Initial reactions in the biodegradation of 1-chloro-4-nitrobenzene by a newly isolated bacterium, strain LW1

Bacterial strain LW1, which belongs to the family Comamonadaceae, utilizes 1-chloro-4-nitrobenzene (1C4NB) as a sole source of carbon, nitrogen, and e nergy. Suspensions of 1C4NB-grown cells removed 1C4NB from culture quids, a nd there was a concomitant release of ammonia and chloride. Under anaerobic conditions LW1 transformed 1C4NB into a product which was identified as 2- amino-5-chlorophenol by H-1 and C-13 nuclear magnetic resonance (NMR) spect roscopy and mass spectrometry, This transformation indicated that there was partial reduction of the nitro group to the hydroxylamino substituent, fol lowed by Bamberger rearrangement. In the presence of oxygen but in the abse nce of NAD, fast transformation of 2-amino-5-chlorophenol into a transientl y stable yellow product was observed with resting cells and cell extracts. This compound exhibited an absorption maximum at 395 nm and was further con verted to a dead-end product with maxima at 226 and 272 nm, The compound fo rmed was subsequently identified by H-1 and C-13 NMR spectroscopy and mass spectrometry as 5-chloropicolinic acid. In contrast, when NAD was added in the presence of oxygen, only minor amounts of 5-chloropicolinic acid were f ormed, and a new product, which exhibited an absorption maximum at 306 nm, accumulated.