| An antagonistic strain Bacillus subtitlis produce large amount of antifungal substance with strong inhibiting activity against plant fungi.We obtained aberrance of the Strains that was implated by the technology of low energy ion.In this paper,research on control effect of the aberrance against postharvest anthracnose caused by Colletotrichum gloeosporioides.At the same time,growth and fermentation conditions,optimization of fermentative culture media,antagonistic mechanism were studied on.The experimental results were summarized as follows:1.Mutagenicity and screening high effiency antagonistic strain of Bacillus stubilisAn antagonistic strain Bacillus subtitles produce large amount of antifungal substance with strong inhibiting activity against plant fungi.We obtained aberrance of the Strains that was injected by the technology of low energy ion.In plate test,6 strains of aberrance which can effectively control postharvest Anthracnose of apple fruits were screened out.And then the strains were studied to screened out the best strains that can control anthracenose from in vivo test.under differenet temperature with different inoculation type,the type two is better than type one.in different temperature showed out:Strain BS80-6 has better control effect under room temperature,The control effect is 33.28%;strains BS100-1,BS100-6,BS80-6,BS120-8 are better under low temperature,The control effect are 98.36%,95.36%,95.52%,93.52%respectively after thirth day;strains BS80-1,BS100-1,BS120-8 are better under changed temperature,The control effect are 84.59%,75.15%,72.40% respectively after thirth day.At the same time,induced strains have control effect on acervulus development of Colletotrichum gloeosporioides,the results as follow:BS80-6,BS100-6(at room temperature);BS100-1,BS100-6,BS120-8,BS80-6(at low temperature).Strains BS80-6,BS120-8,BS80-1 have control effect on latent infection. The fermitive liquid has the best inhibition and control effect in the three treated liquid.2.Study on the aberrance genetic stability of Bacillus stubilisIn order to use the mutated strain in pratice,it must have genetic stability in control effect,In this test,the induced strain were inoculated seven time from the first strain,choicing the third,fifth and seventh time to test with in vivo respectively,,the result showed that it has genetic stability in control effect against Colletotrichum gloeosporioides. 3.Study on growth and fermentative conditions of Bacillus subtilisThe single factor and the general quadratic rotatory regression tests were used to optimize the fermentative culture media of strains screened from aberrance of the Strains that was injected by the technology of low energy ion.It is shown from the test results that the optimal culture medium ingredients are glucose,peotine,KCl,riboflavin(VB6).The optimization of medium on the two isolates from Mongolian snakegourd anthracnose was studied by using the general quadratic rotatory regression of three factors and five levels in this experiment.The effects of combined pH value,glucose content,petpone content,KCl,riboflavin(VB6)on the number of live bacteria of fermentation.The mathematic model of reaction on the medium was built up,which was of high predication and verified by the experimental data to be reliable.The reaction regularity and relation between the each factor in the best combination of the number of live bacteria in the number of live bacteria of fermentation and the mutual effect of different factors were discussed by use of the mathematic model,and compared the factors which affected the growth of two strains.The results showed the requirements were different between the growth of BS80-6and that of BS-CK.The important order of the effect of each factor on the the number of live bacteria of BS80-6 fermentation was riboflavin(VB6)＞peotine content＞pH value＞KCl＞glucose content.The important order of the effect of each factor on the number of BS-CKwas pH value＞KCl＞glucose content＞petpone content＞glucose content.The important order of the effect of the interaction between two factors on the BS80-6 growth value was the interaction between pH and petpon＞glucose and riboflavin＞pH and glucose＞glucose and KCl＞KCl and riboflavin＞glucose and petpone＞pH and KCl＞pH and riboflavin＞petpone and KCl＞petpone and riboflavin,the interaction between pH and petpone,KCl and riboflavin,glucose and petpone were significant different.The important order of the effect of the interaction between two factors on the BS-CK growth value was the interaction between glucose and petpon＞glucose and riboflavin＞pH and KCl＞glucose and KCl＞KCl and riboflavin＞glucose and petpone＞pH and riboflavin＞pH and KCI＞petpone and KCl.The interaction between pH and petpone,pH and glucose,glucose and riboflavin were significant different.And then the fermentative contions were studied,the results show that the optimal fermentation pH value is7.0-8.0,and the optimal fermentation temperature is 25-28℃. The optimal fermentation Oxygen is fill with 50mL liquid media in a flask.The optimal fermentation periods is determined to be 72 to 80 hours based on the growth curve of the stains in the fermentation liquid.4.Study on the antagonistic mechanism of Bacillus stubilis to Colletotrichum gloeosporioidesThe aberrance strains of Bacillus subtitlis that was implated by the technology of low energy ion has high control effect on Colletotrichum gloeosporioides.In the dual test on PDA plates,the antagonistic strains could significantly inhibit the pathogen growth and the fermination liquid could significantly inhibit conidial germination of the pathogen.The antimechanisms of the antagonistic strains showed that it could break down hyphae,turn hyphal cells into swollen sacs,inhibit conidial germination.At the same time,By means of mensuration the changes of peroxidase(POD),polyphenoloxidase(PPO)and phenylalanine ammonia-lyase(PAL)of apple fruits that were inoculated with Colletotrichum gloeosp-orioides and antagonists simultaneously,the result also show that antagonist can induce resistance to Colletotrichum gloeosp orioides. |
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