Narbad A, Russell N J, Gacesa P
Department of Biochemistry, University College, Cardiff, Wales, Great Britain.
Microbios. 1988;54(220-221):171-9.
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.
比较了铜绿假单胞菌的亲代菌株和葡萄糖酸盐阴性突变体对特定放射性标记葡萄糖分子中放射性在藻酸盐中的掺入情况。缺乏恩特纳-杜德洛夫途径酶的葡萄糖酸盐阴性突变体产生的藻酸盐比亲代菌株少。在亲代菌株中，来自[6-¹⁴C]葡萄糖与[1-¹⁴C]葡萄糖的放射性标记掺入比例为9.7:1，这意味着碳骨架是通过恩特纳-杜德洛夫途径进行分解代谢的。相比之下，突变体的比例为1.5:1。对在[6-¹⁴C]葡萄糖上生长后产生的藻酸盐进行分析表明，在两种菌株中，组成糖醛酸的碳-6中存在的放射性标记都比预期的少（亲代菌株为预期值的8.4%，突变体为38.3%）。这些结果表明，三羧酸循环中间体可能是铜绿假单胞菌中藻酸盐的主要前体。
