For the purpose of removing nitrogen atoms from heavy oil by microbial procedures, the first approach was made to obtain microorganisms capable of degrading quinoline as the N-containing model compound by enrichment culture. One iso-late, identified as Pseudomonas putida Q26, was chosen for further study. The degrada-tion of quinoline by this strain yielded initially 2-hydroxyquinoline and then 8-hydroxycoumarin, resulting finally in the complete degradation. This strain was able to degrade quinoline and a few methylquinoline in a complex basic fraction of coal-liquids. It was observed that microbial treatment decreased nitrogen content of the basic fraction of hydrogenated recycle solvent derived from Taiheiyo coal.
