The effects of neopluramycin and bleomycins A2 and A6, functioning as antibiotics by binding to DNA, on the transcription of T4 phage were studied. Neopluramycin was observed to inhibit both in vivo and in vitro transcription of T4 phage. It also interfered with the development of infectious phage particles. Although bleomycins A2 and A5 did not significantly affect in vivo transcription of T4 phage, they inhibited the in vitro transcription, when the template phage DNA was incubated with the antibiotics for 10 minutes prior to the addition of RNA polymerase and nucleoside triphosphates. The RNAs synthesized in the presence of the antibiotics were smaller and seemed to contain larger ratio of pre-early RNA than the RNA synthesized in the absence of antibiotics. The results were in accordance with the assumption that the antibiotics inhibit RNA synthesis by binding to the template DNA and interfering with the elongation step of the RNA polymerase reaction. The RNA polymerase reaction, using calf thymus DNA as a template, was also inhibited by the antibiotics.
When using tissue culture as a tool for screening antitumor agents, most cell cultures were contaminated with mycoplasma and attempts were made to eliminate the mycoplasma from the cell cultures with antibiotics. Several strains of mycoplasma tested were highly sensitive to macrolide antibiotics and antitumor antibiotics. Among macrolide antibiotics, leucomycin group such as leucomycin, spiramycin and tylosin were more active than erythromycin group, such as erythromycin and oleandomycin. In contrast to the results in vitro, mycoplasma infected naturally in the cultured cells was highly resistant to the antibiotics, but mycoplasma (strain Campo) inoculated in embryonated eggs was completely eliminated with 2 injections of 40mcg/egg of leucomycin.
An antagonist of phenylalanine, L-1, 4-cyclohexadiene-1-alanine, was isolated from the culture broth of a strain of Streptomyces designated Streptomyces diastatochromogenes var. sakaii. It is active against plant-pathogenic fungi, and Pseudomonas aeruginosa on synthetic medium. Producing strain, and the production, isolation, identification and biological properties of this antibiotic are described.
Pseudomonas fluorescens KY 4032, when grown on n-paraffin (mixture of C12, C13 and C14 fractions) as the sole source of carbon, produced antibacterial substances in the culture medium. Two kinds of new substances named as fluopsins C and F, (C2H4NOS)2Cu and (C2H4NOS)3Fe, were isolated through the extraction of the culture broth with chloroform and the chromatography on silicic acid column. Fluopsin C contains copper atom in the molecule while fluopsin F does iron instead of copper. The biological activities of these compounds were remarkable against most of both gram-positive and gram-negative bacteria. For the production of these antibiotics by this microorganism, n-paraffin was the preferable carbon source. The production of fluopsin C was apparently dependent on the quantity of copper ion added to the culture medium. In the limited concentration of copper ion the major product was replaced by fluopsin F.
Two new antibiotics, fluopsins C and F, have been isolated from the culture broth of Pseudomonas fluorescens and characterized as bis(N-methyl-N-thioformylhydroxylaminato)copper(II) (I) and tris(N-methyl-N-thioformyl-hydroxylaminato) iron(III) (II) respectively.
Antibiotic 6640 is a new aminoglycoside antibiotic isolated from fermentation broths of a new species of the genus Micromonospora, named Micromonospora inyoensis. It has been differentiated from other known related antibiotics by a variety of chemical and biological methods. Its spectrum of activity appears to be quite similar to that of gentamicin in vitro and in vivo. The acute toxicity is approximately twice that of gentamicin in mice.
Antibiotic 6640 is produced by aerobic submerged fermentation of a new species of organism, Micromonospora inyoensis (NRRL 3292). The antibiotic is produced substantially as a single component and is extracted from the broth by a cationic exchange procedure. It is purified by use of an anionic resin. Chromatographic studies indicate that it most nearly resembles, but is different from gentamicin C1a. This report describes the production, isolation, , purification, and chemical and physical properties of antibiotic 6640.
Antibiotic 6640 has an in vitro spectrum similar to gentamicin with a potency equal to or twice that of gentamicin, particularly against Pseudomonas. Antibiotic 6640 is more active at an alkaline pH but is little affected by the presence of serum. MBC values are near MIC values. Antibiotic 6640 has up to 5 times the activity of gentamicin in therapeutic and prophylactic antibacterial tests in mice. Serum levels of the two antibiotics are similar in mice, rats and dogs. Results of comparative ataxia tests in cats are reported.