一株鱼腥草内生真菌的菌种鉴定及抑菌活性初探

目的 对鱼腥草内生真菌J3菌株进行菌种鉴定;研究J3菌株菌丝和发酵液粗提物的抑菌活性。方法 提取J3菌株基因组DNA,应用PCR技术获得ITS区扩增产物,经测序得到ITS序列,结合菌落形态、孢子形态对J3菌株进行鉴定;依次用乙酸乙酯和水饱和正丁醇分别对J3菌株菌丝和发酵液进行提取,并应用纸片扩散法研究粗提物对大肠埃希氏菌、铜绿假单胞菌、金黄色葡萄球菌和粪肠球菌的抑菌活性。结果 J3菌株的分生孢子为镰刀形;在系统进化树中J3菌株也与Fusarium oxysporum菌株聚在一类,因此结合形态学特征和ITS区序列,鉴定内生真菌J3菌株为尖孢镰刀菌;发酵液和菌丝的乙酸乙酯粗提物和水饱和正丁醇粗提物对粪肠球菌和金黄色葡萄球菌均有抑菌作用,但是对大肠埃希氏菌和铜绿假单胞菌无明显抑菌效果。结论 鱼腥草内生真菌J3菌株能够产生具有抑菌活性的代谢产物,值得进一步研究。

Identification and the antimicrobial activity of an endophytic fungus isolated from Houttuynia Cordata thunb

Objective To identify an endophytic fungus isolated from Houttuynia Cordata Thunb,and to study the antimicrobial activities of crude extracts from mycelia and fermented liquid. Methods The genomic DNA of strain J3 was extracted,and the PCR amplification of ITS region was sequenced.The strain J3 was identified according to colony morphology,spore morphology and ITS sequence.Crude extracts were derived from the mycelia and fermentation broths of liquid cultures with ethylacetate and water saturated n-butanol respectively.Filter-paper diffusion method was used to test the antimicrobial activity. Results The conidiospore of the strain J3 was sickle-shaped,and the phylogenetic analysis indicated strain J3 and Fusarium oxysporum strains formed a cluster.Based on morphological characteristics and ITS sequence,the strain J3 was identified as Fusarium oxysporum.All the crude extracts had antimicrobial activity against Staphylococcus aureus and Enterococcus faecalis.None showed influence on Escherichia coli and Pseudomonas aeruginosa. Conclusion The results indicate that the endophytic fungus isolated from Houttuynia Cordata Thunb is potential antimicrobial resource,which deserves further studies.