Effect Of Heat Shock On Stress Tolerance And Biocontrol Efficacy Of The Antagostic Yeast Rhodotorula Mucilaginosa

Biological control of postharvest diseases, based on antagonistic yeasts, is an eco-friendly management method. A few yeast-based biocontrol products are either commercially available or in the stages of advanced development. Ecological fitness, stress tolerance and biocontrol efficacy of yeasts are essential for biocontrol agents. A heat shock (HS,40℃ for 30 min) pretreatment of the antagostic yeast, Rhodotorula mucilaginosa, increased its tolerance to subsequent stresses, including high temperature (48℃), oxidative stress (70 mM H2O2), salt stress (3 M NaCl), as well as low pH (pH 4). Stimulation of the antioxidant system by HS resulted in a lower intracellular reactive oxygen species (ROS), and less oxidative damage to proteins and lipids in yeast cells when subjected to these abiotic stresses. In addition, HS-treated yeast exhibited increased biocontrol efficacy against Penicillium expansum on apple fruit. P. expansum was isolated from infected apple fruit, and cultured on PDA plates. It has been identified by amplification of ITS region using the general pair of primers of ITS1 (F) and ITS4 (R). These results suggest that stress adaptation (e.g., HS) represents a viable approach for enhancing the efficacy of yeast biocontrol agents against postharvest diseases of fruits and vegetables.