XVI International Botanical Congess

Gram-positive bacteria having potential to reduce the level of extracellular toxins (i.e., tolaasins) produced by Pseudomonas tolaasii, the most destructive pathogen of cultivated mushrooms, were consistently detected in both cultivated and wild Pleurotus ostreatus fruiting bodies. Inoculation of the isolated bacteria prevented the development of bacterial disease in P. ostreatus and Agaricus bisporus in our laboratory tests. From fruiting bodies of other Agaricales fungi in the field, various bacteria that detoxify tolaasins were also isolated, such as Acinetobacter sp. with a close similarity to A. baumannii from Tricholoma matsutake, Bacillus pumilus from Coprinus disseminatus, Sphingobacterium sp. with close similarity to S. heparinum from Clitocybe sp., and Sphingobacterium multivorum from C. clavipes. Some of these bacteria may be useful in future for developing a biocontrol system of cultivated mushrooms.