Submitted to: Weed Science Society of America Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 2/10/2005
Publication Date: 2/16/2005
Citation: Jackson, M.A., Shearer, J.F., Kargalioglu, Y., Heilman, M.A. 2005. Production and stabilization of microsclerotia of the bioherbicide Mycoleptodiscus terrestris produced using deep-tank fermentation [abstract]. Weed Science Society of America Meeting. Abstract #215. p. 65.
Technical Abstract: Hydrilla verticillata (L.f.) Royle (hydrilla) is considered one of the most important aquatic weeds in the world. Introduced into Florida in the 1950's, this invasive aquatic macrophyte is now found in lakes, ponds, reservoirs, rivers, and canals across the Southern United States. Mycoleptodiscus terrestris, an endemic fungal pathogen of hydrilla, has been identified as a potential biocontrol agent for this troublesome weed. Our previous studies with M. terrestris identified novel nutritional conditions that supported formation of highly melanized, microsclerotia in liquid culture. Mycoleptodiscus terrestris (Gerd.) Ostazeski microsclerotia were produced in high concentrations, survived air-drying, and remained stable as a dried powder when stored at 4 deg C. Furthermore, these microsclerotia infected and killed hydrilla when applied to the aquatic weed by germinating hyphally to infect the plant and also by producing infective conidia via sporogenic germination to provide a secondary infective structure. In order to scale the process to commercial production levels, pilot-plant fermentations have been conducted in 100-L fermentors using a basal salts medium supplemented with 4% glucose and 1% corn steep liquor powder. Seven-day fermentations yielded 17.8 g M. terrestris biomass/L with 65% of the biomass being well-formed microsclerotia. After air-drying to lower than 4% moisture, 75% of the microsclerotia germinated hyphally within 24 hours; and after 8 days' incubation on water agar plates, produced 3 x 107 conidia/g dried M. terrestris microsclerotia. Microsclerotia produced under these conditions were shown to be infective on hydrilla. These results have demonstrated that deep-tank fermentation can be used for the mass-production of stable, infective microsclerotia of M. terrestris for use in controlling hydrilla.