The screening and the efficacy of a marine antagonistic yeasts on control postharvest disease

LIU Jia,ZHANG Jian-lei,WANG Xiang-hong,CHEN Mei-qun,MENG Xiang-hong(College of Marine Life Science,Ocean University of China,Qingdao,266003)

marine yeast;screening;Aureobasidium pullulans;postharvest biocontrol;Botrytis cinerea

The living environment of marine yeast is low temperature and high concentrations of NaCl,so it may have some excellent properties such as good tolerance to low temperature and high osmotic stress.Once the marine yeast is applied in the postharvest biocontrol,it may have more advantages than other terricolous microorganisms.After screening of 61 yeast strains isolated from different marine environmental conditions,4 strains were found to be effective antagonists against Botrytis cinerea.Among them,the strain DG-1 showed the highest antagonistic activity.DG-1 was identified as Aureobasidium pullulans preliminary by the morphological,physiological,biochemical and molecular methods.After assaying the mycelial growth against the pathogenic fungi in vivo,it was found that the inhibitory effect was stronger with the yeast concentration.However,it could not completely inhibit the spore germination of Botrytis cinerea.The cell suspension had significant effect while the heat-treated medium had no inhibitory efficacy.Therefore,it was initially demonstrated that the biocontrol mechanism of A.pullulans belonged to the type of nutrition competition.In additional,the growth conditions of the DG-1 were optimized in this study.