Anaerobic degradation of pimelate by newly isolated denitrifying bacteria

Abstract

A C, dicarboxylic (pimelic) acid derivative is postulated as an intermediate in anaerobic degradation of benzoate. Four strains of Gram-negative, nitratereducing bacteria capable of growth with both pimelate and benzoate as sole carbon and energy source were isolated. The metabolism of strain LP-1, which was enriched from activated sludge with pimelate as substrate, was studied in detail. This strain grew only with oxygen or with oxidized nitrogen compounds as electron acceptor. In the presence of nitrate, a wide range of substrates excluding C, compounds was degraded. The new isolate was catalase-and oxidase-positive, and had one single polar f lagellum. Strain LP-1 was tentatively classified within the family Pseudomonadaceae. The catabolism of pimelate and benzoate was studied in cell-free extracts of strain LP-1. Both acids were activated with coenzyme A in a Mg2+-and ATP-dependent reaction. The corresponding acyl-CoA synthetases were specifically induced by the respective growth substrate. Pimelate was also activated by CoA transfer from succinyl-CoA. Pimelyl-CoA was oxidized by cell-free extracts in the presence of potassium ferricyanide. Degradation to glutaryl-CoA and acetyl-CoA proceeded by a sequence of P-oxidation-like reactions. Glutaryl-CoA dehydrogenase and glutaconyl-CoA decarboxylase activities were expressed in cells grown with pimelate or benzoate, indicating the specific involvement of these enzyme activities in anaerobic degradation of these two acids. Enzyme activities responsible for further degradation of the resulting crotonyl-CoA to acetylCoA via classical /?-oxidation were also detected.

Metabolism of Benzoate, Cyclohex-1-ene Carboxylate, and Cyclohexane Carboxylate by “ Syntrophus aciditrophicus ” Strain SB in Syntrophic Association with H 2 -Using Microorganisms

“…The pimelyl-CoA dehydrogenase activity, which was demonstrated for the first time in a benzoate-grown anaerobic microorganism, was not detected in a nitrate-reducing isolate when it was grown with benzoate (16), probably because benzoate degradation in the isolate proceeds via transformation of cyclohex-1,5-diene carboxyl-CoA to 3-hydroxypimelate without the formation of pimelyl-CoA. The dehydrogenase activity was detected, however, when the same isolate was grown on pimelate (16). It could also be argued that the observed cyclohex-1-ene carboxyl-CoA hydratase activity is due to the action of an enoyl-CoA hydratase, which acts primarily on short-chain unsaturated fatty acids (28).…”

Anaerobic Catabolism of Aromatic Compounds: a Genetic and Genomic View

“…A glutaryl-CoA dehydrogenase was significantly produced in crude extracts of bacteria growing anaerobically in aromatic compounds (and cyclohexane carboxylate), which suggests that glutaryl-CoA was indeed an intermediate formed during the catabolism of these compounds via the pimelyl-CoA/3-hydroxypimelyl-CoA ␤-oxidation pathway (28,106,118,140,141,153,328). Recently, the gcdH gene, encoding the bifunctional glutaryl-CoA dehydrogenase enzyme, has been identified and characterized for Azoarcus sp.…”

“…The further degradation of the aliphatic C 7 -dicarboxyl-CoA derivative generates three acetyl-CoAs and CO 2 ( Fig. 3) (118,140). Usually, bacteria contain many genes that might participate in the metabolism of the dicarboxyl-CoA intermediates formed during the anaerobic metabolism of aromatic (and alicyclic) acids as well as in the catabolism of dicarboxylic acids.…”

“…3), have been detected in several bacteria (10,106,107,118,328), and genes predicted to encode these enzymes have been proposed after the in silico analysis of the genomes of some anaerobic biodegraders (140,290).…”

New halo- and thermotolerant fermenting bacteria producing surface-active compounds

“…Succinate and sugars were quantified by HPLC with an Interaction ORH-801 organic acids column packed with a cation-exchange polymer (Interaction Chemicals, Mountain View, USA) and refractive-index detection (Gallus and Schink 1994). Production of surface-active substances was first checked half-quantitatively following the unmixing process of The original publication is available at www.springerlink.com First publ.…”