Secondary Metabolites Of Colletotrichum Scovillei And Their Antibacterial Activities

With the in-depth exploration of microbial secondary metabolites,it is more difficult to find new metabolites from common microbial resources.In order to obtain new metabolites with good activity,more effective new strategies are needed.Plant pathogenic fungi have attracted much attention because of their special living style and metabolic pathway,producing special and potential metabolites.The strain LJ17091309-02,which was isolated from pepper fruit with anthracnose,was identified as Colletotrichum Scoville.The crude extract of 3.4 g was isolated and extracted from the fermentation broth of the strain by constant temperature oscillation culture,macroporous resin（XAD-16）adsorption and methanol soaking.Two compounds were isolated and their structures were identified by chromatographic and spectroscopic methods.Compound 1 is a new compound,which has not been reported and identified as ceramide.Compound 2 is a known compound sambutoxin,which is an alkaloid compound with the chemical name of 3-{5-methyl-6-[（E）-1,3,5-trimethylhept-1-enyl]Tetrahydropyranyl}-5-（p-hydroxyphenyl）-1-menthyl1-4-hydroxy-2（1H）-pyridone.The antibacterial activities of the two compounds were determined by 96 well plate microdilution method,mycelial growth rate method and in vitro leaf method.The results showed that compound 1 had antibacterial activity against Magnaporthe oryzae,Rhizoctonia solani and Exserohilum turcicum,and compound 2 was against Fusarium graminearum and Rhizoctonia Solani,Bipolaris sorokkiniana and Exserohilum turcicum had antibacterial activities.The two compounds had the highest antibacterial activity against Exserohilum turcicum.The results showed that the EC₅₀ value of compound 1 against Exserohilum turcicum was 11.43μg/ml,and that of compound 2 against Exserohilum turcicum was 18.42μg/ml.The results of in vitro leaf assay showed that at the concentration of 800μg/ml,the two compounds and chlorothalonil（positive control）had significant effects on Exserohilum turcicum.The control effects were 84.8%,79.3%and 88.9%,respectively.When the concentration of 400μg/ml,the control effects were 76.3%,69.8%and 82.7%,respectively.Chlorothalonil（positive control）had better control effect,and the two compounds also showed certain antibacterial activities,which indicated that the two compounds had the potential to become pesticide lead compounds.