Identification and Evaluation of Bacillus subtilis SF18-3 Against Bacterial Spot Disease of Pepper
In recent years,bacterial spot disease of pepper[Xanthomonas campestris pv.vesicatoria(Doidge)Dye]has occurred seriously in Liaoning province.In this study,a strain of biocontrol bacterium SF18-3,known for its high efficacy,was obtained from a mixture of animal manure using the dilution plate coating method.The target organism for this isolation was bacterial mottle blotch BWB3 in pepper plants.To further clarify the biocontrol effect of SF18-3,the optimal fermentation conditions were optimized by antibacterial zone method,and the 6 extracellular enzyme activities were determined by double antibody sandwich method.The antibacterial activities were determined in laboratory test and the control efficiency were evaluated in pod experiment.The taxonomic status of SF18-3 was determined by morphological characteristics observation,physiological and biochemical tests and 16S rDNA sequence analysis.The results showed that SF18-3 had the best bacterial inhibition effect after fermentation for 84 h at 30℃with NB as the basal medium at 140 r·min-1.The protease activity and xylanase activity in the fermentation broth were higher,which were 536.13 U·L-1 and 564.22 U·L-1,respectively.Under optimal fermentation conditions,the diameter of the transparent circle was 3.40 cm on the plate and a 70.17% control efficiency on potting.SF18-3 was rod-shaped,spore,Gram-positive bacterium,and 16Sr DNA sequence was clustered with Bacillus velezensis OK169608 and B.velezensis OK147645.According to colony morphology and physiological and biochemical characteristics,strain SF18-3 was identified as B.velezensis.
bacterial spot disease of pepperBacillus velezensisextracellular enzymescontrol efficiencyidentification
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