Screening of endofungal bacteria isolated from wild growing mushrooms as potential biological control agents against brown blotch and internal stipe necrosis diseases of Agaricus bisporus

Brown blotch and internal stipe necrosis caused by Pseudomonas tolaasii and Ewingella americana, respectively are two important diseases of cultivated mushroom. The aim of the present study was to evaluate antagonistic activity of endofungal bacteria isolated from wild growing mushrooms against Pseudomonas tolaasii and Ewingella americana. Both pathogens were isolated from infected cultivable button mushrooms and characterized by phylogenetic analysis. A total of sixty-six endofungal bacteria were isolated from wild growing mushrooms at various locations of Kurdistan Province. Based on preliminary phenotypic properties, eleven selected isolates were further characterized. 16 s rRNA gene-based phylogenetic analysis revealed that these isolates had 99-100% similarity to Pseudomonas, Bacillus, Serretia, Stenotrophomonas and Brochothrix genera. The results of protease, lipase and siderophore production were varied amongst isolates tested. Under in vivo conditions, Bi1 strain with 96.7% reduction of brown blotch symptoms and De4 strain with 72.25% reduction of internal stipe necrosis symptom had the highest antagonistic activity against P. tolaasii and E. americana, respectively. To the best of our knowledge, this is the first report of the isolation of endofungal bacteria from wild-growing mushrooms with biological control activity.