来自红海榄根际土壤的曲霉属真菌F7菌株及其生物活性分析

基于菌落和菌体的形态特征以及ITS序列分析结果,将分离自中国海南省海口市东寨港红树林保护区红海榄根际土壤的菌株F7鉴定为曲霉属黄绿组的一种真菌。在确定和优化菌株F7培养基的基础上,初步确定了适合其分泌活性代谢产物的改良查氏培养基组成:3%乳糖,1%蛋白胨,0.3%NaNO3,0.05%KCl,0.05%MgSO4·7H2O,0.001%FeSO4,0.1%K2HPO4,pH7.0。将菌株F7接种于该培养基中,28℃下160r/min振荡培养7d后收获发酵液,经乙酸乙酯和正丁醇萃取后获得了乙酸乙酯萃取物(EAE)、正丁醇萃取物(BE)以及水萃取物(WSE),其中EAE和BE对金黄色葡萄球菌、藤黄八叠球菌和枯草芽孢杆菌的生长显示出明显的抑制活性,最低抑菌浓度(MIC)介于0.625-5.0mg/mL之间。同时,上述3种萃取物对人肝癌细胞株HepG2的增殖也表现出一定的抑制活性,IC50约为120μg/mL左右。

Aspergillus sp. strain F7 from the rhizospheric soil of Rhizophora stylosa and its biological activity evaluation

48 contaminative fungal isolates were obtained from wooden cultures of Tremella fuciformis which were collected from four different geographic origins. Morphologic identification showed that the 48 tested strains belonged to Annulohypoxylon and bore a resemblance to Annulohypoxylon annulatum. To affirm the taxonomic position of these isolates more precisely, ITS sequences of 14 tested strains were sequenced, and then subjected to phylogenetic analysis. The result showed that the resultant phylogenetic tree of the 14 tested strains consisted of two clades, was separated in the genetic distance of 0.036 and there was no obvious correlation between geographical distribution and genetic distance. The tested strains were confirmed as Annulohypoxylon, consistent with the morphologic identification. The genetic distance between the tested strains and Annulohypoxylon annulatum was around 0.2; whereas the genetic distance between the tested strains and an unknown cohabitant fungus of Tremella fuciformis was around 0.29. 75 ISSR primers were screened and 13 of them were selected to amplify the 48 tested strains and a total of 103 fragments were amplified, among them 72 (accounting for 69.9% of the total) were polymorphic. These 48 tested strains were divided into 5 groups under similarity of 75%, with no obvious correlation between geographical distribution and groups, by cluster analysis. The results showed that genetic similarity of these tested strains was low and there were obvious genetic variations in DNA level.