Abstract
Growth of tubercle bacilli on media-containing egg or similar complex substances is inhibited! by contamination of the medium with either fungi or bacteria. This inhibition is apparently not specific but results from the production of protein split product, deprivation of oxygen, etc.
On simpler mediums (e.g. Long's) the picture is very different. While some fungi are unable to grow on those mediums, others grow freely. As a rule they do not interfere with the growth of the tubercle bacillus and may even favor it.
A search was made for fungi capable of producing antibiotic agents. The following technic was used.
An alundun capsule (20 × 2 cm, dense) was introduced into a 250 cc Erlenmeyer flask containing 100 cc of Long's medium. The fluid inside the capsule (±5 cc) was inoculated with the fungus under investigation, while the outside fluid was inoculated with a recently isolated strain of virulent tubercle bacilli. While a rapid and easy exchange of metabolic product occurred through the alundun wall, the coarse fungus filaments did not as a rule penetrate it and invade the outer fluid. In the few cases in which this happened, the filtrate from the fungus growth was tested for the presence of growth inhibiting substances.
Of a large number of fungi, recently isolated from a variety of sources, only one. a Fusarium, sp., inhibited growth of the tubercle bacillus.
The inhibiting substance passes through fritted glass filters and Mandler filters but is partially inactivated by passage through Seitz filters. The crude filtrate is active up to a dilution of 1/20 and withstands heating to 100° for 15 minutes without loss of activity.
Experiments are now in progress to isolate the active principle and determine its activity in vivo.
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