Metabolism-independent chemotaxis of Pseudomonas sp. strain WBC-3 toward aromatic compounds

Pseudomonas sp. strain WBC-3 utilized methyl parathion or para-nitrophenol (PNP) as the sole source of carbon, nitrogen, and energy, and methyl parathion hydrolase had been previously characterized. Its chemotactic behaviors to aromatics were investigated. The results indicated that strain WBC-3 was attracted to multiple aromatic compounds, including metabolizable or transformable substrates PNP, 4-nitrocatechol, and hydroquinone. Disruption of PNP catabolic genes had no effect on its chemotactic behaviors with the same substrates, indicating that the chemotactic response in this strain was metabolism-independent. Furthermore, it was shown that strain WBC-3 had a constitutive β-ketoadipate chemotaxis system that responded to a broad range of aromatic compounds, which was different from the inducible β-ketoadipate chemotaxis described in other Pseudomonas strains.