title: Antagonistic Bacillus species as a biological control of ginseng root rot caused by Fusarium cf. incarnatum.
abstract: BACKGROUND
  This study aimed to develop a biocontrol system for ginseng root rot caused by Fusarium cf. incarnatum.
  
  
  METHODS
  In total, 392 bacteria isolated from ginseng roots and various soils were screened for their antifungal activity against the fungal pathogen, and a bacterial isolate (B2-5) was selected as a promising candidate for the biocontrol because of the strong antagonistic activity of the bacterial cell suspension and culture filtrate against pathogen.
  
  
  RESULTS
  The bacterial isolate B2-5 displayed an enhanced inhibitory activity against the pathogen mycelial growth with a temperature increase to 25°C, produced no pectinase (related to root rotting) and no critical rot symptoms at low [10(6) colony-forming units (CFU)/mL] and high (10(8) CFU/mL) inoculum concentrations. In pot experiments, pretreatment with the bacterial isolate in the presumed optimal time for disease control reduced disease severity significantly with a higher control efficacy at an inoculum concentration of 10(6) CFU/mL than at 10(8) CFU/mL. The establishment and colonization ability of the bacterial isolates on the ginseng rhizosphere appeared to be higher when both the bacterial isolate and the pathogen were coinoculated than when the bacterial isolate was inoculated alone, suggesting its target-oriented biocontrol activity against the pathogen. Scanning electron microscopy showed that the pathogen hyphae were twisted and shriveled by the bacterial treatment, which may be a symptom of direct damage by antifungal substances.
  
  
  CONCLUSIONS
  All of these results suggest that the bacterial isolate has good potential as a microbial agent for the biocontrol of the ginseng root rot caused by F. cf. incarnatum.
authors.affiliation: Department of Agricultural Biotechnology and Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul, Korea.
authors.forename: Minjae
authors.initials: M
authors.lastname: Song
authors.affiliation: Department of Agricultural Biotechnology and Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul, Korea.
authors.forename: Hye Young
authors.initials: HY
authors.lastname: Yun
authors.affiliation: Department of Agricultural Biotechnology and Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul, Korea.
authors.forename: Young Ho
authors.initials: YH
authors.lastname: Kim
keywords: Bacillus species; Fusarium cf. incarnatum; Panax ginseng Meyer; biological control; ginseng root rot
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