Transformation of Polycyclic Aromatic Hydrocarbons by Bacteria of the Genus Azospirillum

The study assessed the catabolic potential of 26 bacterial strains of the genus Azospirillum towards polycyclic aromatic compounds (PAHs). It was found that none of the studied strains except A. zeae SR98 was capable of degrading three-ring PAHs present in the medium as the sole source of carbon and energy. However, when succinic acid was added as a co-substrate, the ability to degrade or transform PAHs was observed in four of the studied strains, reaching 41–67% for anthracene, 25–47% for phenanthrene, and 29–54% for fluorene. The detected metabolites resulting from PAH transformation by the studied azospirilla were represented by quinones. A hypothesis is proposed that transformation of PAH substrates by azospirilla may involve a laccase-like enzyme.