Several cephalosporin derivatives were classified into three groups based on their degradation by bacteria. Different properties of m-Br-PACA and α-Ph-POCA with respect to microbial degradations were also found with other clinically isolated strains of Staph. aureus and E. coli. The antibacterial activity of cephalosporin derivatives is related to degradation by Staph. aureus No. 33, but not that by E. coli No. 11.
Bleomycin was observed to inhibit DNA and protein syntheses in intact Escherichia coli, Ehrlich carcinoma and HeLa cells. DNA synthesis was more profoundly affected than protein synthesis. RNA synthesis was not significantly suppressed by the antibiotic. The activity of bleomycin was highly dependent on the number of cells and on the concentration of phosphate in the medium, being more pronounced at low concentration of phosphate and with fewer cells. Bleomycin complex, copper-free bleomycin A2, copper-chelating bleomycin A2 (Cu 2.6 % w/w) and copper-saturated bleomycin A2 (Cu 5.1 %) were studied. All of them exhibited substantially the same activity. Bleomycin caused elongation of E. coli cells and enlargement of HeLa cells, with a reduction in the number of mitotic figures of growing HeLa cells, indicating that the antibiotic interfered with the mitotic process.
The structural requirements for the microbial transformation of 2-aminoimidazoles to 2-nitroimidazoles by Streptomyces strain LE/3342 have been investigated. Substrates carrying an alkyl group in position 4 (or 5) were oxidized, the efficiency decreasing with the increase of the length of the chain. Lower yields in the oxidation were observed with the 4, 5-dimethyl derivative. When a methyl group in position 1 or a phenyl group in position 4 (or 5) was present no transformation product could be detected. The influence of the substrate concentration and the time course of the transformation are reported and discussed.
Streptomyces antibioticus producing antimycin A and actinomycin did not fit in cell-wall types of aerobic actinomycetes. In addition to universal actinomycetes cell-wall components, i. e. glucosamine, muramic acid, glutamic acid and alanine, diaminopimelic acid (DAP), lysine, leucine (isoleucine), glycine, arabinose, glucose, galactose and mannose were detected as major constituents.Phase of the life-cycle influenced the distribution of serine, aspartic acid, lysine and DAP isomers. LL-DAP was found rather than meso form. Meso-DAP was consistently revealed after 48 hr incubation and not at other times, and as distinct from LL was not strict alternative with lysine. The occurrence of meso-DAP, relatively small amounts of murein glucosamine (2.2-5.5 %) and lysozyme resistance suggest a similarity to nocardiae cell-walls. Decrease of murein hexosamine was unfavourable for antimycin A yields. Variation of the murein amino acids stimulated production of actinomycin.
An agar diffusion method for testing antibiotics and other chemicals inhibiting Mycoplasma species has been developed. Paper discs dipped in solutions of the candidate compounds are placed on agar plates heavily seeded with Mycoplasma cells. After over-night incubation, the agar surface is flooded for 5 minutes with a 2, 6-dichlorophenolindophenol solution. The viable cells reduce the dye while the killed cells do not. Dose response curves with slopes between 3 and 4 were obtained when discs containing chloramphenicol, chlortetracycline, or tylosin were placed on agar seeded with Mycoplasma laidlaxvii type B. The technique can also be used for preparing bioautographs of paper or thin layer chromatograms.
A new antibiotic polyetherin A was isolated from cultures of Streptomyces hygroscopicus strain E-749. The antibiotic is active against Gram positive bacteria including mycobacteria, and phytopathogenic fungi. The substance is obtained as colorless needles, m. p. 183.5-185°C, and is a lipophilic acid with the molecular formula C42-43H72-74O12.It is dextrorotatory active and has no absorption in the ultraviolet and visible regions. The infrared and n. m.r. spectra of the antibiotic and some derivatives revealed a carboxyl, a methoxyl and two vicinal hydroxyl groups but no carbonyl function. This information suggested polycyclic polyether structure for the antibiotic.
During production of kasugamycin, 15N-glycine was added, yielding 15-Nkasugamycin. 15N-Kasugamycin was treated with baryta, yielding ammonia f rom the carboxyformidoyl group (the side chain). The two amino groups of kasuganobiosamine which was obtained by baryta treatment were degraded to ammonia. Mass spectroscopic analysis of ammonia from these two sources showed that the nitrogen atom of glycine is incorporated into the imino nitrogen of the carboxyformidoyl group.
The biosynthesis of kasugamycin was studied with the purpose of increasing the fermentation yield of kasugamycin. Kasugamycin was stable in the cultured broth, if pH of the cultured liquid did not exceed 8.0. Kasugamycin in the cultured broth was proved to show no inhibition of kasugamycin production. Glucose and glycine added to the medium during kasugamycin production were rapidly metabolized. In parallel with the rapid disappearance of these compounds, they were incorporated into kasugamycin, but their metabolic products were not used for synthesis of kasugamycin. Myo-inositol was slowly consumed and incorporated into kasugamycin. There was 26 % left in the medium 200 minutes after addition of myo-inositol. Thus, it was suggested that myo-inositol added caused some change in utilization of this compound. Among 3-day, 6-day and 10-day cultured broths, the incorporation of 14C-glucose, 14C-glycine and 14C-myo-inositol were the highest in the 3-day culture broth. 14C-Glucose and 14C-myo-inositol were equally well incorporated at pH 5.0-7.5 but the highest incorporation of 14C-glycine was shown at pH 6.5-7.0. Optimal temperature for incorporation of 14C-glucose, 14C-myo-inositol and 14C-glycine was found to be dependent on the grade of aeration.
Induced enzymes in Actinoplanes missouriensis convert actinomycins to the monolactone and to actinomycinic acid. These enzymes are induced by adding actinomycin, actinomycin monolactone, and peptide derivatives of 4-methyl-3-hydroxyanthranilic acid to washed cell systems. Among the compounds which do not induce these enzymes are the peptide portion of actinomycin, actinomycinic acid, and the heterodetic peptide antibiotics etamycin, vernamycin B, and albomycin. The biosynthesis of the actinomycin degrading enzymes induced by addition of actinomycin was inhibited by simultaneous addition to the washed cells of chloramphenicol, tetracycline, neomycin, streptomycin, KCN, or Ag2SO4.