Radiolabelling patterns in alginate of Pseudomonas aeruginosa synthesized from specifically-labelled 14C-monosaccharide precursors.

Incorporations of radioactivity in alginate from specifically-radiolabelled glucose molecules by a parental strain and a gluconate-negative mutant of Pseudomonas aeruginosa were compared. The gluconate-negative mutant, which was deficient in the Entner Doudoroff pathway enzymes, produced less alginate than did the parental strain. The ratio of incorporation of radiolabel from [6-14C] versus [1-14C] glucose was 9.7:1 in the parental strain, implying that the carbon skeleton is catabolised via the Entner Doudoroff pathway. In comparison, a ratio of 1.5:1 was obtained for the mutant. Analysis of the alginate produced after growth on [6-14C] glucose showed that in both strains less radiolabel was present in carbon-6 of the constituent uronic acids than would be predicted (parental strain 8.4% and mutant 38.3% of the expected values). These results imply that TCA cycle intermediates are probably the major precursors of alginate in P. aeruginosa.