光枝勾儿茶内生真菌多样性及抑菌活性研究

Diversity and antibacterial activity of endophytic fungi from Miao medicine Berchemia polyphylla var. leioclada

关键词:  光枝勾儿茶, 内生真菌, 多样性, 候选菌株, 抑菌活性

Key words:  Berchemia polyphylla var. leioclada, endophytic fungi, diversity, candidate strains, antibacterial activity

摘要:

为探索贵州苗药光枝勾儿茶内生真菌类群特征、分布部位及其抑菌活性,该研究采用传统方法对贵州省贵阳市和黔西市光枝勾儿茶内生真菌进行分离,并基于分子生物学及统计学对其分类地位进行鉴定及多样性评价,最后通过微量肉汤倍比稀释法筛选具有抑菌活性的菌株。结果表明:(1)从光枝勾儿茶中分离到191 株内生真菌,隶属于3 个门5 个纲10 个目15 个科19 个属,优势属为叶点霉属(Phyllosticta)、间座壳属(Diaporthe)、葡萄座腔菌属(Botryosphaeria)和刺盘孢属(Colletotrichum)。(2)黔西光枝勾儿茶内生真菌香农-维纳多样性指数(H'_Q=2.112)较贵阳(H'_G=1.801)高,索伦森相似性指数Cs_G-Q为0.923,不同组织香农-维纳多样性指数为茎(H'_S=2.004)>根(H'_R=1.764)>叶(H'_L=1.654)>果实(H'_F=1.473),茎和叶内生真菌的索伦森相似性最高(Cs_S-L=0.667)。(3)筛选出的21株内生真菌对供试菌大肠杆菌(Escherichia coli)、金黄色葡萄球菌(Staphylococcus aureus)和沙门氏菌(Salmonella enterica)具有抑菌效果,其中Diaporthe sp. QX4G6对大肠杆菌、金黄色葡萄球菌和沙门氏菌的最小抑菌浓度分别为12.5、6.25、12.5 mg·mL^-1,最小杀菌浓度分别为12.5、6.25、12.5 mg·mL^-1。以上研究结果揭示了光枝勾儿茶蕴藏丰富的内生真菌资源,不同地区及组织内生真菌类群组成有差异,多个分离菌株具有抗菌活性,为光枝勾儿茶内生真菌天然抗菌药物或药源研发奠定了基础。

Abstract:

To explore the fungal taxa, distribution and antibacterial activity of Berchemia polyphylla var. leioclada, endophytic fungi of B. polyphylla var. leioclada from Guiyang and Qianxi of Guizhou Province were isolated by tissue fragment separation. Based on the methods of molecular biology and statistics, the endophytic fungi were identificated and their diversity were analyzed. The strains with antibacterial activity were screened by microdilution of broth. The results were as follows:(1)There were 191 fungal strains were isolated, which classified into 3 phyla, 5 classes, 10 orders, 15 families and 19 genera. Among all strains, Phyllosticta, Diaporthe, Botryosphaeria and Colletotrichum were the dominant genus.(2)The fungal endophytes' Shannon-Weiner diversity index of Berchemia polyphylla var. leioclada in Qianxi(H'_Q=2.112)was higher than Guiyang(H'_G=1.801), the Sorenson's similarity coefficient(Cs_G-Q)was 0.923. The Shannon-Weiner diversity index of different tissues was stem(H'_S =2.004)> root(H'_R=1.764)> leaf(H'_L=1.654)>fruit(H'_F=1.473). The similarity index between stem and leaf was the highest which was Cs_S-L =0.667.(3)21 endophytic fungi' secondary metabolites had inhibitory effect on Escherichia coli, Staphylococcus aureus and Salmonella enterica. The isolate Diaporthe sp. QX4G6 fermentation broth extract have relatively high inhibitory effect, which the minimum inhibitory concentration against Escherichia coli, Staphylococcus aureus and Salmonella enterica were 12.5, 6.25 and 12.5 mg·mL^-1, and the minimum bactericidal concentration were 12.5, 6.25 and 12.5 mg·mL^-1, respectively. The study reveal rich endophytic fungi resources of Berchemia polyphylla var. leioclada and most of fungi have good antibacterial activity, which lay the foundation for the research and development of natural antibacterial drugs or drug sources for endophytic fungi from B. polyphylla var. leioclada.