Removal and Biodegradation of 17β-Estradiol and Diethylstilbestrol by the Freshwater Microalgae Raphidocelis subcapitata

Abstract

Natural steroidal and synthetic non-steroidal estrogens such as 17β-estradiol (E2) and diethylstilbestrol (DES) have been found in natural water, which can potentially endanger public health and aquatic ecosystems. The removal and biodegradation of E2 and DES by Raphidocelis subcapitata were studied in bacteria-free cultures exposed to single and mixture treatments at different concentrations for 96 h. The results showed that R. subcapitata exhibited a rapid and strong ability to remove E2 and DES in both single and mixture treatments by biodegradation. At the end of 96 h, the removal percentage of single E2 and DES achieved 82.0%, 80.4%, 74.6% and 89.9%, 73.4%, 54.1% in 0.1, 0.5, and 1.5 mg·L−1, respectively. With the exception of the 0.1 mg·L−1 treatment at 96 h, the removal capacity of E2 was more efficient than that of DES by R. subcapitata. Furthermore, the removal percentage of mixture E2 and DES achieved 88.5%, 82.9%, 84.3% and 87.2%, 71.8%, 51.1% in 0.1, 0.5, and 1.5 mg·L−1, respectively. The removal percentage of mixed E2 was significantly higher than that of the single E2. The presence of DES could accelerate the removal of E2 from the mixture treatments in equal concentrations. In addition, the removal was mainly attributed to the biodegradation or biotransformation process by the microalgae cells rather than simple sorption and accumulation in the cells. The microalgae R. subcapitata demonstrated a high capability for the removal of the E2 and DES indicating future prospects for its application.

Mycoremediation of 17 β‐Estradiol Using Trichoderma citrinoviride Strain AJAC3 along with Enzyme Studies

“…Not much work has been conducted to determine the MIC of E2 against fungi. In a recent study, microalgae, Raphidocelis subcapitata was reported to withstand maximum concentration 3.2 mg L −1 of E2 whereas strain AJAC3, in this study, showed much higher rate of tolerance against the contaminant [25].…”

Suitability of Immobilized Systems for Microbiological Degradation of Endocrine Disrupting Compounds

“…The latter is considered to be the strongest among the endocrine factors in the environment [ 10 ]. Synthetic estrogens have been divided into steroidal, such as 17α-ethynylestradiol and 3-methyl ether of ethynylestradiol, used as ingredients of birth control pills, and nonsteroidal estrogens such as diethylstilbestrol used to prevent miscarriages [ 3 , 7 , 11 ]. Human use of the latter was banned in 1972 due to its negative effects, however, it is still used in China as a growth promotor for terrestrial livestock or fish [ 11 ].…”

“…This biological activity can lead to low levels of estrogen in the environment causing endocrine disorders in the wildlife population. Negative effects on development, sex differentiation, reproduction of different animal species and production of vitellogenin have been documented [ 3 , 4 , 7 , 11 , 12 ]. Intersexual disorders in fish in Europe, and a negative impact on the sexual behaviour of frogs in suburban areas in the United States have been observed [ 12 ].…”

“…This observation is all the more important because of the environment where we usually deal with mixtures of hormones. Moreover, estrogens can accumulate in the food chain and the effects may appear in the next generation, threatening the health of the human population [ 4 , 11 , 24 ]. Also, the World Health Organization classified estrogens as group 1 carcinogens and some of their catechol metabolites such as 4-hydroxyestrone are also carcinogens [ 12 , 25 ].…”

“…In developed countries, where the problem of endocrine substances is the greatest, sewage treatment plants play a key role in their removal. Organisms involved in the removal of estrogens from the environment include bacteria, as well as fungi and microalgae ( Figure 1 ) [ 11 ].…”