Two denitrifying bacteria were isolated using sodium dodecyl sulfate (SDS) as substrate. Strains SN1 and SN2 were isolated from an activated sludge reactor of a wastewater treatment plant (WWTP) with Anaerobic-Anoxic-Oxic (A2/O) steps. Based on 16S rRNA gene analysis strain SN1 is 99% similar to Pseudomonas stutzeri (CCUG 11256T), while strain SN2 is 99% similar to Pseudomonas nitroreducens (DSM 14399T). The two novel strains are able to grow with a variety of organic compounds, including intermediates of SDS degradation. Alkylsulfatase activity was induced by SDS in strain SN1 and was enhanced by SDS in strain SN2. The type strain P.stutzeri (CCUG 11256T) is not able to grow with SDS. However, P.nitroreducens (DSM 14399T) is able to degrade and grow with SDS and nitrate or oxygen as electron acceptors, adding new information to the physiological abilities of this type strain.