Antibacterial Characteristics Of Excellent Biocontrol Bacteria And Development Of Microorganism Inoculant

Microbial pesticide is a new kind of“environment-friendly”biological pesticide,which contains microorganisms and metabolites of microorganisms that can not only prevent and control disease,insect and grass damage,but also promote plant growth.With the publication of the National 13th Five-Year Science and Technology Development Plan and the the Rural Revitalization Central Document No.1“Green Development”lead in2018,ecological agriculture has been included in the new emerging industries,and pest prevention and control is the key research direction in the agricultural field.Therefore,the development of microbial pesticides has become the research and development hotspot of new environmental biological pesticides.In order to improve the inhibition of microbial pesticides on pathogenic fungi and the effect of microbial pesticides on the control of plant diseases.We studied identification of pathogenic fungi of seven species,there were choosed eight strains by us from the laboratory of grassland biodiversity,and four strains with better antagonistic effect were screened and identified.With different concentrations of humidifiers(Tween-20,Tween-80 and OP emulsifiers),UV protectants(Sodium alginate,Sorbitol and Xanthan gum)and preservatives(Methylparaben,Ethyl acetate,Kesson and Sodium citrate),three types additives were put in mixed biocontrol bacteria,to detect MBB growth changes and screen the optimal type and concentration of additives.We developed and tested the quality of microbial pesticides.The effects of microbial pesticides on leaf and root diseases of oat seedlings and their growth were studied by us.In order to solve the problems of short storage time,easy pollution and low utilization rate in microbial pesticides,there were a foundation forage diseases of the prevention and control and the quality of improvement.The results were as follows:1.Seven crop pathogenic fungi were identified.The wheat root rot fungus PB1 was Bipolaris sorokiniana,the tomato early blight PB2 was Alternaria alternatea,the cucumber wilt PB3 was Fusarium oxysporum,the highland barley stem rot pathogen PB4was F.chlamydosporum,the maize leaf spot pathogen PB5 was Curvularia lunata,the highland barley root rot fungus PB6 was F.avenaceum and oat root rot PB7 was F.equiseti.2.Four excellent biocontrol bacteria were screened and identification by us from 8strains of bacteria.The results showed that GAU-88 had an impact on PB1in the inhibition rate,it was up to 83.29%,followed by GAU-86(67.47%)in the inhibition rate.The inhibition rates of GAU-24 and GAU-85 on PB2 were 70.73%and 60.98%respectively.The inhibition rate of GAU-39 was up to 83.29%on PB3,followed by GAU-88(80.99%).The inhibition rates of GAU-39,GAU-24 and GAU-85 had impact on PB4,which were73.41%,71.32%and 68.92%,respectively.The highest inhibition rate of GAU-68 was77.92%and 75.30%on PB5 and PB7 respectively.The highest inhibition rate of GAU-88 was 74.56%on PB6.Biocontrol bacteria of four strains had good antagonistic effect,and the identification results were Bacillus mycoides(GAU-68),Brevundimonas faecalis(GAU-88),B.velezensis(GAU-24)and B.xiamenensis(GAU-39),respectively.3.Different concentrations of humidifiers,UV protectants and preservatives had different effects on the growth of mixed biocontrol bacteria.The results showed that Tween-80 was more suitable as wetting agent for mixed biocontrol bacteria than OP emulsifier and Tween-20,and its suitable mass fraction was 1.00%.Compared with sodium alginate and xanthan gum,sorbitol was more suitable as UV protection of mixed biocontrol bacteria,and its suitable mass fraction was 0.50%.Compared with Ethyl ethyl acetate,Kesson and Sodium citrate,Methylparaben was more suitable as preservative of mixed biocontrol bacteria,and its appropriate mass fraction was 0.50%.The best combination ratio of the three additives was carried out by the central combination test and response surface analysis(This invention was declaring patent).4.The developed biocontrol agent met the requirement of agricultural microbial standards(GB 20287-2006).The effective live bacteria count,impurity count,impurity rate and pH were 3.10×10~9 cfu/mL,55.00×10~4 cfu/mL,0.0092?and 7.46,respectively.5.The developed microbial biocontrol agent had a good effect on the growth and disease control of oat.The inhibition rate of the microbial pesticide on all 7 pathogenic fungi can reach more than 68.00%,among which the inhibition rate on fusarium can reach70.07%.Compared with the control group,the control effects of microbial pesticides on oat leaf and root diseases were 46.21%and 45.57%,respectively.The plant height of oat seedlings increased by 0.43~10.96%,and the biomass increased by 1.44~3.66%.