Identification,Fermentation Optimization and Determination of Nematicidal Activity of Biocontrol Bacterium Y26
To control the root-knot nematode disease in cucumber,a bacterial strain Y26 was isolated from cucumber rhizosphere soil in the laboratory.Bio-activity of fermentation broth against root-knot nematodes was determined.The corrected mortality rate of the second-stage juveniles treated with fermentation broth for 24 hours was 95.12%,and the relative inhibition rate of eggs hatching reached 83.51%after 48 hours of fermentation broth treatment,so strain Y26 can be used as a bacterial control resource for root-knot nematodes disease.Strain Y26 was identified as Bacillus pumilus by morphological observation and molecular identification.The optimized conditions for fermentation of strain Y26 by Plackett-Burma design and response surface analysis were corn flour 2.14%,bean cake flour 3%,K2HPO40.57%,MgSO4·7H2O 0.21%,cultural time 12 hours,pH 7.2,inoculation amount 2%,cultural temperature 28℃,and the media amount was 50 mL/250 mL.After fermentation optimization,the spore concentration was increased by 25.69%,the corrected mortality rate of 10%fermentation broth increased from 78.03%to 93.32%before optimization.The results showed that the activity of optimized Y26 fermentation broth root-knot nematodes was significantly increased and could be developed and applicated as a biological nematicide.
root-knot nematodeBacillus pumilusidentificationoptimization of fermentation conditions
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