Isolation, identification and characterization of an antagonistic bacterium against Bipolaris papendorfii

Abstract:

[Background] Bipolaris papendorfii is the main fungal pathogen of Curvularia leaf spot, and harmful to agricultural production. At present, the use of bacteria to control B. papendorfii becomes research focus in this field. [Objective] To screen the strains with high antagonistic activity against B. papendorfii, and identify the antagonistic mechanism. [Methods] Twenty-two bacterial strains were isolated from the soil under the surface of corn field by the method of plate confrontation. One strain L-14 with high antagonistic activity to B. papendorfii was obtained by repeated screening. [Results] Strain L-14 with the highest antagonism was obtained by using the plate diffusion method. After morphological observation, 16S rRNA gene sequence analysis, physiological and biochemical characteristics detection, the strain was finally identified as Bacillus subtilis. Moreover, the strain is a wide-spectrum antagonistic biocontrol strain with inhibitory effects on Fusarium proliferatum, Fusarium graminearum, Exserohilum turcicum, Bipolaris papendorfii and Botrytis cinerea. Then, we studied the antibacterial mechanism of strain L-14 and obtained that the fermentation crude protein extracts had no effect on the morphology of the aerial hyphae of B. papendorfii but can cause the mycelial aberration, and had an inhibitory effect on spore germination. [Conclusion] The antagonistic bacterium B. subtilis obtained in this study has broad spectrum and high antagonistic activity in the control of plant diseases, and can effectively control Curvularia leaf spot.

Key words:Bipolaris papendorfii, Isolation, Screening, Identification, Bacillus subtilis, Antagonism