Abstract
Brown blotch is a serious bacterial disease affecting mushroom production. The causal agent, Pseudomonas tolaasii, secretes tolaasins, lipodepsipeptide toxins that cause browning of fruiting bodies in a broad range of mushrooms. In this study, to develop biological control agents for bacterial brown blotch on mushrooms, we evaluated the bacterial flora of shiitake fruiting bodies and isolated tolaasin detoxifying bacteria. The culturable flora on fruiting bodies of shiitake consisted of various bacteria, and were stable during shiitake cultivation. Tolaasin detoxifying bacteria, consisting of Bacillus sp., Leifsonia sp., Microbacterium sp., Paenibacillus sp., Plantibacter sp., Pseudoxanthomonas sp., Sphingobacterium sp., and Streptomyces sp., were isolated from shiitake fruiting bodies. Analysis of the mechanism of tolaasin detoxification by Pseudoxanthomonas spp. suggested that tolaasin detoxifying ability is widely distributed in Pseudoxanthomonas spp.
