| In the study, endophytic bacteria was isolated and screened from medicinal plants——Catalpa ovata G Don by tissue isolation method and obtained a strain NO.ZSYB-1 which has antibacterial activity against 6 plant pathogenic fungi. This study focused on the taxonomical status, the control of pest, antibacterial materials, growth-promoting, and field efficacy of the strain NO.ZSYB-1. The results were as follows:(1) Isolated and purified 27 strains of endophytic bacteria from the different tissue of Catalpa ovata G Don and antagonistic strains on Alternaria solani was selected by plate confrontation method. The result showed that 17 strains had antibacterial activity, accounted for 63% of the total and the inhibition rate ranged from 2.3% to 94.3%. Two strains NO.ZSYB-1 and NO.ZSG-3 had stronger antibacterial activity. Tested the antibacterial activity of the two strains and their metabolites on 6 kinds of pathogenic fungi. The study indicated that the strain of ZSYB-1 presented much better antibacterial activity for 3 pathogenic fungi(Botrytis cinerea, Alternaria alternate and Alternaria solani) and the inhibitory rate more than 80%. So the strain of ZSYB-1 was an excellent biocontrol strains. According to morphological, biological and biochemical characteristics, the strain ZSYB-1 belonged to Bacillus spp. Then the strain ZSYB-1 was identified as Bacillus amyloliquefaciens by analysis of the 16S rDNA sequence.(2) Antibacterial substances result show that the antibacterial substances not only has stronger heat stability, pH stability and UV stability, but also has stronger surface activity. The inhibitory rate was more than 80%, when the temperature was 25??121? or the pH was 3-12 or the time of UV was 2h-12h. Antibacterial substance was identified as lipopeptide. The diameter of antibacterial circle of lipopeptide on Alternaria solani was 24 mm. Antibacterial substance was purified into five fractions by the chromatography system, which fraction 3 and fraction 5 showed stronger antibacterial effect, the diameter of antibacterial circle was 28.6mm,14.5mm, respectively. But, peak 1,2,4 not. The result of TLC detection showed that the antibacterial substance of peak 3 was cyclic lipopeptide.(3) The results of culture conditions showed that the best basic culture medium was BPY, the best carbon source was glucose, the best nitrogen source was peptone+beef extract+ yeast powder, he optimal fermentation parameters were 30?, pH 7.0, inoculation 3 mL, volume 200 mL and culturing for 72 h.(4) Promoting effect analysis showed that the strain ZSYB-1 and the 10 times dilution of strain ZSYB-1 fermentation could significantly promote germination rate of tomato seeds, the growth of tomato seedlings, and improve the enzyme activity of SOD, POD and CAT. In addition, the strain ZSYB-1 has much better promotion effect than the fermentation liquid.(5) The control effect showed that the strain ZSYB-1 and fermentation liquid had certain control effect in vitro conditions. With the increase of fermentation dilution, the control effect showed a downward trend. The control effect greatly reduced, when dilution was 20 times, only 18.42. In field conditions, different inoculation time resulted in significantly different control effect. The control effect was 63.20%, when the fermentation liquid and Fulvia fulva (Cooke)Cif were inoculated together. So fermentation liquid had a certain therapeutic effect. However, the control effect (66.56%)was much better than incubated at the same time (41.89), if the strain ZSYB-lwas incubated before Fulvia fulva (Cooke) Cif. So the strain ZSYB-1 had better prevention effect. |
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