Isolation and Identification of Soft Rot Disease Agent from Cultivated Mushrooms (Agaricus bisporus) in Türkiye

Abstract

Agaricus bisporus, a widely cultivated mushroom globally, is witnessing a rapid expansion of cultivation and consumption in Türkiye. In the Kadirli district of Osmaniye, Türkiye, instances of brown discoloration and soft rotting symptoms were observed on the caps of cultivated Agaricus bisporus. A total of 23 bacterial strains, including fluorescent varieties, were isolated from the affected portions. These strains exhibited morphological characteristics in line with the Pseudomonas genus. To pinpoint the potential causal agent of the disease, a range of techniques, including Gram reaction, oxidase activity, arginine dihydrolase, potato soft rot, levan production, hypersensitive reactions in tobacco, and microbial species identification through proteomic methods like Matrix Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry (MALDI-TOF/MS), were applied. Some strains from the mushrooms displayed a similar LOPAT profile characteristic of the reference strain Pseudomonas marginalis (GSPB 2325, Göttingen, Germany). This conclusion was further supported by pathogenicity tests and MALDI-TOF/MS analysis, with score values ranging from 1.781 to 2.094. To our knowledge, this marks the first report of soft rot disease caused by Pseudomonas marginalis in cultivated mushrooms in Türkiye.