Screening And Identification Of Antagonistic Actinomycetes Of Potato Fungal Diseases

Potato is the fourth most important crop in the world after wheat,rice and corn.Gansu province is one of the main potato producing areas,potato is also the major food crops and cash crops of province,the most areas of the province is also suitable for planting potatoes.In recent years,potato cultivation area continues to expand,leading to its fungal diseases generally occur,seriously affecting the potato yield and quality.At present,the main use chemical pesticides and stubble to prevent and control their disease,but the pollution of the environment is serious,leading to pathogen resistance and not too much for the fall of the land makes the potato disease prevention and control did not get a better solution.Biological control is an important way to solve this problem because it can avoid the above shortcomings.Antagonistic microorganisms are an important source of bio-pesticides,and actinomycetes are a kind of microbiological group with great application value.In the agricultural production and new drug screening has a huge application prospects.The main purpose of this study was based on the three potato pathogens as target pathogens,isolating and screening the actinomycetes with antibacterial effect from Saline-alkali Soils in Hexi Corridor,identificate it and optimize it's culture conditions that has strong antibacterial activity.It will provide new microbial resources for the biological control of potato fungal diseases.The specific results are as follows:1?To get the strong antibacterial activity strain to potato disease,use tablet confrontation screening actinomycetes with antibacterial effect from Saline-alkali Soils in Hexi Corridor.The finally result of screeing from 165 actinomycetes which isolated from hexi corridor was that 25 of them have inhibition activity and which calculated as 15.15%,8 strain among that have inhibition activity to 3 strains of potato pathogen and which calculated as 4.8%.2?Growth rate method was used to rescreen the strains which have higher antagonism diameter,The result showed:Strains XA06225,XD05210 and XA05216 had a good inhibitory effect on mycelial growth of three pathogenic fungi.3?Combined with the screening and re-screening results,screening out a strain of excellent actinomycetes,numbered XA06225.The result show that the strain XA06225 have a good inhibition result to Fusarium solani,Rhizoctonia solani and Alternaria solani,and the inhibition maximum diameter of them were 5.03 cm,3.21 cm and 2.11 cm respectively.The inhibition effect of XA06225 to Fusarium solani,Rhizoctonia solani and Alternaria solani,and the inhibition effect of them were 31.36%,25.41%and 19.32%respectively.4?Combing the morphology,culture characteristics,physiological and biochemical characteristics and 16s rRNA gene sequence to identify the theories of system development of the strain XA06225,preliminaryly identificate the strains XA06225 as Streptomyces globisporus of Streptomyces.5?The optimization conditions of single factor experiment results to strain XA06225shows that the optimum carbon source was glucose,the optimum nitrogen source was KNO₃.The optimal culture medium conditions obtained by orthogonal experiment was milet dipping sauce 1%,glucose 2%,KNO₃ 0.6%,NaCl 1%,CaCO₃ 0.2%,pH=7,the inhibition rate of XA06225 achieved to 79.11%to Fusarium solani,under the condition.In vivo experiments showed that the strain XA06225 had significant effect on the control of potato dry rot,followed by 65.45%.6?Extraction of XA06225 strain's filtered liquid.Used three different extraction agent petroleum ether,ethyl acetate and butyl alcohol.Geting the result that the inhibition rate of it was 51.3%,So best extraction solvent is butyl acetate.