Isolation, screening and indoor control effect of biocontrol bacteria against Acanthopanax senticosus black spot

Objective In order to screen the bacteria with biological control potential against Acanthopanax senticosus black spot.

Method The bacteria with antagonistic effect against A. senticosus black spot were isolated and screened from the rhizosphere soil of healthy A. senticosus by plate confrontation method. The screened strains was classified and identified based on morphological, physiological, biochemical identification and 16S rDNA combined with gyrB sequencing analysis, and the antibacterial spectrum was determined. Its biocontrol potential was further evaluated through leaf colonization and pot control effect test.

Result A total of 419 strains of rhizosphere bacteria were isolated from A. senticosus. Among them, the strain YZ-375 was identified as Bacillus velezensis. Strain YZ-375 had good antagonistic effect against the black spot pathogen of A. senticosus, the inhibition rate of sterile filtrate was 65.85%. The strain YZ-375 had antagonistic effects against Rhizoctonia solani, Alternaria panax, Fusarium solani, Sclerotinia gingseng, Cylindrocarpon destructans and Fusarium oxysporum, with the inhibition rates from 69.21% to 77.44%. After 35 d of colonization in fresh leaves, the bacterial count of strain YZ-375 remained at 10³ CFU per gram of fresh leaves. The control effect of strain YZ-375 on black spot of A. senticosus reached 72.31%, which was not significantly different from that of Bacillus subtilis and difenoconazole.

Conclusion B. velezensis YZ-375 has good biocontrol potential and has certain development and application prospects.