Estrogenic activity of surfactants and some of their degradation products assessed using a recombinant yeast screen

TLDR

The study developed a yeast‑based estrogen‑inducible assay to determine whether surfactants and their main degradation products exhibit estrogenic activity. A recombinant Saccharomyces cerevisiae strain containing the human estrogen receptor and a lacZ reporter under estrogen‑responsive elements was used, with β‑galactosidase secretion producing a yellow‑to‑red color change upon estrogen binding. None of the parent surfactants were estrogenic, but alkylphenol polyethoxylate metabolites were weakly estrogenic, whereas sulfophenyl carboxylates from linear alkylbenzene sulfonates showed no estrogenic activity.

Abstract

Abstract An estrogen‐inducible screen was developed in yeast ( Saccharomyces cerevisiae ) in order to assess whether surfactants and their major degradation products are estrogenic. The DNA sequence of the human estrogen receptor (hER) was integrated into the yeast genome, which also contained expression plasmids carrying estrogen‐responsive sequences (ERE) controlling the expression of the reporter gene lac‐Z (encoding the enzyme β‐galactosidase). Thus, in the presence of estrogens, β‐galactosidase is synthesized and secreted into the medium, where it causes a color change from yellow to red. This recombinant strain was used to determine whether representatives of major surfactant classes and some of their principal degradation products possess estrogenic activity. The results were compared to the effects of the main natural estrogen 17β‐estradiol. None of the parent surfactants tested possessed estrogenic activity. However, one class of surfactants, the alkylphenol polyethoxylates, degrade to persistent metabolites that were weakly estrogenic. Another group of degradation products, the sulfophenyl carboxylates, which are derived from the biodegradation of linear alkylbenzene sulfonates, do not appear to possess estrogenic activity.