Monday, August 11, 2008
P58

THE PRODUCTION OF FUNGAL MICROSCLEROTIA IN LIQUID CULTURE

Mark A. Jackson1, David A. Schisler1, Judy F. Shearer2, Stefan T. Jaronski3, and C. Doug Boyette4. (1) National Center for Agricultural Utilization Research, USDA - Agricultural Research Service, 1815 N University St, Peoria, IL 61604, (2) Engineer Res and Dev Ctr - Waterworks Experiment Station, U.S. Army Corps of Engineers, 3909 Halls Ferry Rd, Vicksburg, MS 39180, (3) Northern Plains Agricultural Research Laboratory, USDA - Agricultural Research Service, 1500 N Central Ave, Sydney, MT 59270, (4) National Biological Control Laboratory, USDA - Agricultural Research Service, Stoneville, MS 38776

A liquid culture production method has been developed for small sclerotia (microsclerotia) of various biological control fungi. The mycoherbicides Colletotrichum truncatum and Mycoleptodiscus terrestris and the mycoinsecticide Metarhizium anisopliae have all been shown to produce microsclerotia under appropriate nutritional and environmental conditions using liquid culture fermentation. Highly aerated fermentations of 4-8 days produced 0.5-50.0 x 106 microsclerotia l-1. In general, carbon-rich media supported the production of the highest concentrations of microsclerotia.  Depending on the biocontrol fungus, 80-95% of the microsclerotia survived air-drying to less than 7 % moisture with a shelf-life of 9-48 months at 4C. When hydrated and incubated at 28C, air-dried microsclerotia germinated hyphally and/or sporogenically. For weed or insect control, the soil incorporation of microsclerotial propagules delivered stable fungal propagules that produced infective conidial inoculum in situ. Additionally, the use of liquid culture fermentation to produce sclerotia in liquid culture will provide researchers a tool to study sclerotial morphogenesis and physiology under gnotobiotic conditions or allow large quantities of fungal sclerotial biomass to be produced so that novel compounds, such as antibiotics and insecticidal compounds that contribute to the persistence of sclerotia in soil, may be identified and mass produced.

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