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PubMedDate not supplied

Growth and cellulase production of Micromonospora chalcae and Pseudonocardia thermophila.

Beta(1,4)glucosidases and carboxymethylcellulases were demonstrated in both strains when using carboxymethylcellulose as a carbon source for growth. Beta(1,4)Glucosidases appeared mainly as cell-bound activities, whereas carboxymethylcellulases were evenly distributed between the incubation fluids and the cellular fractions. In both microorganisms, glucose appeared to repress biosynthesis of the enzymes, and cellobiose and carboxymethylcellulose acted as inducers of the cellulase complex.

Actinomycetales↗
PubMed1998

Analysis of sisomicin binding sites in Micromonospora inyoensis cell wall.

Sisomicin binding sites are located in the cell wall. They are the carboxyl groups of peptidoglycans, which are major components of the cell wall. The carboxyl groups have negative charges which can bind the positively charged amino groups of sisomicin. When the negative charges of the carboxyl groups of the peptidoglycans are changed to neutral or positive charges, sisomicin does not bind to the cell wall. Magnesium ions bind to the cell wall in competition with sisomicin, and have a weak affinity for the cell wall binding sites compared with sisomicin. The binding molar ratio of sisomicin to magnesium ions was approximately 1 to 10.

Anti-Bacterial Agents↗
PubMed1975

BL-P1654: a bacteriostatic penicillin?

In tube dilution studies, large discrepancies between inhibitory and bactericidal concentrations of BL-P1654 against Pseudomonas were observed. To explain these discrepancies which were not observed with carbenicillin, the kinetics of bacterial killing by these two penicillins were evaluated and compared. The kinetics of bacterial killing by both antimicrobial agents were characteristic of a penicillin, with killing initiating simultaneously with growth. Kill curves revealed the presence of a small number of cells resistant to BL-P1654 which were not detectable macroscopically. Studies on microbial resistance also showed the presence of a small but consistent number of cells resistant to BL-P1654 over a broad range of concentrations above its minimal inhibitory concentration. This pattern of resistance was not observed with carbenicillin. Thus, the discrepancies between inhibitory and bactericidal concentrations of BL-P1654 were not due to any unusual bacteriostatic activity but rather due to a small number of resistant cells whose presence could be detected only by sensitive subculturing techniques.

Carbenicillin↗
PubMed1976

Micromonospora-produced gentamicin components.

After the chromatographic separation of [methyl-(14)C]gentamicin major (C) components from a large-scale radioactive fermentation (Lee et al., 1974), [methyl-(14)C]gentamicin minor (polar) components (A, B, B(1), X(2), and G-418) were isolated from subsequent chromatography of the remaining antibiotic mixture. When l-[methyl-(14)C]methionine was added at the onset of biosynthesis of the gentamicin components, incorporation of label into the minor components preceded incorporation into the major components. Degradation occurred when [methyl-(14)C]gentamicin major components (C(1), C(2) and C(1)a) were added respectively to the gentamicin-producing culture medium and shaken.

Biodegradation, Environmental↗