title: The bacterial oxidation of N-methylisonicotinate, a photolytic product of paraquat.
abstract: Two bacteria have been isolated that are capable of oxidizing N-methylisonicotinate, a photodegradation product of Paraquat (1.1'-dimethyl-4,4'-bipyridylium ion). N-Methylisonicotinate-grown cells of strain 4C1, a Gram-positive rod, oxidized 2-hydroxy-N-methylisonicotinate without lag. Cell-free extracts of these cells converted 2-hydroxyisonicotinate into 2,6-dihydroxyisonicotinate; the reaction did not require molecular oxygen. Maleamate was deamidated and maleate isomerized to fumarate by soluble enzyme systems. [(14)C]Formaldehyde was isolated as the dimedone derivative from the supernatant of a cell suspension oxidizing N-[(14)C]methylisonicotinate, and no [(14)C]-methylamine was detected. Whole cells incubated with N-methyl[carboxy-(14)C]isonicotinate released 95% of the radioactivity as (14)CO(2). The second bacterium, strain 4C2, a Gram-negative rod, did not oxidize any of the mono- or di-hydroxypyridines or their N-methyl derivatives that were available or could be synthesized; nor did cell-free extracts oxidize any of these compounds. Methylamine was oxidized by whole cells without lag; cell-free extracts converted methylamine into formaldehyde when a soluble enzyme system requiring an electron acceptor was used; formaldehyde was oxidized to formate and formate to CO(2) by enzyme systems requiring NAD(+).
mesh_terms: D001419:Bacteria / Q000378:metabolism*; D002245:Carbon Dioxide / Q000096:biosynthesis; D002247:Carbon Isotopes; D002474:Cell-Free System; D002855:Chromatography, Thin Layer; D004586:Electrophoresis; D005557:Formaldehyde / Q000302:isolation & purification; D008298:Maleates / Q000378:metabolism; D008745:Methylation; D009243:NAD; D009539:Nicotinic Acids / Q000378:metabolism*; D010084:Oxidation-Reduction; D010101:Oxygen Consumption; D010269:Paraquat / Q000378:metabolism*; D010782:Photolysis
chemical_list: D002247:Carbon Isotopes; D008298:Maleates; D009539:Nicotinic Acids; D009243:NAD; D002245:Carbon Dioxide; D005557:Formaldehyde; D010269:Paraquat