The regulation of naphthalene metabolism in pseudomonads

Shamsuzzaman, Kazi M. (1974) The regulation of naphthalene metabolism in pseudomonads. Masters thesis, Memorial University of Newfoundland.

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Abstract

Naphthalene oxygenase was induced in Pseudomonas NCIB 9816 when the organism was grown on salicylate, or on succinate and salicylate together. The enzyme was not induced when the organism was grown on catechol or on succinate and catechol. The levels of catechol, 1,2-dioxygenase and of catechol in extracts from cells that had been grown in the presence of salicylate were similar to those in extracts from cells that had been grown in the presence of catechol. These observations suggest that salicylate may be the inducer of naphthalene oxygenase. This is supported by the observations that when either 2-aminobenzoate or 2-hydroxybenzyl alcohol was added to cultures growing on succinate, naphthalene oxygenase was induced gratuitously. -- Salicylaldehyde dehydrogenase and salicylate hydroxylase were also induced in the organism under the same conditions as caused the induction of naphthalene oxygenase, but the levels of these three enzymes were not constant relative to one another under the different growth conditions. In spite of this lack of proportionality which may be due to the limitations of the methods used for the determinations of these enzyme activities, the observation that all three enzymes may be induced by a single gratuitous inducer suggests that these enzymes, and possibly all involved in the degradation of naphthalene to catechol, are controlled coordinately. -- Catechol 1,2-dioxygenase was induced in NCIB 9816 by catechol and salicylate, but not by the gratuitous inducers of naphthalene oxygenase. Catechol 2,3-dioxygenase levels in extracts from succinate grown organisms was comparable to that in extracts from cells induced with salicylate, catechol, 2-aminobenzoate or 2-hydroxybenzl alcohol. The synthesis of this enzyme therefore seems to be constitutive in Pseudomonas NCIB 9816.

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