Bacterial oxidation of chemical carcinogens: formation of polycyclic aromatic acids from benz[a]anthracene

A Beijerinckia strain designated strain B1 was shown to oxidize benz[a]anthracene after induction with biphenyl, m-xylene, and salicylate. Biotransformation experiments showed that after 14 h a maximum of 56% of the benz[a]anthracene was converted to an isomeric mixture of three o-hydroxypolyaromatic acids. Nuclear magnetic resonance and mass spectral analyses led to the identification of the major metabolite as 1-hydroxy-2-anthranoic acid. Two minor metabolites were also isolated and identified as 2-hydroxy-3-phenanthroic acid and 3-hydroxy-2-phenanthroic acid. Mineralization experiments with [12-14C]benz[a]anthracene led to the formation of 14CO2. These results show that the hydroxy acids can be further oxidized and that at least two rings of the benz[a]anthracene molecule can be degraded.