Degradation of quinoline by a soil bacterium

From garden soil a bacterium was isolated which grew aerobically in mineral salts medium with quinoline as sole C source and NH4+ as N source. During growth with quinoline, 2-hydroxyquinoline accumulated in the culture fluid and later disappeared. Whole cells oxidized 2-hydroxyquinoline, 2,6-dihydroxyquinoline and 2,7,8,-trihydroxyquinoline as rapidly as quinoline and without a lag. Catechol was oxidized more slowly by meta-cleavage but at an increasing rate indicative of adaptation. A number of derivatives of benzene and pyridine were not attacked. Whole cells oxidized 2,7,8,-trihydroxyquinoline to a yellow meta-cleavage product which was not further degraded. The following pathway is proposed: quinoline leads to 2-hydroxyquinoline leads to 2,6-dihydroxyquinoline leads to a trihydroxyquinoline (probably not the 2,7,8-compound, but possibly the 2,5,6-compound).