Indigenous Bacterial Endophytes as Sustainable Alternatives for Management of Green Mould Disease in Agaricus bisporus

Trichoderma aggressivum f. aggressivum is a major pathogen responsible for the green mould disease in Agaricus bisporus, causing significant yield losses. This study evaluated the effects of native bacterial strains as biocontrol agents against T. aggressivum f. aggressivum in the cultivation of Agaricus bisporus. Bacterial strains were collected from mushroom caps and screened for plant growth-promoting traits, including siderophore production, phosphate solubilisation, indole-3-acetic acid synthesis, chitinolytic, and proteolytic activities. In vitro antagonism assays identified Pseudomonas chlororaphis (Pl 4/2), Bacillus wiedmannii (Pl 6/1), and Bacillus cereus (Pl 5/2) as the most promising candidates. In vivo assays under controlled compost conditions revealed that Pl 5/2 significantly enhanced mycelial growth in A. bisporus. Field trials have confirmed its strong biocontrol potential, with disease severity reductions comparable to the fungicide Prochloraz. Furthermore, Pl 5/2 markedly increased the mushroom yield and the improved cap number and weight in A. bisporus. These results demonstrate the dual functionality of B. cereus Pl 5/2 in suppressing green mould and promoting yield, supporting its potential integration into sustainable, chemical-free mushroom production systems.