黄瓜内生放线菌的分离、筛选及其活性菌株鉴定

Endophytic actinomycetes of cucumber:isolation,antagonistic activity and identification

从植物内生放线菌中筛选拮抗活性菌株和寻找新的农用活性代谢产物,可为植物病害防治提供新的资源。本研究结果发现黄瓜幼苗的根、茎、叶中均有内生放线菌的存在,根组织中的数量、种类明显多于叶片和茎,占总分离株的72.7%,以链霉菌的淡紫灰类群、灰褐类群为主。活性筛选试验结果表明,黄瓜内生放线菌中对12种靶标真菌和6种细菌具有拮抗作用的菌株分别占46.8%和39.0%,主要为分离自根组织的链霉菌淡紫灰类群。分离自黄瓜叶片的gCLA4菌株抑菌谱较广,其发酵滤液对供试12种靶标真菌均具有较好的抑菌效果,但对靶标细菌有选择性抑制作用。形态学、细胞化学和16S rDNA序列分析鉴定该菌株为淡紫灰链霉菌(Streptomyces lavendularectus)。

The aim of the study is screening anti-microorganism endophytic actinomycetes for plant disease control. The results showed that 77 strains of endophytic actinomycetes were isolated from roots, stems and leaves of cucumber seedlings. Seventy two percent of endophytic actinomycete strains were isolated from roots, the quantity and variety of which were much higher than those from strems and leaves. Most of the isolates were Streptomyces （cluster： lavendularectus and griseofuscus）. Antagonistic activities of the endophytic actinomycetes against 12 pathogenic fungi and 6 bacteria strains were tested in vitro. The strains with antifungal and antibacterial activity were 46.8% and 39.0%, respectively, which were mainly isolated from roots and belonged to lavendularectus of Streptornyces. Furthermore, the cell-free filtrate of fermentation broth of strain gCLA4 isolated from leaves of cucumber seedling, showed notable inhibition effect on 12 pathogenic fungi and most tested bacteria strains. Identification of strain gCLA4 by morphological, cytochemical characters and 16S rDNA sequence showed it belonged to Streptornyces lavendularectus.