Identification Of Pathogenic Bacteria Separated From Kiwifruit And Antimicrobial Effect Of Chitosan Schiff-bases Research

Objective: Separated and identified the pathogens from kiwifruit in different growth stages which cause rot of kiwifruit. And exploration the antifungal activity of four Chitosan Schiff-bases(CTS-Sal, CTS-2Hy, CTS-Val, CTS-O-val) on Pathogenic of kiwifruit. The preservation effect of Vanillin Schiff Base on kiwifruit was studied. Methods: The pathogen separated from kiwifruit was identified by morphology and molecular biology method. The MIC and EC50 of four Chitosan Schiff-bases were tested by trace dilution method and mycelial growth rate. Fresh kiwi fruit randomly was divided into 3 groups,One group was saved by soaked chitosan schiff base solution. Another was saved by freshness protection package. The preservation effect of each group was compared. SPSS17.0 was employed as statistical software for data collation, entry and analysis. Results: 1. 3 strains were isolated from kiwi fruit buds: Alternaria alterna, Penicillium steckii and Aspergillus fumigatus. 3 strains were isolated from fresh kiwi fruit: Cladosporium, Alternaria alternate and Colletotrichum karstii. 5 strains were isolated from rotten kiwi fruit: Alternaria sp, Cladosporium sp, Mollisia cinerea, Starmerella bacillaris and Penicillium steckii. 4 strains were isolated from cold storage rotten kiwi fruit: Cryptococcus flavescens, Penicillium brevicompactum, Aureobasidium sp and Rhizopus microspores. 4 strains were isolated from Kiwi fruit juice: Cladosporium sp, Penicillium steckii, Aspergillus versicolor and Bacillus firmus. 2. Antibacterial test indicated that four Chitosan and Chitosan Schiff-bases have inhibition effect on the pathogens separated from Kiwi fruit. The inhibition effect of chitosan schiff bases was stronger than that of chitosan.(CTS-O-Val) to be good inhibitory effect on yeast is better, MIC value was 250μg/m L.(CTS-Sal, CTS-2Hy) to be good inhibitory effect on Alternaria, MIC value was 125μg/m L 3. The preservation experiment results suggested that the storage time of kiwifruit was extended significantly by bagged with freshness protection package and infiltration of chitosan schiff base solution. The combination of freshness protection package and chitosan schiff base solution was the optimum condition.. Conclusion: 1. The primary pathogens led to the rot of kiwi fruit were Alternaria alterna, Penicillium steckii and Cladosporium under aerobic environment at room temperature. Under the anaerobic environment, however, the main pathogen causing the rot of kiwi fruit was yeast. And the pathogens under the cold storage condition were Cryptococcus flavescens, Penicillium brevicompactum, Aureobasidium sp and Rhizopus microspores. 2. Chitosan and four chitosan Schiff-bases showed certain inhibition effect on the pathogens separated from Kiwi fruit which show antibacterial activities. Among them, Chitosan Vanillin Schiff Base(CTS-Val) was the potential candidate as the fruit fresh-keeping agent with excellent antibacterial activity and special cream smells. 3. Infiltration of chitosan schiff base solution and isolation of oxygen by freshness protection package can extend the storage time of kiwi fruit.