一株链霉菌21-1的分离鉴定及其对禾谷镰刀菌的抑菌活性

Streptomyces strain 21-1: isolation, identification, and activity against Fusarium graminearum

摘要:

【背景】由禾谷镰刀菌（Fusarium graminearum）引起的小麦赤霉病严重威胁我国的小麦生产。【目的】筛选对禾谷镰刀菌具有拮抗能力的链霉菌菌株，为生防菌剂开发提供理论基础。【方法】利用平板对峙法筛选对禾谷镰刀菌具有拮抗能力的链霉菌；通过形态特征、生理生化特征和16S rRNA基因序列分析对其进行鉴定；通过病原菌菌丝生长、孢子产生及萌发抑制试验分析其发酵液的抑菌活性；利用人工接种试验测定该菌株发酵液的防病效果。【结果】筛选到一株对禾谷镰刀菌具有较强拮抗活性的链霉菌21-1，抑菌率为59.5%。依据形态特征、生理生化特性和16S rRNA基因序列分析，将该菌株鉴定为黄三素链霉菌（Streptomyces flavotricini）。菌株21-1发酵液能够抑制禾谷镰刀菌的菌丝生长、孢子产生及萌发过程，而且可以降低禾谷镰刀菌菌丝中可溶性蛋白质的含量，并增加丙二醛的含量。菌株21-1可以产生蛋白酶及纤维素酶。菌株21-1菌液10倍稀释液对小麦赤霉病的防效最佳，为70.1%。此外，菌株21-1发酵液对其他8种植物病原菌均有较好的抑制作用。【结论】菌株21-1对禾谷镰刀菌有较好的抑菌活性，具有潜在的应用价值。

Abstract:

[Background] Fusarium head blight (FHB) caused by Fusarium graminearum has caused serious economic losses to the wheat industry in China.[Objective] To isolate and screen out the Streptomyces strains with inhibitory activity on F. graminearum and provide a theoretical basis for the development and application of biocontrol strains. [Methods]A plate confrontation experiment was conducted to screen out the strain with antagonistic effects on F. graminearum. The strain was identified based on morphological, physiological, and biochemical characteristics and sequence analysis of the 16S rRNA gene. The antagonistic activity of the fermentation broth was evaluated based on the mycelial growth, conidiation, and germination of F. graminearum. The biocontrol effect of the fermentation broth was evaluated by an artificial inoculation experiment. [Results] A Streptomyces strain 21-1 showed antagonistic effect on F. graminearum, with the inhibition rate of 59.5%, and it was identified as Streptomyces flavotricini. The fermentation broth of the strain inhibited the mycelial growth, conidiation, and germination of F. graminearum. Moreover, it decreased the content of soluble protein and increased the content of malondialdehyde in the mycelia of F. graminearum. Strain 21-1 had the ability to produce protease and cellulase. The control effect of the 10-fold diluted fermentation broth of the strain on FHB was 70.1%. In addition, the fermentation broth showed antagonistic activity against eight plant pathogens. [Conclusion] Strain 21-1 has a promising prospect in the biocontrol of F. graminearum.