Effect of Heat Shock Treatment on Stress Tolerance and Biocontrol Efficacy of Biocontrol Yeasts
2011
Liu, J. | Wisniewski, M.
Several different species of yeasts have been used as biocontrol agents against postharvest diseases of fruits and vegetables. Our current research is directed to develop a better understanding of yeast biology in relation to biocontrol activity and to develop strategies to improve the efficacy of their biocontrol activities. The effect of a mild heat shock (HS) pretreatment (30 min at 40°C for Metschnikowia fructicola; or 20 min at 40°C for Candida guilliermondii) on the tolerance of to subsequent high temperature (45°C) and oxidative stress (0.4 mol L-1 H2O2) was evaluated. The viabilities of the two yeasts subjected to both stresses were enhanced by the pretreatment. Additionally, the HS yeasts showed better biocontrol efficacy against Penicillium expansum and higher population on apple fruits stored at 25°C compared to the performance of untreated yeast cells. The trehalose content in M. fructicola or C. guilliermondii also increased. Results indicate that induction of trehalose content by HS pretreatment may contribute to improvement in stress tolerance, population dynamics and biocontrol efficacy of the two biocontrol yeasts.
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