Identification Of Endophytic Bacteria MY1 From Datura Stramonium And The Study On Antifungal Activity Of Pyricularia Grisea

This study of endophytic bacteria have inhibitory effects in the valley of Pyricularia grisea were screened,one strain with antibacterial activity of various pathogenic fungi endophytic bacteria MY1 strain,and the taxonomic status,fermentation condition,the fermentation filtrate of physicochemical properties,antibacterial mechanism,growth promoting and biocontrol effect and antibacterial substances etc.The study provides a theoretical basis for the development and application of microbial pesticides.Its specific research results are as follows:1.Stored in the laboratory screening of endophytic bacteria with high antibacterial activity of Pyricularia grisea by plate confrontation method and growth rate method,bacteriostatic effect on strain MY1 the best antibacterial spectrum determination,the results showed that the strains in vivo and its fennentation liquid on B.cinerea,M.fructicola and V.Mali etc.All pathogenic fungi have better antibacterial activity,especially B.cinerea and M.fructicola can significantly inhibit the growth of fructicola,the fennentation broth on the inhibition rate was up to 90%.The strain MY1 was identified as Bacillus methylotrophicus by morphological observation,physiological and biochemical identification and 16S rDNA sequence analysis.2.The growth curve of strain MY1 was determined by turbidimetric method.The results showed that the 0?12h of MY1 strain was retarded,12?32h was logarithmic,32?56h was stable,56?72h was decline.Method by single factor test and orthogonal test to optimize the fermentation of MY l strain,medium composition and fermentation results showed that the best fermentation MY1 basic medium was BPY,the best carbon source was the best nitrogen source for lactose,beef extract and yeast powder,the optimum culture conditions:temperature 28?,pH 9.0,medium volume 100mL/500mL,inoculum 2%,speed 160r·min-1.fermentation time is 96h.3.The physical properties of the metabolites of the strain showed that the fermentation ability of MY1 fermentation broth was good,and the droplet on the parafilm film collapsed obviously,indicating that the metabolites contained lipopeptide substance and had surface activity4.By microscopic observation and conductivity of MY1 strain of antibacterial mechanism,the results showed that the strain MY1 fennentation liquid treatment,R grisea mycelium appeared abnonnal growth,fracture,including material overflow;cell membrane penneability of P.grisea increases with MYI fermentation liquid treatment time,damage to cells increased5.The deternination results of stability of fermentation broth showed that the thermal stability of fermentation broth of strain MYI had better inhibitory rate of 100? was maintained above 90%;very stable in acid environment,the inhibitory rate was maintained above 90%;antibacterial substance is not sensitive to ultraviolet light and natural light;room temperature under the condition of the save 60d inhibition the.grisea rate can still reach the original antibacterial activity of 88.49%under 4?;save 60d,inhibition of P.grisea rate can still reach the original antibacterial activity 86.32%6.The detection results of antibacterial substances produced by MYI strain showed that MY1 strain could produce extracellular protease and cellulase(?-1,4-glucan ASE),and could not produce chitinase,?-1,3-dextran,indole-3-acetic acid(IAA),and had no ability to dissolve phosphorus.7.By seed soaking and root irrigation method determination of MY1 fermentation filtrate on the millet seed germination and seedling growth.The results showed that the germination index of original culture filtrate on Millet seed is the highest;with 20X dilution on seedling growth promoting effect of the best,the control group of millet seedling height,root length,fresh weight and dry weight compared with sterile water treatment were increased by 30.15%,36.84%,20.25%,42.11%,while high concentration will appear different degrees of inhibition by MY1 fermentation filtrate;after different concentration effects on Millet defense enzme activity indicated that strain MY1 did have a certain role in plant defense enzyme activity of millet to improve.