Uptake, Elimination, and Biotransformation of 17α-Ethinylestradiol by the Freshwater Alga Desmodesmus subspicatus

Abstract

Bioconcentration and transformation of the potent and persistent xeno-estrogen 17α-ethinylestradiol (EE2) by organisms at the basis of the food web have received only little research attention. In this study, uptake, elimination, and biotransformation of radiolabeled EE2 ((14)C-EE2) by the freshwater green alga Desmodesmus subspicatus were investigated. The alga highly incorporated radioactivity following (14)C-EE2 exposure. Up to 68% of the test compound was removed from the medium by D. subspicatus within a rather short time period (72 h C(algae)/C(water): 2200 L/kg wet weight). When the algae were transported to clear medium, a two-stage release pattern was observed with an initially quick elimination phase following slower clearance afterward. Interestingly, D. subspicatus brominated EE2 when bromide was available in the medium, a transformation process demonstrated to occur abiotically but not by algae. The consequence of the presence of more hydrophobic mono- and dibrominated EE2 in the environment remains to be further investigated, as these products were shown to have a lower estrogenic potency but are expected to have a higher bioaccumulation potential and to be more toxic than the mother compound.

Removal of pharmaceuticals and personal care products from wastewater using algae-based technologies: a review

“…In a stream receiving wastewater effluent discharge, triclosan and triclocarban have been found able to bioaccumulate in filamentous algae with estimated bioaccumulation factors up to 2100 and 2700, respectively (Coogan et al 2007). Maes et al (2014) studied the removal of EE2 by Desmodesmus subspicatus and found EE2 can be taken up and biotransformed in algal cells and the ratio of EE2 between algae and water reached a maximum value of 2700 L kg -1 (Dry weight) after 24 h.…”

The Use of Algae and Fungi for Removal of Pharmaceuticals by Bioremediation and Biosorption Processes: A Review

“…Such as for fungi, pollutant degradation by algae seems to involve intracellular and extracellular enzymatic systems (Figure 3). Intracellular degradation of pharmaceuticals involves a phase I enzyme (cytochrome P450) [163,[168][169][170][171][172][173] and a phase II enzyme (e.g., glutathione-S-transferases) [171]. Extracellular degradation of pharmaceuticals involves the excretion of various extracellular polymeric substances, such as polysaccharides, protein, enzymes, substituents (polysaccharide-link methyl and acetyl groups), and lipids to their surrounding environment.…”

“…Some algae strains found in the literature [64,133,148,164,166,[168][169][170][176][177][178][179][180][182][183][184][185][186][187][188][189][190][191][192][193][194] proved to be effective in pharmaceutical removal (Table 1). Laboratory-scale batch assays [190] Biodegradation Laboratory-scale batch assays [191] Salicylic acid or paracetamol Pharmaceutical industry wastewater Algae…”

Using agro-industrial wastes for the cultivation of microalgae and duckweeds: Contamination risks and biomass safety concerns

“…During microalgae/duckweed cultivation estrogens are converted from one form into another; E1, E2 and EE2 can be interconverted rapidly, during a few hours of cultivation, while estrone (E1) is transformed into estriol and after an extended period (> 7 days) is further degraded into unknown lipophilic products (Lai et al, 2002;Shi et al, 2010;Zhang et al, 2014c). Among the removal mechanisms, it was shown that photodegradation and direct oxidation accounted for a small fraction of the total estrogen removal (Maes et al, 2014;Shi et al, 2010;Zhang et al, 2014c). On the other hand, even as the final removal of total estrogen can reach over than 85%, it was shown that the estrogenic activity of the medium was not reduced suggesting that the degradation products displayed the same or higher estrogenic activity compared to the parent compounds (Zhang et al, 2014c).…”

“…The degree of intracellular concentration of estrogen has not yet been extensively investigated; however, it was shown that the microalga Desmodesmus subspicatus incorporated around 23% EE2 from its surrounding medium after 24 h, with no further uptake. After re-incubation of contaminated cells in clean medium a portion of EE2 was desorbed, but 30% of the initially incorporated estrogen remained in the microalgal biomass (Maes et al, 2014), suggesting, at least partially, a gradient driven adsorption onto cell surfaces.…”