A Pseudonas sp. Isolted from sewage by enricument culture on quinoline metabolized this substrate by a novel pathway invovig S-hydroxycoumarinb During early growth of the organism on quinoline, 2kydroxyquhmline accua tas the intermediate; 8-hydroasycoumnrin accumulated as the major metabolite on further incebaten. 2,S-Dlydroxyquiollne and 2,3-dihydroxyphenylprophinic acid were identified as the other intermediates. Iidbition of quinole metabolism by 1 mM sodium arsenite led to the accumulation of pyruvate, whereas inhbiton by 5 atM arseiti resuled in the accumulation of 2-hydroxyquinoline as the major metaboiNte and 2,-Ehydroxyquine as the minor metabolite. Coumarin was not utilized as a growth substrate by this bacteriin, but quindlinegrown cells converted it to 2-hydroxyphenylpropionic acid, which was not further metaholzed. Quinoline, 2-hydroxyqalnoline, 8-hydroxycoumarin, and 2,3-dihydroxyphenylproplonke acid were rapidly oxidized by quinoline-adapted cells, whereas 2,8-dihy-diroxyquinoNne was oxidized very slowly. Quinoline catabolism in this Pseudomonas sp. is therefore initiated by hydroxylation(s) of the nolecule followed by cleavage of the pyridine ring to yield 8-hydroxycoumgrin, which is further metabolized via 2,3-dihydroxyphenylpropioniic acid.

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