[Variations in the P. aeruginosa polysaccharide synthesis conditioned by aminosugars (author's transl)]

The production of capsular and extracellular polysaccharides by P. aeruginosa species was conditioned by the presence of hexosamines in the growth media. Glucosamine and most remarkably galactosamine, strongly reduced the production of extracellular polysaccharides. Studies on the dynamics of the polysaccharide production show that these products are used by the cells after the carbon source (glucose of glucosamine) of the growth medium has been exhausted. These results suggest the presence of adaptative hexosaminidases. The concentration of total hexosamines in the polysaccharides changed according to the carbon source (glucose, glucosamine or galactosamine) and so did the molecular composition as demonstrate by IR spectrometry. IR spectra show variations in the intensity of some characteristic bands, as those located at 1,650-1,560 cm-1 (N-acetyl-hexosamines), 1,420 and 1,320 cm-1 (aminosugars) and at 1,380 cm-1. This last band disappears from polysaccharides after prolonged incubation. Bands between 1,300 and 700 cm-1 varied and even disappeared according to the aminosugar employed and the length of the incubation period.