The genes for the initial steps in the degradation of phenanthrene, naphthalene and dibenzothiophene have been cloned and sequenced in many strains. The amino acid sequences of the catabolic
enzymes deduced from their nucleotide sequences are
90% identical to each other. Less homologous groups of
genes coding for enzymes involved in the degradation
of PAHs have been found in Comamonas testosteroni [7]
and Nocardioides sp. [8]. The pathway for the degradation
of naphthalene generally exhibits broad substrate specificity;
for example, Burkholderia cepacia F297 grows on a
wide variety of polycyclic aromatic compounds including
fluorene, (methyl)naphthalene, phenanthrene, anchracene
and dibenzothiophene. An analysis of the intermediates
formed from these growth substrates has indicated that
these compounds are degraded by catalytic reactions very
similar to those for naphthalene degradation [9].