| Purpureocillium lavendulum is a new species different from Pur.lilacinum derived from Purpureocillium.In recent years,the research and development of microbial resources to control plant pathogenic nematodes have received much attention.According to literatures,Purpureocillium is currently one of the most potential fungi for biological control of plant parasitic nematodes,while Pur.lavendulum,the biological control mechanism has good research,but there are few reports on secondary metabolites of Pur.lavendulum in biocontrol.In this dissertation,two strains of Pur.lavendulum YMF1.00683 and YMF1.00073 were used as the research objects.Based on the detection and analysis of LC-MS and TLC,the cultural conditions of Pur.lavendulum YMF1.00683 and YMF1.00073 are screened for producing abundant metabolites.After accumulating the secondary metabolites,the metabolites produced by Pur.lavendulum were separated and purified by traditional natural product chemical methods(thin layer chromatography,silica gel column adsorption chromatography,gel filtration layer by analytical method,HPLC).Those obtained compounds were identified by using the data of nuclear magnetic resonance spectroscopy,mass spectrometry and ultraviolet spectroscopy were combined with the database,and then were assayed the activity.The cultured conditions were screened for Pur.lavendulum YMF1.00683 and YMF1.00073,and the crude extracts were detected by analysis TLC and LC-MS,and SDA solid medium was selected for fermentation.Twelve compounds were isolated and identified from the fermentation product of Pur.lavendulum YMF1.00683,among which MPLB-13 is a new steroid,and the others were known compounds,including steroids,fatty acids,nucleotides,pyrroles.Ten compounds were identified from the fermentation product of Pur.lavendulum YMF1.00073,and all of them were known compounds including cyclic dipeptides,furans,amides and nucleotides.According to the structural characteristics of the compounds,the isolated and identified metabolites were assayed for the activities aganist Meloidogyne incognita.The results showed that the compound 5-(Methoxymethyl)-1H-pyrrole-2-carboxaldehyde(compound 7),isolated from Pur.lavendulum YMF1.00683,exhibited virulent activity against M.incognita at 400 μg/m L for 96 hours(corrected lethality reached 98.2%).At the concentration of 40 μg/m L,it can significantly inhibit the hatching activity of M.incognita eggs.After testing the chemotactic effect on M.incognita,the results showed that compound 7 exhibited a strong avoidance effect(C.I.=-0.38)on root-knot nematodes at the concentration of 40 μg/m L,but it showed a weak attraction effect(0<C.I.<0.2)at the concentration of 5 μg/m L.7,8-dimethylalloxazine(compound 6)also showed significantly inhibition hatching activity to M.incognita eggs at a concentration of 40 μg/m L.Ergosterol peroxid(compound 4)and 3β,5α,9α-Trihydroxy-ergosta-7,22-dien-6-one(compound 3)at the concentration of 400 μg/m L,it showed moderate virulent activity against M.incognita(corrected lethality rate reached 30%-50%)at 96 hours.Compounds5-Hydroxymethyl-furfural(compound 13)and 5-Hydroxymethylfuran-2-carboxylic acid(compound 22)isolated from Pur.lavendulum YMF1.00037 at a concentration of 400 μg/m L at 48 h for M.incognita moderate toxicic activity(corrected lethality rate of 30% to 70%).The compound Cyclo(L-Ala-L-Pro)(compound 16)at a concentration of 400 μg/m L,showed a good paralysis effect on M.incognita within12 hours,and at 18 hours,the paralysis effect was basically relieved.At the same time,the compound 16 showed a weak repelling effect on M.incognita at the concentration of 20 μg(C.I.=-0.3657).The compound Methyl indole-3-carboxylate(compound 19)exhibited a concentration-dependent attraction to M.incognita,and showed a strong attraction at 100 μg(C.I.= 0.29).According to the present results,Pur.lavendulum can produce metabolites with multiple activities against M.incognita. |
