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

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.