Study On Endophytic Fungi And Poilage Bacteria Of Actinidia Arguta

The Actinidia arguta(Sieb.et Zucc.)Planch.ex Miq is one of the wild varieties in the Northeast of China.It has high nutritional value which is rich in a variety of trace elements and mineralsand Vc content is extremely high.Because the fruit skin is thin and juicy,it is easy to soften and rot at room temperature.There is no comprehensive report on the changes of spoilage bacteria in Actinidia arguta.In order to explore the main physical and chemical factors that cause changes in endophytic fungi,and to study the spoilage mechanism of Actinidia arguta,traditional separation and cultivation methods and high-throughput sequencing were used to analyze the characteristics of spoilage bacteria during storage of Actinidia arguta.The main results were as follows:1.Sensory indexes and physiological and biochemical indexes of Actinidia arguta(Sieb.et Zucc.)Planch.ex Miq at different picking times were measuredand the results showed that it reached the morphological maturity period on September 2.High-throughput sequencing results showed that the dominant fruit fungi of the fruit are Ascomycota and Basidiomycetesand the predominant genus is the genus Diaporthe,according to the analysis of the ? diversity index,it was found that the abundance and diversity of the fungal community within the fruit become higher as the picking period is extended;Between fruit physical and chemical indexes and?diversity index analysis of correlation: The water content in the fruit was negatively correlated with Chao1,ACE index;the reducing sugar content was positively correlated with Chao1,ACE,Shannon,Simpson,and had a certain significance.Correlation analysis between fruit indicators and dominant fungi showed that: absolutely dominant fungal genus Sphaerulina was negatively correlated with water content and hardness positively correlated with TSS,reducing sugar content and chlorophyll content,with certain significance;Cladosposporium was inversely related to the content of titratable acid and was extremely significant.2.The traditional culture method was used to isolate the spoilage microorganisms in the rotten fruitwhich includ a total of 6 fungi and 6 bacterias.The fungus was identified by molecular biology SP-1 was Alternaria brassicae,SP-2 was Fusarium concentricum,SP-4 is Alternaria alternata,SP-6 was Alternaria tenuissima,SR-1 was Fusarium acuminatum,SR-2 is Fusarium verticillioide.Bacterial morphological identifications were all Gram-positive bacteria,SP-1 was Bacillus aryabhattai;SP-2 was Bacillus subtilis;SP-3 was Alcaligenes faecalis;SP-4 was Curtobacterium oceanosedimentum;SR-1 was Bacillus velezensis;SR-2 was Bacillus amyloliquefaciens.The results of the back-linking experiment showed that the six fungis had a rot-causing effect,and only SP-4 bacteria had an effect on fruit quality.3.High-throughput sequencing were used to study on the changes in the peel and pulp spoilage fungal community at different storage times showed that 878967 high-quality fungal sequences were obtained from 20 samples.The abundance of spoilage fungi contained in the peel was higher than the pulp,and the content of spoilage fungi at the bottom of the fruit was higher than the tip.The dominant spoilage fungi in the phylum level was Ascomycota,accounting for 91.3% of the total sequence.The dominant spoilage fungi at the genus level include Diaporthe and Phamopsis,accounting for 39.9% and 24.4% of the total,as the storage time prolonged,the content of the Diaporthe decreased;Colletotrichun and Malassezia were extremely abundant at the bottom of the peel.