FIG. 2.

Utilization of the commercial surfactants NPEO_av20 (a), NPEO_av9 (b), and NPEO_av6 (c) as growth substrates for P. putida. Growth was assessed by optical density measurements (open symbols) of cultures treated with methanol (50% [vol/vol], final concentration) to solubilize metabolites. The initial concentration of surfactant was 1.62 mM, based on UV absorbance, and residual concentrations (filled symbols) were measured as CTAS (620 nm). Different symbol shapes indicate duplicate independent experiments.