ISSN:
1432-072X
Keywords:
Aromatic compounds
;
2-Aminobenzoic acid
;
Benzoic acid
;
Anaerobic degradation
;
Pseudomonas sp
;
Anthranilic acid
;
Denitrification
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract The growth of a denitrifying Pseudomonas strain on benzoic acid and 2-aminobenzoic acid (anthranilic acid) has been studied. The organism grew aerobically on benzoate, 2-aminobenzoate, and gentisate, but not on catechol or protocatechuic acid. These and other findings suggest that aerobic degradation of benzoic acid was via gentisic acid. Under completely anaerobic conditions in the presence of nitrate, benzoate and 2-aminobenzoate (5 mM each) were oxidized to CO2 with the concurrent reduction of NO 3 - to NO 2 - . Only after complete NO 3 - consumption was NO 2 - reduced to N2. Cells contained a NADP-specific 2-oxoglutaate dehydrogenase, in contrast to a NAD-specific pyruvate dehydrogenase. During anaerobic metabolism of [carboxyl-14C]benzoic acid, 16% of the label of metabolized benzoic acid was incorporated into cell material; this excludes intermediary decarboxylation during anaerobic metabolism. Extracts catalysed the activation of benzoic acid and a variety of its derivatives to the respective aryl-coenzyme A thioesters, ATP being cleaved to AMP and PPi; two synthetase activites were present. Extracts from 2-aminobenzoate-grown cells catalyzed a NADH-dependent reduction of 2-aminobenzoyl-CoA (100 nmol·min-1·mg-1 cell protein) to an unidentified CoA thioester, with a stoichiometric release of NH3 and a stoichiometry of ≈ 3 mol NADH oxidized per mol 2-aminobenzyol-CoA reduced when tested under aerobic conditions. The 2-aminobenzoyl-CoA reductase activity was lacking in anaerobic benzoate-grown cells and in aerobic cells. This is taken as evidence that 2-aminobenzoyl-CoA reductase is a key enzyme in a novel reductive pathway of anaerobic 2-aminobenzoic acid metabolism.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00423138
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