Microbial Production of Pyrogallol through Decarboxylation of Gallic Acid

Abstract

Cultural conditions for the microbial production from gallic acid of pyrogallol were investigated with Citrobacter sp. The maximal formation of pyrogallol was observed when the bacterium was cultured at 28°C for 48 hr in a medium containing 2.0% gallic acid, 0.5% maltose, 0.2% (NH₄)₂HP0₄, 0.1% KH₂P0₄, 0.05% KCl, 0.05% MgS0₄-7H₂0 and 0.05% yeast extract (pH 6.0). Under these conditions, 7.2 g of pyrogallol was formed from 20 g of gallic acid added to one liter of the medium. Larger amounts of pyrogallol could be produced when gallic acid was further added to the broth after 16 ~ 24 hr cultivation. The reaction was performed at pH 4.5 under anaerobic conditions using 1 mm l-ascorbic acid and N₂ gas. Seventy-five grams of gallic acid added to one liter of the broth was transformed to 54.1 g of pyrogallol under these conditions, with a yield of 97.4%.