Biomedical subjects
Publications and source records attributed to E Armau.
CL307-24, a complex of new antibiotics has been isolated from the fermentation broth of Saccharopolyspora aurantiaca sp. nov. The complex was purified by cation-exchange and hydrophobic interaction chromatographies. It was then resolved as one major and three minor components by silica gel chromatography and HPLC.
A simple and selective screening method was developed for detecting new aminoglycoside (AMG) antibiotics from actinomycetes strains propagated on solid culture media. The first phase of the screening program is designed to isolate AMG-type activities using: 1) two Serratia marcescens strains, one susceptible and one resistant to AMGs, 2) the high tolerance of AMGs to heat in acidic solutions and 3) the specific resistance of a streptothricin producing strain of Streptomyces lavendulae to streptothricin antibiotics. The second phase of the screening program identifies already known AMG antibiotics through the characteristic spectrum of action which each AMG shows toward a group of bacterial strains synthesizing various AMG-inactivating enzymes.
Strains of Saccharomyces cerevisiae FL200 capable of growing on a solid medium containing a mixture of polyene macrolide antibiotics (nystatin, 40 micrograms/ml, amphotericin B, 40 micrograms/ml, pimaricin, 150 micrograms/ml and RP9971 antibiotic, 10 micrograms/ml) have been isolated after successive selection steps. The mutant strains, PR13 and PRC24, are 10 to 100 times more resistant than the polyene macrolide antibiotics. When 4% Tween 80 is added to the medium, resistance to these antifungal drugs is further increased. In addition, strain PRC24, derived from strain PR13, is resistant to a non-polyene macrolide antifungal antibiotic, cycloheximide. In contrast, PR13 and PRC24 are both highly susceptible to a large range of compounds, including non-polyenic antifungal, antitumor and antibacterial agents. These particular characteristics make these strains useful for the rapid detection of antifungal compounds of the polyene macrolide and cycloheximide types, as well as for the recognition of antimitotic substances.
A simple and selective assay system was developed in the search for new insecticidal substances from Actinomycetales strains propagated on solid culture media. The strains were first tested for their ability to produce antimicrobial compounds. Only strains displaying weak or no activity were retained and screened in the insecticidal bioassay. Microbial solid cultures were given as food to larvae and to adults of Musca domestica to detect insecticide producers. A second phase, after extraction of the active compounds, consisted of an evaluation of the insecticidal potency and a primarily biological identification of the products synthesized by the selected strain. Of 6,280 actinomycete strains which were screened, 47 were active but only 30 of these were finally chosen in the second phase of screening. All these strains, except one, produced known metabolites such as piericidins, avermectins or valinomycin. The one strain, CL307-24, and its insecticide products appeared novel and will be the topic of further study.
We undertook a microbiological study, in children, of dental plaque from sound surfaces or associated with rampant caries, both black-colored and unstained. Improved selective media allowed for the enumeration of bacteria belonging to specific genera or species present in plaque samples. A nearly similar bacterial distribution was found in both types of rampant caries. Aciduric flora, Streptococcus mutans, Veillonella, and Lactobacillus predominated in plaque over the lesions, whereas extracellular polysaccharide-producing streptococci other than S. mutans, as well as Actinomyces, were more abundant in plaque from sound surfaces. However, more lactobacilli and Actinomyces were recovered from pigmented lesions than from the unstained ones. These findings suggest that the microbial flora associated with black-pigmented lesions did not strongly differ from that observed over unstained caries lesions.