Evolution of catabolic pathways and metabolic versatility in Pseudomonas stutzeri OX1

Pseudomonas stutzeri OX1 is able to degrade toluene and ortho-xylene via th e direct oxygenation of the aromatic ring. The genetic studies carried out suggest that the genes coding for the monooxygenase involved in the early s teps of this catabolic route have been acquired by gene transfer. P. stutze ri OX1 is also potentially able to utilize meta- and para-xylene as growth substrates. These two isomers are metabolized through a different pathway ( TOL pathway). Both catabolic routes can be activated or inactivated by mean s of genomic rearrangements. The relevance of such recombination mechanisms in the evolution and the adaptability of P. stutzeri is discussed.