Evaluation of the efficacy of endophytic Bacillus amyloliquefaciens against Botryosphaeria dothidea and other phytopathogenic microorganisms

Endophytic bacteria were isolated from poplar trees in Shandong province, China, where canker disease caused by Botryosphaeria dothidea has reached epidemic proportions. On the basis of the results of classical bacteriological tests and sequence analysis of the 16S rRNA gene, the PEBA20 strain isolated from poplar was identified as a strain of Bacillus amyloliquefaciens. In vitro PEBA20 inhibited the mycelium growth of B. dothidea and canker disease incidence on the cut shoots of poplar 60% than that in the control 100%. The optimum culture conditions for the propagation of the antagonistic strain against B. dothidea were determined using an orthogonal experiment design. The strain showed antifungal and antibacterial activity against a number of microorganisms, including mycelial fungi, yeast, gram-positive and gram-negative bacteria. TasA and aiiA-2 genes associated with antagonistic activity were detected in PEBA20. The results of our study indicate that B. amyloliquefaciens PEBA20 has the potential to serve as a biological control agent for the poplar canker disease caused by B. dothidea and for diseases caused by other phytopathogens.