Antibiotic Substances from Basidiomycetes: IV. Marasmius Conigenus.

In a survey of Basidiomycetes for antibacterial activity, Marasmius conigenus (No. 6890) was reported to inhibit the growth of Staphylococcus aureus when tested by the strip or the "hole" method.' Dr. W. H. Wilkins kindly supplied us with a subculture of this organism with which we continued studies. Other species of Marasmius produce antibacterial substances.2' 3 When grown on corn steep, thiamine peptone, or potato dextrose agar, and tested by the streak method,4' I Marasmius conigenus showed in our hands marked antibacterial activity against Staphylococcus aureus (H) slight activity against Escherichia coli and none for Mycobacterium smegma. Considerable activity against Staph. aureus was observed with discs4' 5 cut from fungous cultures grown on the three media. The position of the disc in relation to the fungous colony determined the size and character of the inhibition zone. The disc cut from the oldest part of the colony produced the largest inhibition zone which was clear near the disc and surrounded by a zone of partial inhibition. Discs cut at a distance of 20 mm. from the edge of the fungous colony gave zones of partial inhibition. Isolations from these zones have not yielded strains of Staph. aureus resistant to the antibacterial material from this fungus. Antibacterial Activity of Culture Liquids.-The fungus was grown at 25°C. in 2800-ml. Fernbach flasks containing beech shavings and a corn steep medium.6 In about four weeks, when the surface of the liquid was about one-half covered with mycelium, the activity of the culture liquid against Staph. aureus was 256 or 512 dilution units per milliliter. Reflooding such mats with fresh medium produced liquids of as high activity one week or more after reflooding. The culture liquid from a seven-