The sustainability and productivity of agriculture can be significantly enhanced through the use of Plant Growth Promoting Microorganisms (PGPM). Trichoderma species are well-known Plant Growth Promoting Fungi (PGPF) with proven capabilities in promoting plant growth, and they have been studied for many years as soil microorganisms. The utilization of Trichoderma species in sustainable agricultural systems can potentially to increase soil fertility, thereby contributing to environmentally friendly farming practices. In this study, Trichoderma strains (n=62) isolated from various soil and fungal compost samples were investigated for their PGPM properties. These properties include antagonistic effects against phytopathogens, lytic enzyme activities, siderophore and IAA production, phosphate solubilization, and potassium mobilization. Three Trichoderma isolates showing high PGPF activity were identified, and their molecular characterization was conducted. Two isolates of Trichoderma koningiopsis and one isolate of T. harzianum were identified.

During the cultivation of button mushrooms, the green mold epidemic, which causes a decrease in productivity, is a very important problem. The environmental harm of chemicals used in the control of such epidemics and the demand of consumers for organic products without chemicals have brought environmentally friendly biological control to the fore. Biological control can be achieved by the use of antagonistic microorganisms and their metabolites. In this study, the effectiveness of Bacillus and Pseudomonas spp. for the biological control of the green mold disease agent Trichoderma aggressivum subsp. in Agaricus bisporus cultivation was examined. For this purpose, the antifungal effects of Bacillus and Pseudomonas spp. against T. aggressivum strains were examined by an in vitro dual culture test and the agar well diffusion method. Then, it was determined whether the bacterial strains showing antifungal activity showed antagonistic activity against A. bisporus. Although none of the Pseudomonas spp. showed antifungal activity against T. aggressivum strains, most of the Bacillus spp. were found to have high activity. It has been concluded that Bacillus sp. Ö-4-82, which shows high antifungal activity against T. aggressivum subsp. and low antagonism against A. bisporus, may be potential biological control agents for button mushroom cultivation.