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W C Evans

Publications and source records attributed to W C Evans.

At least 37 records · Page 2Linked to original sources
PubMed1975

The metabolism of benzoate by Moraxella species through anaerobic nitrate respiration. Evidence for a reductive pathway.

Moraxella sp. isolated from soil grows anaerobically on benzoate by nitrate respiration; nitrate or nitrite are obligatory electron acceptors, being reduced to molecular N2 during the catabolism of the substrate. This bacterium also grows aerobically on benzoate. 2. Aerobically, benzoate is metabolized by ortho cleavage of catechol followed by the beta-oxoadipate pathway. 3. Cells of Moraxella grown anaerobically on benzoate are devoid of ortho and meta cleavage enzymes; cyclohexanecarboxylate and 2-hydroxycyclohexanecarboxylate were detected in the anaerobic culture fluid. 4. [ring-U-14C]Benzoate, incubated anaerobically with cells in nitrate-phosphate buffer, gave rise to labelled 2-hydroxycyclohexanecarboxylate and adipate. When [carboxy-14C]benzoate was used, 2-hydroxycyclohexanecarboxylate was radioactive but the adipate was not labelled. A decarboxylation reaction intervenes at some stage between these two metabolites. 5. The anaerobic metabolism of benzoate by Moraxella sp. through nitrate respiration takes place by the reductive pathway (Dutton & Evans, 1969). Hydrogenation of the aromatic ring probably occurs via cyclohexa-2,5-dienecarboxylate and cyclohex-1-enecarboxylate to give cyclohexanecarboxylate. The biochemistry of this reductive process remains unclear. 6. CoA thiol esterification of cyclohexanecarboxylate followed by beta-oxidation via the unsaturated and hydroxy esters, would afford 2-oxocyclohexanecarboxylate. Subsequent events in the Moraxella culture differ from those occurring with Rhodopseudomonas palustris; decarboxylation precedes hydrolytic cleavage of the alicyclic ring to produce adipate in the former, whereas in the latter the keto ester undergoes direct hydrolytic fission to pimelate.

Anaerobiosis↗
PubMed1975

The aerobic metabolism of cyclohexanecarboxylic acid by Acinetobacter anitratum.

1. The aerobic metabolism of cyclohexanecarboxylic acid by a bacterium isolated from garden soil (Acinetobacter anitratum) was investigated. 2. Evidence for the formation of cyclohex-1-ene-1-carboxylate, 2-hydroxycyclohexanecarboxylate and pimelate when either cell suspensions or cell-free extracts were incubated in the presence of cyclohexanecarboxylic acid is presented. 3. Crude cell-free extracts required ATP, CoA, FAD and Mg2+ as cofactors for the production of pimelate from cyclohexanecarboxylic acid, suggesting the existence of an activating reaction with formation of CoA esters, in this system.

Acinetobacter↗
PubMed1972

The bacterial oxidation of picolinamide, a photolytic product of Diquat.

The pathway of oxidation of picolinamide (pyridine-2-carboxamide) by a Gram-negative rod has been elucidated. Under conditions of high pH, restricted aeration and high substrate concentration, whole cells released 2,5-dihydroxypyridine into culture supernatants. Sodium arsenite at 5mm caused whole cells to accumulate 6-hydroxypicolinate, and, at 1mm, pyruvate, in culture media. Whole cells oxidized picolinamide, picolinate, 6-hydroxypicolinate, maleamate and maleate without lag. Cell-free extracts converted picolinamide into picolinate, and hydroxylated picolinate to 6-hydroxypicolinate. The hydroxylase was particulate, but could be solubilized by ultrasonic treatment; it required NAD(+) for activity, and did not require molecular oxygen. 2,5-Dihydroxypyridine was converted into maleamate and formate by an oxygenase requiring GSH and Fe(2+). Maleamate was deamidated to maleate, and maleate isomerized to fumarate, by unsupplemented extracts.

Amides↗
PubMed1972

The bacterial oxidation of N-methylisonicotinate, a photolytic product of paraquat.

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(+).

Bacteria↗
PubMed1972

The bacterial degradation of flavonoids. Oxidative fission of the A-ring of dihydrogossypetin by a Pseudomonas sp.

Cell-free extracts prepared from a Pseudomonas sp., grown on (+)-catechin, oxidized dihydrogossypetin (3',4',5,7,8-pentahydroxyflavanonol) by cleaving the A-ring to form oxaloacetic acid from C-5, C-6, C-7 and C-8 together with 5-(3,4-dihydroxyphenyl)-4-hydroxy-3-oxovalero-delta-lactone. The structure of this lactone was confirmed by synthesis of related phenylvalerolactones.

Carbon Isotopes↗