The Bacterial Degradation of 5-Amino-4-chloro-2-phenyl-3(2H)-pyridazinone.

1. From the culture me,urn of bacteria, which utilize 5-amino-4-chloro-2-phenyl-3(2H)pyridazinone (pyrazon) as sole source of carbon four metabolites could be isolated. These metabolites were identified as 5-amino-4-chloro-2-(2,3-cis-dihydroxycyclohexa-4,6-diene-1-yl)-3(2H)pyridazinone (compound I), as 2-(5-amino-4-chloro-3-oxo-2,3-dihydro-2-pyridazino)-cis,cismuconic acid (compound II), as 2-pyrone-6-carboxylic acid (compound III) and as 5-amino-4-chloro-3(2H)-pyridazinone (compound IV). 2. Cell-free extracts of the pyrazon-degrading bacteria were shown to metabolize 2-hydroxymuconic acid with a stoichiometric release of CO2. 3. A pathway for the bacterial degradation of 5-amino-4-chloro-2-phenyl-3(2H)-pyridazinone is proposed. [ABSTRACT FROM AUTHOR]