Initiation of Anaerobic Degradation of p-Cresol by Formation of 4-Hydroxybenzylsuccinate inDesulfobacterium cetonicum

ABSTRACT The anaerobic bacterium Desulfobacterium cetonicumoxidized p-cresol completely to CO2 with sulfate as the electron acceptor. During growth, 4-hydroxybenzylsuccinate accumulated in the medium. This finding indicated that the methyl group of p-cresol is activated by addition to fumarate, analogous to anaerobic toluene,m-xylene, and m-cresol degradation. In cell extracts, the formation of 4-hydroxybenzylsuccinate fromp-cresol and fumarate was detected at an initial rate of 0.57 nmol min−1 (mg of protein)−1. This activity was specific for extracts of p-cresol-grown cells. 4-Hydroxybenzylsuccinate was degraded further to 4-hydroxybenzoyl-coenzyme A (CoA), most likely via β-oxidation. 4-Hydroxybenzoyl-CoA was reductively dehydroxylated to benzoyl-CoA. There was no evidence of degradation ofp-cresol via methyl group oxidation byp-cresol-methylhydroxylase in this bacterium.

Oxidation of Toluene Over V2O5-Sb2O3/TiO2 Catalysts. Enhancement of Selectivity Towards Benzoic Acid

The effect of reaction parameters, additives and cooxidants on the selectivity of toluene oxidation to benzoic acid in the vapor phase has been studied. The presence of ethanol as cooxidant in the reaction stream does not improve the selectivity of toluene oxidation towards partial oxidation products via methyl group oxidation. However, the presence of carbon dioxide has a positive effect on the selectivity to benzoic acid formation. The catalysts were characterized by temperature programmed reduction.

Intermediary metabolism of Acinetobacter grown on dialkyl ethers

The microbial dissimilation of long-chain dialkyl ethers by Acinetobacter sp. H01-N involved a terminal methyl group oxidation of the dialkyl ether substrates, resulting in the formation of ether oxygen containing fatty acids of corresponding chain length. An internal carbon–carbon scission of the dialkyl ethers resulted in the formation of end-product ether fatty acids and corresponding dicarboxylic acids. Cellular carbon and energy were derived from the subsequent metabolism of the dicarboxylic acids. Dicarboxylic acid oxidation, activation, and identification of cellular dicarboxylic acids indicated dibasic acids as intermediates in the metabolism of dialkyl ethers.Key words: dialkyl ethers, dicarboxylic acids, fatty acids, Acinetobacter.