Bean root rot (Fusarium solani) is an important disease in major areas of bean production in the world, including Iran, which causes significant damage to bean crops every year. To date, various methods have been used to control this fungus, including physical and chemical controls; however, due to the multiplicity of host and soil fungus, the use of biological control seems to be a suitable alternative and an important tool for managing this disease. A number of biological control methods have been implemented using endophytic bacteria, which have been effective in controlling and reducing this disease. In this study, the inhibitory effect of Pseudomonas fluorescens and Bacillus subtilis against bean root rot fungus, which were isolated from the root and crown of the bean plant using endophytic bacteria, was investigated in vitro. This experiment was performed with the help of cross-culture test, study of antifungal volatile compounds, extracellular material production test and antibiotic production. The studied bacteria were isolated and purified from bean fields in Lorestan province and were identified based on standard bacteriological tests and using PCR method and specific primers of 16S rRNA gene. In cross-culture test, Pseudomonas fluorescens and Bacillus subtilis isolates showed inhibition above 52% and 55%, respectively. In the production of antifungal volatile compounds, Pseudomonas fluorescens and Bacillus subtilis showed 27% and 29% inhibition, respectively. In the antibiotic production test, both isolates controlled up to 90% of the growth of the pathogenic fungus by producing high amounts of antibiotics. Pseudomonas fluorescens and Bacillus subtilis isolates were also effective in controlling the disease fungus by 29% and 36%, respectively. According to the results of laboratory tests, these isolates can be introduced as a biocontrol agent against Fusarium solani.
