| Arthrosporols are an unique group of small molecule compounds from Arthrobotrys oligospora that could regulate the formation of conidia and 2D networks.Metabolic study of mutant strains of this fungus have found that 10 genes were involved in the biosynthesis of arthrosporols.A series of intermediates involved in the biosynthesis of arthrosporols have been obtained from 7 mutant strains(ΔAOL_s00215g283,ΔAOL_s00215g282,ΔAOL_s00215g28,ΔAOL_s00215g280,ΔAOL_s00215g278,ΔAOL_s00215g276,and ΔAOL_s00215g274).Among these intermediates,17 compounds are novel and 3 compounds show nematicidal activity.In this study,mutant strain ΔAOL_s00215g279 was selected to study metabolites with high performance liquid chromatography(HPLC),thin layer chromatography(TLC)and nuclear magnetic resonance(NMR)spectroscopy.Key results and innovations:1.Bioinformatics analysis shows that ΔAOL_s00215g279 encodes an FAD-dependent oxidoreductase,which might be a secreted protein and locate in the endoplasmic reticulum,Golgi apparatus or lysosome.2.The mycelial morphology,mycelial growth,sporulation,3D network and nematode-capturing ability of the mutant strain ΔAOL_s00215g279 was studied.Our results showed that this mutant displayed denser mycelia but slower growth rate than WT.Mutant ΔAOL_s00215g279 showed significantly reduced spore production,only 0.6% of the wild strain.Mutant ΔAOL_s00Δ215g279 produced more traps and showed significant nematicidal activity,1.5 times more than WT within 6h of contact with nematodes.Although ΔAOL_s00215g279,the traps number of this mutant shows no difference with WT in later co-cultivate periods.3.Seven compounds were isolated from the ethyl acetate and n-butanol fractions of mutant ΔAOL_s00Δ215g279.Compounds DGG-1 and DGG-2 are novel compounds with new skeletons which consisting of a farnesyl chain with m-cresol;The other 5 compounds inclued ergosterol,cerebroside,tyrosol,pyrene,and alpha-ketoglutaric acid,which are important for fungal metabolism.This study showed that gene AOL_s00215g279 encodes an FAD-binding enzyme,which catalyzes hydroxy groups to ketone which is likely involved in the cell’s secretory pathway;its lack results in decrease in the mycelial growth,sporulation,but increase in 3D network and nematode-capturing ability.Novel class of farnesyl and m-cresol hybrids were obtained from mutantΔAOL_s00Δ215g279.Combined with studies on the synthetic pathway of arthrosporols,gene AOL_s00215g279 was speculated to be involved in the oxidation modification of critical intermediates. |
