Biodegradation of Sodium Dodecyl Sulphate (SDS) by Serratia marcescens strain DRY6

A bacterium capable of degrading sodium dodecyl sulphate (SDS) is characterized. Previously, the bacterium has been shown to have the capability to reduce molybdenum to molybdenum blue. 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 0.5 to 1 g L-1 while higher concentrations showed partial degradation with no degradation was observed at concentrations higher than 2.5 g L-1. Other detergents were also tested including Tergitol NP9, Tergitol 15S9, Witconol 2301 (methyl oleate), sodium dodecylbenzene sulfonate (SDBS), benzethonium chloride and benzalkonium chloride. However, growth can only be seen on the anionic SDBS. We also showed that the presence of metal ions such as silver, copper, cadmium, chromium, lead and mercury inhibits the ability of the bacterium to degrade SDS by 50%. Growth on SDS could not support molybdenum-reduction in this bacterium. Growth kinetic studies showed that the growth rate could be modelled using Haldane substrate inhibition kinetics with the maximum growth rate, µmax, was 0.13 h-1, while the saturation constant or half velocity constant Ks and inhibition constant Ki, were 0.707 and 11.303 g L-1 SDS, respectively.