Novel Alkylsulfatases Required for Biodegradation of the Branched Primary Alkyl Sulfate Surfactant 2-Butyloctyl Sulfate

Abstract

Recent reports show that contrary to common perception, branched alkyl sulfate surfactants are readily biodegradable in standard biodegradability tests. We report here the isolation of bacteria capable of biodegrading 2-butyloctyl sulfate and the identification of novel enzymes that initiate the process. Enrichment culturing from activated sewage sludge yielded several strains capable of growth on 2-butyloctyl sulfate. Of these, two were selected for further study and identified as members of the genus Pseudomonas. Strain AE-A was able to utilize either sodium dodecyl sulfate (SDS) or 2-butyloctyl sulfate as a carbon and energy source for growth, but strain AE-D utilized only the latter. Depending on growth conditions, strain AE-A produced up to three alkylsulfatases, as shown by polyacrylamide gel electrophoresis zymography. Growth on either SDS or 2-butyloctyl sulfate or in nutrient broth produced an apparently constitutive, nonspecific primary alkylsulfatase, AP1, weakly active on SDS and on 2-butyloctyl sulfate. Growth on 2-butyloctyl sulfate produced a second enzyme, AP2, active on 2-butyloctyl sulfate but not on SDS, and growth on SDS produced a third enzyme, AP3, active on SDS but not on 2-butyloctyl sulfate. In contrast, strain AE-D, when grown on 2-butyloctyl sulfate (no growth on SDS), produced a single enzyme, DP1, active on 2-butyloctyl sulfate but not on SDS. DP1 was not produced in broth cultures. DP1 was induced when residual 2-butyloctyl sulfate was present in the growth medium, but the enzyme disappeared when the substrate was exhausted. Gas chromatographic analysis of products of incubating 2-butyloctyl sulfate with DP1 in gels revealed the formation of 2-butyloctanol, showing the enzyme to be a true sulfatase. In contrast, Pseudomonas sp. strain C12B, well known for its ability to degrade linear SDS, was unable to grow on 2-butyloctyl sulfate, and its alkylsulfatases responsible for initiating the degradation of SDS by releasing the parent alcohol exhibited no hydrolytic activity on 2-butyloctyl sulfate. DP1 and the analogous AP2 are thus new alkylsulfatase enzymes with novel specificity toward 2-butyloctyl sulfate.Synthetic surfactants are components of a variety of household and industrial detergent formulations. Other industrial applications include paints, textiles and fabrics, oil-spill dispersants, concrete, paper, lubricants, and many others (14,15,26). In 1990, world production of synthetic surfactants was 7 megatonnes (Mt) per annum, of which 5.3 Mt came from the United States, the European Union, and Japan (12). Of this part, 1.74 Mt per annum was anionic surfactant, a significant quantity which reflects the high demand for this type of surfactant. The anionic surfactant group embraces a range of compounds distinguished on the basis of chemical structure and includes primary alkyl sulfates, such as sodium dodecyl sulfate (SDS), and linear secondary alkyl sulfates, such as dodecyl 2-sulfate. Synthetic primary alkyl sulfates are based on feedstocks derived from long-chain olefins by us...

Effect of temperature and organic nutrients on the biodegradation of linear alkylbenzene sulfonate (LAS) during the composting of anaerobically digested sludge from a wastewater treatment plant

“…In the enrichment tests, a mineral basal medium was used, comprising inorganic compounds (K 2 HPO 4 , 3.5 g/l; KH 2 PO 4 , 1.5 g/l; NH 4 Cl, 0.5 g/l; NaCl, 0.5 g/l; Na 2 SO 4 , 0.14 g/l; MgCl 2 AE 6H 2 O, 0.15 g/l), to which an oligoelement solution was added to a concentration of 0.1% (v/v) (prepared with FeCl 3 AE 6H 2 O, 0.24 g/l; CoCl 2 AE 6H 2 O, 0.04 g/l; CuSO 4 AE 5H 2 O, 0.06 g/l; MnCl 2 AE 4H 2 O, 0.03 g/l; ZnSO 4 AE 7H 2 O, 0.31 g/l; Na 2 MoO 4 AE 2H 2 O, 0.03 g/l) according to Ellis et al (2002).…”

Cell aggregation of Pseudomonas aeruginosa strain PAO1 as an energy-dependent stress response during growth with sodium dodecyl sulfate

“…Sulfate ester detergents like sodium dodecyl sulfate (SDS) are considered as readily biodegradable (Scott and Jones 2000). Several publications have described SDS degradation by pure cultures of Pseudomonas strains (Payne and Feisal 1963;Stavskaia et al 1989;Marchesi et al 1994;Ellis et al 2002). Degradation is started by an alkyl sulfatase which hydrolyses SDS to sulfate and 1-dodecanol.…”

Metabolism Dependent Chemotaxis of Pseudomonas aeruginosa N1 Towards Anionic Detergent Sodium Dodecyl Sulfate

“…Cell pellets were washed with 10 mL 10 mM TrisHCl and was resuspended in 2.5 mL 10 mM Tris-HCl (pH 7.5) (1/100 the original volume). The enzyme extracts were prepared following the method of Ellis et al [21].…”

“…Alkyl sulfatase assay and zymography of alkyl sulfatase were carried out following the method of Ellis et al [21]. Alkyl sulfatase activity in the crude enzyme extracts was performed in triplicate and results were depicted as mean ± standard deviation.…”