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Abstract
Aerobic enrichment at 30° in a medium containing either cis, cis- or cis, trans-muconic acid as the sole source of carbon and energy is a highly specific method for the isolation of Pseudomonas acidovorans from soil. Nutritional studies with previously isolated strains of P. acidovorans and P. testosteroni, none of which was selected for the ability to utilize muconates, show that nearly all strains of both these species grow readily and promptly with both cis isomers of muconic acid. This ability is absent from all fluorescent pseudomonads examined, despite the fact that they possess the requisite enzymic machinery. The fluorescent pseudomonads appear to be impermeable to the muconic acids, and can use them as substrates for growth only through a mutation that alters the permeability of the cell.
Studies with one strain of Pseudomonas acidovorans show that it synthesizes inducibly all the enzymes responsible for the conversion of catechol to β-ketoadipate, their synthesis being elicited by growth with either cis, cis- or cis, trans-muconate. Mutants of P. acidovorans defective in the synthesis of either β-ketoadipate enol-lactone hydrolase or β-ketoadipate succinyl-CoA transferase are unable to grow at the expense of cis, cis-or cis, trans-muconate; this confirms the role of the β-ketoadipate pathway in the dissimilation of these two substrates by P. acidovorans.
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