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Physiology and Biochemistry

Effect of Extracellular Metabolites from Gliocladium virens on Germination of Sporangia and Mycelial Growth of Pythium ultimum. Daniel P. Roberts, Biocontrol of Plant Diseases Laboratory, Plant Sciences Institute, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, MD 20705; Robert D. Lumsden, Biocontrol of Plant Diseases Laboratory, Plant Sciences Institute, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, MD 20705. Phytopathology 80:461-465. Accepted for publication 22 November 1989. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1990. DOI: 10.1094/Phyto-80-461.

Culture supernatants from Gliocladium virens grown in 5% bran extract or in minimal medium supplemented with autoclaved hyphae of Pythium ultimum inhibited sporangial germination and mycelial growth of P. ultimum. Culture supernatants from G. virens grown in 5% bran extract contained gliotoxin and laminarinase, amylase, carboxymethylcellulase, chitinase, and protease activities. Bran culture supernatants remained inhibitory after the above enzyme activities were inactivated by heating or removed by size-fractionation. Culture supernatants from G. virens grown in the supplemented minimal medium, which did not contain these enzyme activities, strongly inhibited sporangial germination and mycelial growth. The metabolite gliotoxin was the only substance that was present in the size-fractionated preparation that was inhibitory to sporangial germination and mycelial growth of P. ultimum.

Additional keywords: antibiotic, biocontrol, enzymes, soilborne diseases.