Growth curves and SDS degradation by Y . ruckeri parental and yraS mutant strains. Cultures were incubated in NB containing 0.25% (w/v) SDS at 28°C and 250 rpm and, at different times, samples were withdrawn and growth determined by plate counting. Simultaneously, the presence of SDS in the culture supernatant was quantified by the Stains-all method . Continuous line and dotted line represents the growth and SDS degradation of parental (■) and yraS− (○) strains. Data represent the mean ± standard deviation of three independent experiments. Growth was similar for the two strains, but SDS was completely degraded by the parental strain after 24 h of incubation, whereas no degradation at all occurred by the yraS mutant strain.