ARS | Publication request: Pilot-scale production and stabilization of microsclerotia of the potential mycoherbicide Mycoleptodiscus terrestris using deep-tank fermentation and air-drying.

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: July 18, 2007
Publication Date: July 18, 2007
Citation: Jackson, M.A., Shearer, J.F., Heilman, M.A. 2007. Pilot-scale production and stabilization of microsclerotia of the potential mycoherbicide Mycoleptodiscus terrestris using deep-tank fermentation and air-drying [abstract]. Aquatic Plant Management Meeting. p. 39.

Technical Abstract: The fungus Mycoleptodiscus terrestris (Mt) is being developed as a bioherbicide for control of various invasive submersed aquatic plants including Hydrilla verticillata and Myriophyllum spicatum. A constraint to the commercial use of Mt as a bioherbicide is the development of an economic method for producing stable propagules of the fungus. Our previous studies with Mt identified novel nutritional conditions that supported the liquid-culture production of high concentrations of microsclerotia. Microsclerotia are compact, hyphal aggregates that often serve as overwintering structures for fungi. In order to scale the production process to commercial levels, pilot-plant fermentations have been conducted in 100-liter fermentors using a basal salts medium supplemented with 6 percent glucose and 3 percent corn steep liquor powder. Four-day fermentations yielded ~30 grams Mt biomass/liter with 65 percent of the biomass being well-formed microsclerotia. The microsclerotia-containing biomass was separated from the fermentation broth with a rotary drum vacuum filter, granulated, and air-dried on shallow trays to less than 5 percent moisture. Ninety percent of the dried microsclerotia germinated hyphally after 24 hours incubation on water agar plates and produced ~3 x 10**7 conidia/gram dried Mt microsclerotia after 8 days incubation at 28ºC. Dried microsclerotia produced and stabilized under pilot-scale conditions were shown to infect and kill hydrilla. Studies continue on optimizing fermentation conditions and drying protocols, and on identifying formulations for improving the biocontrol efficacy of Mt microsclerotia against hydrilla.