|Van Cauwenberge, James|
|Shea Andersh, Maureen|
Submitted to: International Plant Growth Promoting Rhizobacteria Workshop
Publication Type: Abstract Only
Publication Acceptance Date: October 10, 1997
Publication Date: N/A
Technical Abstract: Strain 2-79 is a biological control agent against take-all root disease of wheat. When strain 2-79 is delivered to the field in seed coatings, it can colonize the emerging root and produce phenazine-1-carboxylic acid (PCA) as its primary means of disease suppression. Barriers to the commercial use of phenazine-producing pseudomonads, such as strain 2-79, include the lack of liquid culture and formulation technologies needed to optimize cost-effective mass production and application. For example, there is little published information regarding the impact of the liquid culture phenazine productivity on the biocontrol qualities of the cell harvest, i.e., storage survival, efficacy, and phytotoxicity. In the current study, culture environments varying in temperature (25,31,34 deg C), pH (7 or 8), and sources of carbon (glucose, xylose, glycerol, fructose) were selected in order to induce a 0 to 1 g/L range of PCA accumulations. Our results indicated that increasing growth culture phenazine productivity was significantly correlated with increasing germination losses in stored seed treatments. The dry storage survival of the biocontrol agent did not vary significantly with the liquid culture conditions used to manipulate phenazine productivity. At least equivalent bioefficacy was achieved by cells grown with either low or high PCA productivities. Of the culture variables tested, only the 34 deg C condition yielded cell formulations which both preserved seed germination and increased disease suppression. For the case of take-all suppression, the design of the cell production process to eliminate accumulation of phytotoxic metabolites allows for efficient field delivery of phenazine-producing pseudomonads in seed coatings with full preservation of seedling emergence.