一株具有抑菌活性的平榛内生真菌的鉴定

Identification of an endophytic fungus isolated from Corylusheterophyla Fisch with antibacterial activity

[目的]本研究对平榛内生真菌zs-14进行形态学及分子鉴定,并筛选其对不同供试菌株的抑菌活性。[方法]活化斜面试管保藏的内生真菌菌株zs-14,液体发酵培养3~5 d,采用液氮研磨法提取菌株zs-14的基因组DNA,应用PCR方法对内生真菌zs-14的ITS序列扩增,扩增产物经测序分析,同时结合菌落形态及乳酸-棉兰染色法的显微观察,最终鉴定内生真菌zs-14的种属;采用纸片扩散法筛选zs-14菌株的抑菌活性。[结果]zs-14菌株产生的分生孢子呈球形状,其菌落为毡毛状,菌落薄,皱缩,菌丝较致密,菌落中心呈浅绿色,最外层为白色。系统进化树结果显示其与Phoma sp聚为一类,因此鉴定内生真菌zs-14为茎点霉菌;纸片扩散法结果显示zs-14菌株发酵后只对金黄色葡萄球菌有抑制活性。[结论]平榛内生真菌zs-14具有产生抑菌活性物质的能力,研究结果可为下一步深入研究其抑菌代谢产物的种类提供科学依据。

[Objective]The present study was carried out to identify the endophytic fungus with morphological and molecular methods,and to determine its antibacterial activity against different bacterial strains.[Methods]The genomic DNA of the endophytic fungus zs-14 was extracted from liquid medium fermented for 3~5 days by liquid nitrogen grinding method.The ITS sequence was amplified by PCR,and the products were analyzed.The species of endophytic fungus zs-14 was identified by combining the colony morphology and the microscopic observation of lactic acid-cotton blue staining.The antimicrobial activity of strain zs-14 was screened by filter-paper diffusion method.[Results]The conidia produced by strain zs-14 were spherical shape,and the fungal colony was felt-hairy,thin and shrunken with dense hyphae.The center of the colony was light green color and the outermost layer was white.Phylogenetic tree analysis showed that it was clustered with Phoma sp.Therefore,endophytic fungus zs-14 was identified to belong to Phoma sp.Antibacterial activity study with filter paper diffusion method revealed that zs-14 strain possessed inhibitory activity against Staphylococcus aureus.[Conclusion]The endophytic fungus zs-14 isolated from C.heterophyla Fisch has the ability to produce antimicrobial active substances,which will provide scientific basis for further study of its antimicrobial metabolites.