Antifungal Metabolites from Submerged Culture of Ganoderna Lucidum (Polypore)
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Date
1991-06
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Addis Ababa University
Abstract
About 60 different basidiomycete cultures were screened for antimicrobial secondary metabolites
in submerged culture grown in four different media. Ten (17%) of them produced antimicrobial
secondary metabolites. Production medium, duration of growth, and the most susceptible test organisms
for each producing strain were established. Among basidiomycetes screened for antimicrobial activity,
the culture filtrate extract of the Ethiopian strain of the polypore, Ganodemw lucidum produced the
most effective antifungal compounds. The cu/~lral characteristics, growth in submerged culture of the
polypore and isolation methods of the two antifungal antibiotics are described. Medium A (Yeast extract
malt extract glucose medium) was a better medium for the production of the two antifungal agents.
These compounds were released to the culture fluid and the maximum amount of antifungal compounds
is obtained after 12 days of submerged growth at 120 revolution per minute (rpm). TIle two antifungal
metabolites (20lA and 201B) isolated from culture filtrated were biologically characterized. TIlese
metabolites had a wide spectrum of antifungal activity and affect the growth of several saprophytic as
well as pathogenic fungi. The minimal inhibitory concentration (MIG) of 20lA against Candida albicans
and Candida pseudotropicalis was less than 1 mcg/ml and 1-5 mcg/ml respectively. Inhibition diameter
zone of 36 mm was produced when 10 mcg/disc of 20lA was applied on agar medium seeded with
AspergHlus flavus. 20lA was also a potent inhibitor of spore gemlination. No spores of Aspergillus niger
were germinated at a concentration of 10 mcg/ml of the antibiotic. Bacteria were affected only at high
concentration.
Antibiotic 20lA was more active than antibiotic 201B. A comparison of antifungal activity against
dennatophytes showed that the efficacy of 20lA was comparable to griseofulvin. Treatment of sheep
erythrocytes with the two antifungal antibiotics up to 100 mcg/disc did not show any lytic effect on sheep
red blood cel/s. Application of 1 mg/1Ocm' of cn/de extract on a shaved rabbit skin showed no
demlatotoxic reactions.
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Biology