. Short time UV irradiation time (10s and20s) had nosignificant effect on metabolites. Longer time UV irradiation can stimulate somecompounds synthesize. Component analysis showed that the concentration of glutamateand an unidentified compound was increased significantly.Metabolites studies of the subculture of the strain RCEF4733found that there were nosignificant difference within the first three generations, but there were significantmetabolites difference from the forth generation. The different metabolites includedunsaturated fatty acids, phospholipids, esters and sterols. Metabolites analysis of themycelia subcultured under different light conditions showed that the mycelia culturedunder dark condition had more metabolites difference than that of the mycelia cultured onmormal culture conditions. This mean that change of light condition during subculture canaccelerate metabolites variation. |
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