Desulfonation of Linear Alkylbenzenesulfonate Surfactants and Related Compounds by Bacteria

Abstract

Pseudomonas putida S-313 (= DSM 6884) grew in sulfate-free medium when the sole sulfur source supplied was one of several arylsulfonates involved in the synthesis, application, or biodegradation of linear alkylbenzenesulfonate (LAS) surfactants. 2-(4-Sulfophenyl)butyric acid, 4-n-butyl-1-methyl-6-sulfotetralin, and 4-toluenesulfonic acid were each completely utilized during growth, as were the model LAS 1-(4-sulfophenyl) octane and the arylsulfonate dyestuff Orange II. The product in each case was the corresponding phenol, which was identified by gas chromatography-mass spectrometry or 'H nuclear magnetic resonance. Stoichiometric conversion of 4-toluenesulfonic acid to 4-cresol was observed. The molar growth yields observed were 2.4 to 2.8 kg of protein per mol of S, which were comparable to the yield for sulfate. Commercial LAS disappeared from growth medium inoculated with strain S-313, but negligible growth occurred; digestion of cells in alkali led to recovery of the LAS mixture, which seemingly sorbed to the cells. However, mixed culture L6 was readily obtained from batch enrichment cultures containing commercial LAS as a sole sulfur source and an inoculum from domestic sewage. Culture L6 desulfonated components of the LAS surfactant to the corresponding phenols, which were identified by gas chromatography-mass spectrometry. Compounds with shorter alkyl chains were desulfonated preferentially, as were the centrally substituted isomers. In the presence of200 ,uM sulfate, culture L6 grew well and LAS disappeared, although this was due purely to sorption, as shown by digestion of the cells in alkali. Thus, under sulfate-limited conditions, LAS can be desulfonated directly.

Anaerobic Degradation of Linear Alkylbenzene Sulfonate

“…Quantification was conducted on a HP1100 high-pressure liquid chromatography system (Hewlett-Packard, Waldbronn, Germany) equipped with a C18 column (250 by 4.6 mm; particle size 5 m) from Agilent (Naerum, Denmark) using ultraviolet detection ( ϭ 225 nm). The LAS homologs were separated using a mobile phase of 9.2 g/L of NaClO 4 in Milli-Q water (Millipore, Bedford, MA, USA) with an acetonitrile gradient (0-100% v/v) as described by Kertesz et al [14].…”

Microbial metabolism of sulfurand phosphorus-containing xenobiotics

“…The enzyme concerned has not yet been purified. Under the same conditions, P. putida S-313 can also desulfonate compounds related to LAS: psulfophenylbutyrate, p-octanesulfonate and dialkyltetralinsulfonate are each converted to the corresponding phenol [93]. No degradation of the sulfonate occurs in the presence of sulfate or cysteine, suggesting that the desulfonative system is subject to regulation by sulfur levels.…”

Desulfonation of biotransformation products from commercial linear alkylbenzenesulfonates

“…We have no data on the products formed from the components of ROC, but we expect that the corresponding phenol is formed from the sulfonate [14,20,21]. It is generally held [4] that if a molecule with a sulfonate substituent (as the second substituent on the aromatic ring) is poorly degraded, the corresponding phenol is very much more likely to be degradable.…”

“…3). Since its discovery [14,19], the phenomenon of assimilation of sulfur from xenobiotic arylsulfonates has been shown to be widespread in bacteria, where different bacteria have different substrate ranges [20][21][22][23]. We thus expect that, if desulfonation by strain S-313 is incomplete, desulfonation in mixed culture (e.g., soil) could be completed by other microorganisms.…”