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.