Cryptococcus laurentii combined with Bacillus tequilensis reduce blue mould by enhancing disease resistance and modulating the microbial community structure in Bingtang orange peel

Microbial antagonists are promising agents for controlling post-harvest diseases. Here, we examined the effectiveness and disease resistance mechanisms of the combined application of Cryptococcus laurentii and Bacillus tequilensis to combat postharvest blue mould in Bingtang oranges. The combined treatment effectively controlled the mycelial growth and conidial germination of Penicillium italicum in vitro, as well as significantly reducing the incidence of blue mould. This combined approach also enhanced extracellular chitinase and β-1,3-glucanase activities, resulting in increased cell membrane damage and leakage of cellular compounds. Additionally, the combined treatment altered the bacterial and fungal community structures on the fruit surface, thereby promoting the ecological balance of postharvest storage of the fruit. Furthermore, the application of the C. laurentii and B. tequilensis combination increased the activity of disease resistance-related enzymes (peroxidase (POD), polyphenol oxidase (PPO), phenylalanine ammonia-lyase (PAL), chitinase (CHI), and β-1,3-glucanase (GLU)) and led to the accumulation of total phenolics in Bingtang oranges. Thus, the combined application of C. laurentii and B. tequilensis effectively controlled postharvest green mould in Bingtang oranges.