| Kiwifruit(Actinidia chinensis planch)have plenty of nutritious and minerals.The kiwifruit is difficult to store,because it is easily affected by disease.It limit the development of the kiwifruit industry.In order to study the post-harvest corruption mechanisms and biological preservation of kiwifruit fruit,and to explore the species of spoilage bacteria and their ability to cause spoilage during storage of kiwifruit,a combination of traditional isolation and culture methods with highthroughput sequencing was used to analyze the composition and change characteristics of spoilage bacteria during storage of kiwifruit,and to determine the dominant spoilage bacteria.,At the same time,analysis the putrefaction ability of the isolated spoilage bacteria and analysis of the antibacterial activity of Bacillus.The main results were as follows:1.Using high-throughput sequencing technology to study the changes of kiwifruit spoilage fungus community during different storage stages,showed that fruit p H dropped from 3.70 to3.31,TSS increased by 5.02% and the weight loss rate reached 58.60%.High-throughput sequencing of 35 samples in 7 stages,a total of 2801967 high-quality fungal sequences were obtained.As storage time to grow,fruit was gradually decaying,community richness also was reducing.Ascomycota is the dominant fungal phylum,accounting for 89.6% of the total sequence.The dominant fungal genus were Neofusicoccum,Botryosphaeria and Diaporthe.2.Through the correlation analysis between physical and chemical indicators and fungal community composition,with the increase of storage time,the richness of the flora in the fruit gradually decreased,and the diversity,uniformity and coverage were relatively stable.The weight loss rate was significantly negatively correlated with the Chao1,Observed species,Simpson,Shannon and Pielou’s evenness index of spoilage fungi,TSS content was significantly negatively correlated with Chao1,Observed species and Simpson index,p H was significantly positively correlated with Chao1,Observed species,Simpson,Shannon and Pielou’s evenness index.The weight loss rate and TSS content were significantly positively correlated with the dominant fungus Neofusicoccum,The main indicators of fruit have no correlation with other fungi.3.A total of 15 fungi and 16 bacteria were obtained by isolating spoilage microorganisms.The results of the back-linking experiment showed that the 10 fungi and 4bacteria had a rot-causing effect.It can be known by morphological and molecular biological identification,Z-1 is Fusarium verticillioides,Z-2 is Diaporthe cf.nobilis,Z-3 is Diaporthe sp.,Z-4 、 Z-5and Z-9 are Botryosphaeria dothidea,Z-6 is Diaporthe vaccinii,Z-7 is Colletotrichum fructicola,Z-11 is Diaporthe melastomatis,X-13 is Streptomyces champavatii,X-1 is Bacillus subtilis,X-4 is Acinetobacter johnsonii,X-5 is Bacillus velezensis,X-10 is Priestia aryabhattai.4.Using three kinds of bacillus YB-1、YB-2、YB-3 and chitosan to carry out antibacterial activity experiments on the isolated spoilage bacteria.The results showed that the three kinds of bacillus strains had antibacterial effect on 14 strains of decay-causing bacteria.The mixed bacterial solution has better antibacterial effect,The fresh-keeping effect of spraying kiwifruit with YB-1-2 mixed bacterial solution at room temperature was the best,compared with the control group,the relative control effect on kiwifruit is 48%.In this study,the combination of isolation culture and high-throughput sequencing method was used to analyze and identify the dominant spoilage flora of kiwifruit during storage.At the same time,bacillus and chitosan were used to analyze the antibacterial activity against spoilage fungi.Providing a theoretical basis for the study of kiwifruit decay mechanism and biological preservation. |
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