| The postharvest diseases of fruits and vegetables often cause great damage, the main measure to control it is using the chemicals now, but there are many concomitant problems in the fields of chemical residues, the pollution of environment , the resistance of chemical ,and so on. With the advance of people's consciousness of health and environmental protection, that biocontrol as a new way to control the postharvest diseases is accepted by people gradually, and being a hot research spot now. Biocontrol has advantages of security, long-kept effect and no pollution to natural environment, which was also applied at the period of plant growing and fruit preservation . Biocontrol will be the most useful method to control the postharvest diseases and it will replace the chemical control in the future.The previous studies show that bacteria, filamentous fungi and yeasts can be used as the biocontrol microorganism. Yeasts have the advantages of good biology control effect, low nutrition demand, rarely producing toxin and almost no damage to people's health, clear genetic background, efficiently genetic transform system, the genetic modification potential to enhance their biocontrol effect, abundant nutrition in cells, and many yeasts are wildly used to the food and fermentation industry which have a close relation to people's life. Therefore yeasts become the main strains to control the postharvest diseases of fruits and vegetables.The experiment material are the 620 strains of yeasts isolated from the west China provinces (Xinjiang,Gansu,Qinghai,Shanxi,Ningxia and Tibet ) which are conserved in molecular biology laboratory ,Shandong Institute of Light Industry. With the method of agar block and using Staphylococcus,Coliform and Penicillium expansun,rhizopus stolonifer which are the main diseases of postharvest fruits and vegetables. Through the first and second screening experiment, there are 11 strains that can inhibit the Penicillium,6 strains that can inhibit the Rhizopus stolonifer and 9 strains that can inhibit the staphylococcus,but there's no strain can inhibit the coliform.Among the largest diameter of the inhibition zone, the GS9B strain reaches 18.6mm resistant to Penicillium expansun, the 67A strain reaches 18.0mm to Rhizopus stolonifer and the GDC strain reaches 30.2mm to Staphylococcus aureus.The antibiogram experiment was done with the strains YQY Carbernet Sauvignon,GS9B,67A,Qch qingcheng,GDC,Qch3,GS9D.The result showed that the GDC strain has the widest antagonism range which can inhibit 7 types of diseases microorganisms,the Qch qingcheng and Qch3 can kill 4 kinds of diseases,the strain 67A can inhibit 3 kinds of diseases;The mixed use and the apple spraying experiments in vivo indicated that there is a positive correlationship between the concentration of the antagonism yeasts and biocontrol effect . The antagonism yeasts inoculated lag or at the same time with pathogen spores can maintain the biocontrol effect, but the antagonism yeasts inoculated ahead of pathogen spores has the best biology control effect. The antagonism strain of GDC and Qch qingcheng strains which has the best biocontrol effect to Penicillium sp. and 67A strain which has the best biocontrol effect to Rhizopus sp. were analysed,the result shows that GDC strain can secrete small proteins outside cells and GS9B,67A,Qch qingcheng can produce antagonism components in cells or the competition of nutrition and space with pathogen.The strains YQYcarbernet sauvignon,Qch qingcheng,GS9B,GS9D,67A,Qch3,Qch4 were identified based on 26S RNA D1/D2 domain characterization.The result shows that the 67A,Qch3,Qch4 strains belong to Metschnikowia pulcherrima,the YQY Carbernet Sauvignon belongs to Hamseniaspora uvarum,the GS9B and GS9D strains are new genus identified by LiuTianming and Xu Meixin. |
