Scorodonin (1), a novel biologically active metabolite, was isolated from submerged cultures of the mushroom Marasmius scorodonius (FR.) FR. Its structure has been determined by chemical and physical methods. The antibiotic inhibits the growth of bacteria, yeasts, and filamentous fungi. In cells of the ascitic form of EHRLICH carcinoma the incorporation of thymidine and uridine into DNA and RNA is strongly inhibited by scorodonin whereas the incorporation of leucine into protein is not affected.
A new sesquiterpene antibiotic, heptelidic acid, was found in the culture filtrate of three different strains of fungi isolated from soil samples. These strains were identified as Gliocladium virens, Chaetomirum globosum and Trichoderma viride. Heptelidic acid was produced by conventional submerged culture and purified by successive column chromatography on silica gel and Sephadex LH-20 and finally by preparative TLC on silica gel. The molecular formula of heptelidic acid was determined as C15H20O5 on the basis of elementary analysis and high resolution mass spectrometry of its monomethyl ester. The antimicrobial spectrum of the antibiotic revealed its specific activity against anaerobic bacteria, especially against Bacteroides fragilis.
Streptomyces noboritoensis KM-2753, an elasnin-producing strain, co-produces an antimycin complex and its elasnin productivity is low (0.006mg/ml). To obtain mutants possessing higher degrees of elasnin productivity and deficient in antimycin production, the strain was treated with N-methyl-N'-nitro-N-nitrosoguanidine (NTG), ultraviolet light, acriflavine (AF) and high temperature. Mutant N-134 obtained by treatment with NTG was 108 times higher than the original strain in elasnin productivity and produced no antimycin. Strain AF-17 obtained by AF treatment and strain H-80 obtained by incubation at high temperature showed 715 and 428 times higher productivities than that of the original strain, respectively. The productivity of elasnin was further increased 1.6-2.6 times by addition of saturated fatty acids, especially lauric acid, to the culture. Consequently, strain AF-17 produced 11.1mg/ml of elasnin in the presence of 10μg/ml of lauric acid.
The degeneration of bicyclomycin-producing strains of Streptomyces sapporonensis resulted in sharply depressed bicyclomycin formation in a large scale fermentation. Degenerated strains, whose productivities were only 1/30 to 1/100 of normal strains, could not form aerial mycelia on glucose-BENNETT's agar; they were aerial mycelia negative strains (am-). Repeated transfers of culture, treatment of mycelia with acriflavin, mechanical agitation shock on mycelia or higher growth conditions stimulated the degeneration of producing strains, suggestin the involvement of extrachromosomal elements or plasmids in biosynthesis of bicyclomycin. Shake flask fermentations inoculated with a mixture of a normal high-producing strain and a degenerated low-producing strain resulted in sharply depressed bicyclomycin formation in proportion to the increase of low-producing strain added. It appears that the low-producing strain outgrew the high-producing strain.
The biosynthesis of bicyclomycin by Streptomyces. rapporonensis was studied using suspensions of washed mycelium. Nicotinamide and Fe2+ were found to be essential cofactors in the biosynthesis. Production of bicyclomycin was enhanced most effectively in the presence of equal moles of L-leucine and L-isoleucine, which in experiments with radioactively labeled compounds were found to be incorporated into bicyclomycin at equivalent rates. These facts strongly suggest that bicyclomycin biosynthesis involves coupling of equal moles of these two amino acids.
The effects of oleficin, a polyene antibiotic of the nonmacrolide type, on isolated rat liver mitochondria were studied. Oleficin at a concentration of about 10 nmoles/mg protein increases both the rate of state 4 respiration and the "basal" ATPase activity of mitochondria. In contrast to this it inhibits the rate of both state 3 and uncoupled respiration and the DNP-stimulated ATPase activity. These inhibitions can be prevented by low concentrations (2-5mm) of magnesium ions. Oleficin induces a high amplitude swelling of non-respiring mitochondria in the isoosmotic nitrate and chloride solutions of K+, Na+, Tris+, Tea+ or Mg2+. In contrast to that it does not induce swelling of mitochondria treated with ruthenium red in isoosmotic calcium acetate. Indirect evidence suggests that oleficin increases also the proton permeability of the inner membrane. The swelling observed in the isoosmotic solutions of monovalent cations can he prevented by low concentration (2-5mm) of Mg2+. In the presence of the antibiotic Mg2+ and Ca2+ but not K+ and Na+, are transferred from an aqueous phase into a butanol-toluene bulk phase. Oleficin depletes Mg2+ and Ca2+ from mitochondria in a concentration dependent manner. Complete depletion of Mg2+ occurs only in the presence of EDTA, while that of Ca2+ does not need the chelator. It is concluded that the effects of oleficin on mitochondrial functions can be explained on the basis of an increase of the inner membrane permeability as the consequence of the depletion of Mg2+ from mitochondria caused by the antibiotic.
A new semisynthetic culture medium was prepared and found to serve many useful purposes in chemotherapeutical research and also in diagnostic microbiology. It contains 0.5% peptone, 0.1% glucose and is supplemented with 10% MCILVAINE's buffer. The medium is pH-stable and, being almost colorless, it is suitable for turbidimetric studies and enzymatic experiments which involve color-changes. For in vitro chemotherapeutic experimental studies it is a useful medium and, in certain cases, it behaves like an almost antagonist-free medium. Used as broth or in agar-base, it supports the growth of all of the 280 clinically important strains studied, including aerobic bacteria, Candida and Trichophyton. It promotes the germ tube formation of C. albicans and C. stellatoidea.