Screening Of Antagonistic Bacteria And Preliminary Analysis Of Antagonistic Substances Of Citrus Sand Bark Bacteria

Diaphorina citri has become one of the main pathogens of Citrus disease,which is mainly affect appearance leads to a decrease in the price of Citrus every year,causing major economic losses to agricultural production.The prevention of Citrus disease still rubber chemical prevention,although can play a role but it will bring about a series of problems such as the pharmacy toxic,easy to cause heavy metal pollution to the environment,pose a threat to human and animal health.With the high toxic pesticides in the disabled in our country,and people's awareness of environmental protection continue to strengthen the development of green environmental protection,safety of biocontrol agents to control citrus disease rubber and other plant diseases and insect pests It has become the key goal and direction of people's research.In this study,the bacteria in the soil were isolated and screened,and a strain Y2 was obtained,which had a high inhibitory effect on citrus bark disease.It was identified by morphological,physiological,biochemical and molecular biological techniques,and its inhibitory effect was further improved by optimizing its culture medium and fermentation conditions,and the antimicrobial activity of antagonistic bacteria Y2 was preliminarily studied and analyzed.The main findings and findings are as follows:1.In this experiment,soil dilution method was used to isolate bacteria from different soil samples with fertile soil quality and abundant microbes in Changsha City and Xiangxi Autonomous Prefecture.The bacteria isolated from soil were screened by direct plate confrontation method,and 4 strains with high inhibitory activity were obtained.By the method of 5 times and 10 times dilution of fermentation broth,it was found that the fermentation broth of Y2 had the best inhibitory effect on Diaphorina citri.After the supernatant of fermentation broth was treated with 5 times and 10 times diluent,the citrus peel was treated.and the inhibiting effect of the germs is 60 percent and 50 percent respectively.2.The taxonomic status of Y2 strains was preliminarily determined by morphological observation,physiological and biochemical observation,phylogenetic analysis of 16 s rDNA sequence.It was preliminarily considered that the active strain Y2 was Bacillus pumilus.3,through optimizing the fermentation conditions of Antagonistic Bacterial Strain Y2 and screening medium through the optimization to determine the nitrogen and carbon source formula: 30g/L soluble starch,peptone 4g/L.and fermentation conditions of single factor screening,to determine the optimal fermentation conditions of strain Y2 inoculation volume of 8%,at the age of 36 hours,200r/min speed,pH value of fermentation time of 7 and 5 days.4.Through the field control of the metabolites of strain Y2,it was found that the fermentation broth of strain Y2 coulat strain Y2 can effectively inhibit pathogenic bacteria,and has certain practical application value.