Mechanisms Of Trehalose On Viability And Biocontrol Efficacy Of Antagonistic Yeasts

In recent years, biocontrol on fruit postharvest diseases using antagonistic yeasts becomes a hot topic. However, compared with synthetic fungicides, the efficacy of biocontrol formulation is not enough stable in the practical application. Because antagonisms are alive, their viability and biocontrol efficacy are easy to be effected by environmental factors, such as stresses during the process of formulating, distributing and applying, which limits the industrial production and commercial application of antagonistic yeasts. In order to improve their biocontrol ability, combining biocontrol yeasts with some chemical compounds has obtained good control effect. Additionally, enhancing tolerance of biocontrol agents to stress conditions is another useful approach. In the study, we researched the relationship between endogenous trehalose in antagonistic yeasts and their viability, as well as biocontrol efficacy. The endogenous trehalose content was improved by a physiological method. Then the effects of endogenous trehalose content on viability and biocontrol efficacy of antagonistic yeasts subjected to various stresses and involved mechanisms were investigated. The results were presented as following:1. The trehalose content in Cryptococcus laurentii was increased by culturing the yeast in trehalose-containing medium. Improving of endogenous trehalose level not only increased the viability of the yeast in vitro, but also enhanced its population and biocontrol efficacy against Penicillium expansum on apple fruit both at 1 oC and in controlled atmosphere condition (1 oC, 5 % O2, 5 % CO2). After freeze drying, survival of the yeast with high trehalose level was markedly increased, and one of the reasons might be that trehalose gave an effective protection to plasma membrane.2. Beside C. laurentii, the accumulation of endogenous trehalose in antagonistic...