Isolation and evaluation of Bacillus amyloliquefaciens Rdx5 as a potential biocontrol agent against Magnaporthe oryzae

Rice blast is one of the most serious rice diseases. It is caused by Magnaporthe oryzae resulting in rice shortages. Biological control has become a new measure in the control of plant diseases. In this study, we isolated antagonistic bacteria from the traditional Chinese medicinal plant Baizhi (Angelica dahurica) against M. oryzae. Biochemical, physiological and 16S rDNA sequence analysis proved that it was Bacillus amyloliquefaciens and we named the strain Rdx5. The experiment proved that Rdx5 can produce cellulase, protease, indole-3-acetic acid and 1-amino-cyclopropane-1-carboxylate deaminase. The sterilized culture filtrate of Rdx5 had strong antifungal activity after treatment at 100 °C for 30 min. In addition, its antifungal activity did not change in strong acid, neutral and weak alkaline environment. However, under strong alkaline conditions, the antifungal activity decreased significantly. In vitro and in vivo experiments showed that Rdx5 could prevent and treat rice blast, since the prevention group performed better than the treatment group. B. amyloliquefaciens Rdx5 might provide an alternative resource for the biocontrol of rice blast.