During the screening studies of antibacterial agents against Escherichia coli strains harboring episomes, namely F-lac-tet, R100, and T-kan, it was found that the strains carrying these episomes were more sensitive to macarbomycin than their original strains without episomes.
To evaluate the changes of the susceptibilities of Staphylococcus aureus and Escherichia coli clinical isolates over a four-year period from 1965 through 1968, we have conducted a series of studies. Results from these studies were used to assess the changes of bacterial sensitivities within groups of bacteria classified according to minimal inhibitory concentrations (MIC) values or having high sensitivity, intermediate sensitivity, or low sensitivity. We were able to compare changes in antibiotic activities more accurately by this technique than by our previous method of comparison of the averages of the MIC values only.
Phosphonomycin, (-)-cis-1, 2-epoxypropylphosphonic acid, was isolated from fermentation sources as a crystalline calcium salt. Methods for ion-exchange adsorption, ion-exchange chromatography using both anion- and cation-exchange resins, gel-permeation chromatography, adsorption chromatography and solvent partition were investigated. The overall purification was about 5, 000 fold with a yield of 12 %, Conditins for ion-exchange chromatography were developed based on batch equilibration studies. Thin-layer chromatography was used to develop a chromatographic procedure with alumina. The molecular weight estimated from gel-permeation studies was somewhat higher than the true value. A number of other salts which remained amorphous were also prepared.
An effective level of penicillin in serum of healthy individuals is maintained for 6, 8 and 10 hours after oral administration of single doses of 260, 325 and 385 mg of potassium penicillin G respectively. Regardless of variations of doses the antibiotic peak level is achieved one hour after oral administration. Palmitic acid stimulates serum protein and albumin binding of penicillin G. The increased binding of penicillin G with whole human serum in the presence of fatty acid is due to the influence of the latter on the albumin fraction of the serum. Dexamphetamine administration to healthy individuals produces a stimulation of penicillin binding by serum protein which is due to an increase of the free fatty acid (FFA) concentration in blood.
A new crystalline antibiotic named neopluramycin, which inhibits growth of Gram-positive bacteria, leukemia L-1210 in mice and Yoshida rat sarcoma cells in tissue culture, has been isolated from the cultured broth of a strain of Streptomyces pluricolorescens. It was obtained as orange crystals, and analytical data and molecular weight determination are consistent with the empirical formula C40H50N20O10. Neopluramycin resembles pluramycin A, but is differentiated by its antibacterial spectrum, toxicity, thin-layer chromatography, and infrared absorption spectrum.
During an antibiotic screening programme, a new biologically active complex was isolated from an unidentified Streptomyces, strain Ac6 5691), which was obtained from a garden soil in Calcutta, India. This antibiotic complex was found to contain two water-soluble active fractions of which the major one was designated as boseimycin. This commuication describes the isolation, purification and characterization of boseimycin. It was found to have a close relationship to the streptothricin group of antibiotics but was differentiated from them on the basis of its physico-chemical and microbiological properties.
During the screening for new antibiotics, a new antibiotic was isolated in crystalline form from the cultured broth of a StreptomycesStreptomyces, isolated from a soil sample collected in Okinawa. The structural studies revealed that this antibiotic was deoxynybomycin1), which had been already derived chemically from nybomycin2) by Rinehart et al. In this communication, characteristics of the strain, production, isolation, properties of this antibiotic, and the structural determination are reported.