天山花楸内生真菌的分离及其抗菌活性物质的初步研究

Isolation and Antimicrobial Substances of Endophytic Fungi from Sorbus tianshanica Rupr.

采用组织块分离法从天山花楸茎、叶、果实中分离出17株内生真菌,分别运用对峙培养法和菌丝生长速率法进行初筛、复筛和抑菌活性试验,为抗菌活性菌株的应用以及抗菌物质的分离提纯奠定基础。结果表明:(1)菌株L18对棉花枯萎病菌和棉花黄萎病菌的抑菌作用较强。(2)形态学特征观察和rRNA ITS序列系统发育分析结果初步鉴定菌株L18为波兰青霉(Penicillium polonicum)。(3)该菌株发酵液中抑菌活性物质对温度较敏感,40℃处理后抑菌活性降低至对照的59.1%;对日光不稳定,而对紫外光较稳定;能被蛋白酶降解。(4)乙酸乙酯萃取该抑菌活性物质效果较佳,表明其极性较小,初步推测此活性物质属于蛋白质或肽类物质。

Seventeen strains of endophytic fungi were isolated from the stems, leaves and fruits of Sorbus tianshanica Rupr. ,their antimicrobial activities against two tested microorganisms were investigated by u- sing confront culture method and mycelium growth inhibition tests, The results showed that t （1）Endophyt- ic fungus L18 had strong antimicrobial activities to Fusarium oxysporum f, sp, and Verticillium dahliae Kleb, respectively. Strain L18 was identified as Penicillium polonicum by its morphological features and phylogenetic analysis based on internal transcribed spacer of rRNA sequence comparison. The antimicrobial substance of strain L18 in the fermentation broth was sensitive to high temperature. After 40 ℃ treatment, antimicrobial activity decreased to 59, 1 % of the control, It was more stable under ultraviolet than light. However,it could be degraded by proteases. The antimicrohial substance could be effectively extracted by ethyl acetate and indicated that it was low polar, Based on these results,we proposed that its antimicrobial substance may be proteins or peptides. The research revealed the basic features of strain L18 and might help to its further study and application,such as the isolation and purification of its antimicrobial substances.