title: Microbial transformation of quinoline by a Pseudomonas sp.
abstract: A Pseudomonas sp. isolated from sewage by enrichment culture on quinoline metabolized this substrate by a novel pathway involving 8-hydroxycoumarin. During early growth of the organism on quinoline, 2-hydroxyquinoline accumulated as the intermediate; 8-hydroxycoumarin accumulated as the major metabolite on further incubation. 2,8-Dihydroxyquinoline and 2,3-dihydroxyphenylpropionic acid were identified as the other intermediates. Inhibition of quinoline metabolism by 1 mM sodium arsenite led to the accumulation of pyruvate, whereas inhibition by 5 mM arsenite resulted in the accumulation of 2-hydroxyquinoline as the major metabolite and 2,8-dihydroxyquinoline as the minor metabolite. Coumarin was not utilized as a growth substrate by this bacterium, but quinoline-grown cells converted it to 2-hydroxyphenylpropionic acid, which was not further metabolized. Quinoline, 2-hydroxyquinoline, 8-hydroxycoumarin, and 2,3-dihydroxyphenylpropionic acid were rapidly oxidized by quinoline-adapted cells, whereas 2,8-dihydroxyquinoline was oxidized very slowly. Quinoline catabolism in this Pseudomonas sp. is therefore initiated by hydroxylation(s) of the molecule followed by cleavage of the pyridine ring to yield 8-hydroxycoumarin, which is further metabolized via 2,3-dihydroxyphenylpropionic acid.
mesh_terms: D001711:Biotransformation; D003374:Coumarins / Q000378:metabolism; D003470:Culture Media; D006912:Hydroxyquinolines / Q000378:metabolism; D015125:Oxyquinoline / Q000031:analogs & derivatives / Q000378:metabolism; D010666:Phenylpropionates / Q000378:metabolism; D011549:Pseudomonas / Q000254:growth & development / Q000378:metabolism*; D011804:Quinolines / Q000378:metabolism*
chemical_list: D003374:Coumarins; D003470:Culture Media; D006912:Hydroxyquinolines; D010666:Phenylpropionates; D011804:Quinolines; C049535:2,8-dihydroxyquinoline; C049536:8-hydroxycoumarin; D015125:Oxyquinoline; C049534:2,3-dihydroxyphenylpropionic acid