A study of purified pyorubrin produced by local Pseudomonas aeruginosa.

A study of more than one thousand strains of local P. aeruginosa was performed. These include the strains production of various pigments, methods of extraction and purification, the pigments activity and characteristics. Lately, we have reported a comprehensive study about the purified blue pyocyanine pigment. This paper displays a parallel study of a number of physical and chemical properties of the purified pink pigment, the pyorubrin, that is produced by our local collection of P. aeruginosa strains. This characteristics is useful for production of an active pigment purpose and is necessary in the pigment use as antibiotic, in addition of importance in developing the methods of strains identification. Such studies are important due to the biological significance of pyorubrin activity against other bacteria and in comparison with some known antibiotics; stability tests and MIC (minimum inhibitory concentration) measurements indicate that found isolates were of animal and food origin mainly.

A study of purified pyocyanine produced by Pseudomonas aeruginosa: properties and grouping.

A study of more than one thousand strains of Pseudomonas aeruginosa was performed. These were collected from different sources, i.e. humans, animals, environment and food. Cumulative results revealed the existence of three different groups of pyocyanine. The biological importance of grouping this pigment is due to its activity against other bacteria in comparison with other antibiotics such as cyanomycin produced by Streptomyces cyanoflavus. No such grouping or any other classification was found in the literature. Stability test and MIC (minimum inhibitory concentration) measurements revealed the priority of group (I); also isolates of animal origin were found preferable. This may be due to the resistance of strains isolated from animals to antibiotics especially to carbenicillin and gentamycine. Observations indicate differences in optical properties of the blue pigment, i.e. absorption centres in the UV region. Some differences in their physical properties were also noted.

Kinetics of haemolytic activity in Proteus strains.

Proteus species produces toxins and constitutes a causative agent of some chronic and recurrent infections. For the study of haemolytic activity and the production and inhibition kinetics, a total of 140 local isolates were diagnosed and examined by the general biochemical methods, and their ability of haemolysis were tested by both direct and indirect methods utilizing the enrichment procedure for all strains. Two antibiotics, erythromycin and keflex (cephalexin), were tested for the study of haemolysis inhibition and its kinetisc. Rof further study, examples of Proteus species were selected; the new approach was based on mixing procedure between P. aeruginosa (also pyocyanine) and Proteus species for inhibition of haemolytic activity. Spectrophotometric analysis were used parallel to these studies to support quantitatively the observed results as all samples show an absorption centre at 542 +/- 1 nm. Results of such analysis of haemolytic activity and inhibition kinetics are presented.

Collision cross section of fast beam by neutral gas target.

Effective deexcitation cross sections of fast beams of Na, Ne, and Li+ in the excited P state at energies of -160 keV with a N2 gas target are reported. These cross sections are obtained from analysis of the dependence of the effective lifetime on the gas pressure. Results for neon indicate small variations of deexcitation cross section for the different 3p fine structure levels.