Shukla O P
Appl Environ Microbiol. 1986 Jun;51(6):1332-42. doi: 10.1128/aem.51.6.1332-1342.1986.
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.
通过在喹啉上进行富集培养从污水中分离出的一株假单胞菌，利用一条涉及8-羟基香豆素的新途径代谢这种底物。在该微生物以喹啉为底物的早期生长过程中，2-羟基喹啉作为中间产物积累；进一步培养时，8-羟基香豆素作为主要代谢产物积累。2,8-二羟基喹啉和2,3-二羟基苯丙酸被鉴定为其他中间产物。1 mM亚砷酸钠对喹啉代谢的抑制导致丙酮酸积累，而5 mM亚砷酸钠的抑制则导致2-羟基喹啉作为主要代谢产物和2,8-二羟基喹啉作为次要代谢产物积累。香豆素不能被这种细菌用作生长底物，但以喹啉培养的细胞将其转化为2-羟基苯丙酸，后者不再进一步代谢。喹啉、2-羟基喹啉、8-羟基香豆素和2,3-二羟基苯丙酸能被适应喹啉的细胞快速氧化，而2,8-二羟基喹啉氧化非常缓慢。因此，这种假单胞菌中的喹啉分解代谢是通过分子的羟基化作用开始的，随后吡啶环断裂生成8-羟基香豆素，8-羟基香豆素再通过2,3-二羟基苯丙酸进一步代谢。
