Study On Antimicrobial Metabolites Of Intestinal Penicillium Mallochii In Ectropis Oblique

Endophytic microorganisms in the gut of insects are special microbial species,which are important resource of new active metabolites.In this paper,the antimicrobial active components of intestinal fungus of Ectropis oblique are studied.The main results are as follows:1.An endophytic fungus CCH01 was isolated from the gut of Ectropis oblique.The fungus was identified as Penicillium mallochii by morphological and molecular biological characteristics.Five compounds,including mannitol?1?,ergosterol?2?,penoxide B?3?,isochromophilone IV?4?,sclerotioramine?5?,sclerotiorin?6?were isolated and purified from the secondary metabolites of the strain by silica gel chromatography,gel column chromatography,sephadex LH-20 and recrystallization.2.The metabolites of the fungus were analyzed by changing the difference culture conditions.The results showed that the secondary metabolites of the strain cultured in malt medium were more abundant than those in potato medium,and the secondary metabolites in solid fermentation were more abundant than those in liquid fermentation.3.The fungus was treated by plasma mutagenesis.It was found that the amount of secondary metabolites after 120 s mutagenesis was higher than that of the control group.In addition,the fungus was also exposed to the mutagens of different drugs?nicotinamide 5-azazosporin,volenotta,valproic acid?.Two new structural compounds SAHA-X₁?7?and SAHA-X₂?8?were obtained from the fungus.4.The antimicrobial activity of the secondary metabolites of fungus was tested by the methods of growth rate and agar disc diffusion.Isochromophilone IV?4?showed great activity against the growth of Curvularia clavata;Sclerotioramine?5?exhibited potent activity against the growth of Colletotrichum graminicola with IC₅₀0 of 1.78?g/ml;?+?Sclerotiorin?6?showd good activity against the growth ofC.clavata,Fusarium oxysporum f.sp.momordicae and Botryosphaeria dothidea with the IC₅₀values of 2.10?g/ml,4.04?g/ml,2.78?g/ml,respectively.When the concentration was 30?g/filter paper,compounds 5 and 6 showed moderate activity against the growth of Staphylococcus aureus,the diameter of inhibition circle was between 4.00-9.50 mm;The new compound SAHA-X₂?8?showed potent activity against the growth of Candida albicans with the inhibition zone of 10.5 mm,and a very weak activity against the growth of Escherichia coli and Staphylococcus aureus with the inhibition zone of 2.95 mm and 3.00 mm,respectively.