Screening of Two Biocontrol Strains of Bacillus subtilis against Ginseng Soil-borne Disease and Their Antifungal Activities

[ Objective] The paper was to obtain biocontrol strains with good control effects against ginseng soil-borne disease through screening. [ Method] Dilu- tion plate method and plate confrontation culture method were used to isolate and screen biocontrol bacteria from the rhizosphere soil of diseased ginseng. The strains were identified through morphology, physiological and biochemical characteristics and 16S rDNA. [ Result ] With Rhizoctonia solani, Fusarium oxysporum and Fu- sarium solani as the indicator strains, two biocontrol strains B59 and X1 with strong antagonistic effects were screened from the rhizosphere soil of diseased ginseng in Tieli farm of Heilongjiang Province, and they were identified to be Bacillus subtilis. The inhibition rates of two biocontrol strains against eight different fungi were all greater than 90%. The primary study indicated that B59 and X1 strains could secrete antifungal active substances. [ Conclusion] Two biocontrol Bacillus subti- lis strains 1359 and X1 all had strong antagonistic effect against ginseng soil-borne disease, which had certain potential for development and utilization.

Antagonistic Effects of Sphingomonas and Pseudomonas aeruginosa on 4 Kinds of Pathogenic Bacteria of Ginseng

[Objectives]To explore effective biocontrol methods for diseases in the process of ginseng cultivation,and develop an efficient and environmentally friendly biocontrol agent.[Methods]In this study,2 strains were isolated from biogas slurry,and Cylindrocarpon destructans(XF),Fusarium solani(GF),Botrytis cinerea Pers(HM)and Alternaria panax Whetz(HB)were used as test materials.The strains were isolated and identified by dilution plate method,16S rDNA sequence identification method,confrontation culture method,filter paper method and ultraviolet spectrophotometer method,and the bacteriostatic activity and bacteriostatic rate were tested.[Results]Strain 15(Sphingomonas)and strain 19(Pseudomonas aeruginosa)were screened out through identification and analysis,and they grew stably within 8-10 d.The bacteriostatic rates of strain 15 against A.panax and B.cinerea were 47.37%and 43.40%,respectively,and the bacteriostatic rates of strain 19 against A.panax and B.cinerea were 62.30%and 63.27%,respectively.The bacteriostatic activity of the extract of strain 19 increased with the increase of OD_(600) value,and the bacteriostatic effect was optimal when the OD_(600) value was in the range of 0.8-1.0,up to 70%,so it had a strong biocontrol potential.[Conclusions]This experiment provides convenience for more effective inoculation,establishes a fast,simple and accurate method for the determination of the best bacteriostatic rate of P.aeruginosa culture solution to HM,and lays a foundation for large-scale culture of P.aeruginosa culture solution.Besides,it is expected to provide a theoretical basis for the efficient control of ginseng B.cinerea in field production,use it for the prevention and control of ginseng shoot diseases,and provide a reference for the efficient and diverse development of biocontrol agents for ginseng shoot diseases.