C-13 NUCLEAR-MAGNETIC-RESONANCE STUDIES OF PSEUDOMONAS-PUTIDA FATTY-ACID METABOLIC ROUTES INVOLVED IN POLY(3-HYDROXYALKANOATE) SYNTHESIS

The formation of poly(3-hydroxyalkanoates) (PHAs) in Pseudomonas putid a KT2442 from various carbon sources was studied by C-13 nuclear magne tic resonance spectroscopy, gas chromatography, and gas chromatography -mass spectroscopy. By using [1-C-13]decanoate, the relation between b eta-oxidation and PHA formation was confirmed. The labeling pattern in PHAs synthesized from [1-C-13]acetate corresponded to the formation o f PHAs via de novo fatty acid biosynthesis. Studies with specific inhi bitors of the fatty acid metabolic pathways demonstrated that beta-oxi dation and de novo fatty acid biosynthesis function independently in P HA formation. Analysis of PHAs derived from [1-C-13]hexanoate showed t hat both fatty acid metabolic routes can function simultaneously in th e synthesis of PHA. Furthermore, evidence is presented that during gro wth on medium-chain-length fatty acids, PHA precursors can be generate d by elongation of these fatty acids with an acetyl coenzyme A molecul e, presumably by a reverse action of 3-ketothiolase.