potassium-bicarbonate and gamma-resorcylic-acid

We found a bacterium, Pandoraea sp. 12B-2, of which whole cells catalyzed not only the decarboxylation of 2,6-dihydroxybenzoate but also the regioselective carboxylation of 1,3-dihydroxybenzene to 2,6-dihydroxybenzoate. The whole cells of Pandoraea sp. 12B-2 also catalyzed the regioselective carboxylation of phenol and 1,2-dihydroxybenzene to 4-hydroxybenzoate and 2,3-dihydroxybenzoate, respectively. The molar conversion ratio of the carboxylation reaction depended on the concentration of KHCO(3) in the reaction mixture. Only 5 or 48 % of 1,3-dihydroxybenzene added was converted into 2,6-dihydroxybenzoate in the presence of 0.1 M or 3 M KHCO(3), respectively. The addition of acetone to the reaction mixture increased the initial rate of the carboxylation reaction, but the final molar conversion yield reached almost the same value. When the efficient production of 2,6-dihydroxybenzoate was optimized using the whole cells of Pandoraea sp. 12B-2, the productivity of 2,6-dihydroxybenzoate topped out at 1.43 M, which was the highest value so far reported. No formation of any other products was observed after the carboxylation reaction.

Topics: Acetone; Bicarbonates; Burkholderiaceae; Carboxy-Lyases; Catechols; Hydroxybenzoates; Parabens; Phenol; Potassium Compounds

A nonoxidative decarboxylase, 2,6-dihydroxybenzoate decarboxylase, was found in Agrobacterium tumefaciens IAM12048. The enzyme activity was induced specifically by 2,6-dihydroxybenzoate. The purified enzyme was a homotetramer of identical 38 kDa subunits. The purified decarboxylase catalyzed the nonoxidative decarboxylation of 2,6-dihydroxybenzoate and 2,3-dihydroxybenzoate without requiring any cofactors. In the presence of KHCO(3), the enzyme also catalyzed the regioselective carboxylation of 1,3-dihydroxybenzene into 2,6-dihydroxybenzoate at a molar conversion ratio of 30%.

Topics: Agrobacterium tumefaciens; Bicarbonates; Carboxy-Lyases; Coenzymes; Decarboxylation; Enzyme Stability; Hydrogen-Ion Concentration; Hydroxybenzoates; Kinetics; Molecular Weight; Potassium Compounds; Protein Subunits; Resorcinols; Stereoisomerism; Substrate Specificity