The mechanisms of Wickhamomyces anomalus in control of postharvest black spot disease in tomatoes and the preparation of its biocontrol solid products

Postharvest black spot of tomato causes considerable economic losses to the tomato industry. Biological control presents a sustainable and efficient alternative. This study investigated the biocontrol mechanism of Wickhamomyces anomalus and optimized its lyoprotectant formulation using response surface methodology. Results revealed that W. anomalus effectively antagonizes Alternaria alternata by colonizing tomato tissues and inhibiting spore germination and hyphal growth in vitro . Response surface analysis identified the optimal lyoprotectant formulation as follows: sorbitol (6.44 g/100mL), skimmed milk powder (10.49 g/100mL), L-glutamine sodium (3.18 g/100mL), and trehalose (4.94 g/100mL). Under this formulation, the survival rate of lyophilized W. anomalus was 85.9 %. Notably, the formulation maintained high storage stability, with a survival rate of 67.0 % after 90 days. During storage, the biocontrol efficacy against black spot remained robust–the rot rate of W. anomalus -treated tomatoes only increased from 14.1 % to 24.0 %, demonstrating its persistent biocontrol activity. In conclusion, an efficient and stable biocontrol agent based on W. anomalus has been developed, offering a promising solution for controlling postharvest diseases in tomatoes. • Wickhamomyces anomalus antagonizes Alternaria alternata by colonizing tissues and inhibiting spores/hyphae in vitro. • W. anomalus enhances tomato disease resistance and suppresses black spot disease. • The survival rate reached 85.9 % with the optimal lyoprotectant formulation. • The survival rate of lyophilized W. anomalus retained 67.0 % after 90-day storage at -20 °C.