Control of Aspergillus parasiticus by Cladosporium fulvum in rice and corn
1992
Lauzon, R.D.
Cultural and morphological studies indicate that a fungal isolate with characteristics typical of Cladosporium fulvum favorably grow on Potato Dextrose Agar as exhibited by a greater average growth rate of 1.65 mm/day. Room temperature as well as 32 deg C was favorable for the growth of the organism, but failed to grow at 40 deg C and refrigeration temperature. The organism preferred pH towards neutral as exhibited by a higher average growth rate of 2.21 mm/day. Antagonistic activity of Cladosporium fulvum against Aspergillus parasiticus was temporary for the first few days. A headstart of 5 days for Cladosporium fulvum completely inhibited the growth of Aspergillus parasiticus when plated in Potato Dextrose Agar and Malt Extract Agar. In Corn Dextrose Agar and Rice Dextrose Agar complete suppression of growth was possible when the headstart was 7 days. Inhibitory activity of Cladosporium fulvum was greater when plated in PDA and incubated at 32 deg C and room temperature. The organism is more antagonistic to Aspergillus parasiticus at neutral pH. Pigment was the active compound inhibitory to Aspergillus parasiticus. Inhibitory effect of the organism includes modifying the morphology of Aspergillus parasiticus. The pigment could be easily extracted using acidified solvent. Evaporation of solvent left a reddish brown residue which was stable to heat in acidic and alkaline conditions. The pigment was fungistatic to Aspergillus parasiticus but non-toxic to chick embryo and white mice as well. Treating rice and corn seeds with culture filtrate from Cladosporium fulvum greatly improved germination performance of treated seeds.
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