During biodegradation, microorganisms can directly metabolize surfactants for energy and nutrients or co-metabolize them with other compounds. Maximum growth of the bacterial consortium on SDS was seen between 30 and 35 °C, while the optimal pH range for bacterial consortium growth was between 6.5 and 7.5. As for the nitrogen source, 2 g/L of ammonium sulfate was optimum in supporting the growth of SDS. The greatest growth rate of the bacterial consortium was recorded at a concentration of between 1 and 1.5 g/L of SDS (p<0.05). At 2–3, g/L of SDS, the bacterial consortium grew more slowly, and at 5 g/L, growth was severely inhibited. Almost complete degradations of SDS were observed in 3, 5 and 6 days at 0.5, 0.75 and 1 g/L SDS, respectively while higher concentrations showed partial degradation with no degradation observed at 2.5 g/L SDS after 6 days of incubation. In this study, the maximum growth rate, or max, Ks, and Ki were 0.517 h-1 (95% confidence interval of C.I. from 0.404 to 0.629), 0.132 (g/L) (95% C.I. from 0.073 to 0.191) and 0.909 (g/L) (95% C.I. from 0.544 to 1.273), respectively. Heavy metals like mercury, copper, and chromium can severely stunt growth if they are present in the environment. It was discovered through research into growth kinetics that Haldane substrate inhibition kinetics may be used to model the growth rate. This bacterial consortium has the right properties for the bioremediation of SDS-polluted environments.

A bacterium capable of degrading sodium dodecyl sulphate (SDS) isolated from a paddy field water is characterized. In this report, we showed that almost complete degradation of SDS was observed in 6 to 10 days when the bacterium was grown on medium supplemented with SDS ranging from 0.75 to 1.75 g/L while higher concentrations showed partial degradation with no degradation was observed at concentrations higher than 2.0 g/L. The SDS-degrading bacterium was partially identified and provisionally named Pseudomonas sp. strain Maninjau1. We also showed that the presence of metal ions such as silver, copper, cadmium, chromium, lead and mercury inhibit the ability of the bacterium to degrade SDS by 50%. Growth kinetic studies show a correlation coefficient value of 0.99 for the Haldane model indicates it fits the curve while a low correlation coefficient value of 0.67 for the Monod model indicates poor fitting. The specific growth rate μ was discovered to rise as the substrate concentration was increased but it reached a peak value followed by a slow decrease indicating substrate inhibition. The calculated qmax or maximum degradation rate was 0.917 h-1 (95% confidence interval or C.I. from 0.664 to 1.171) while the saturation constant Ks or half velocity constant was 0.178 g/L SDS (95% C.I. from 0.089 to 0.266). The inhibition constant Ki was 0.605 g/L SDS (95% C.I. from 0.358 to 0.941). The very high maximum degradation rate obtained in this study indicates that this bacterium can be an efficient agent for bioremediation of SDS especially in soils.