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Full-Text Articles in Life Sciences

Applied And Mechanistic Studies Of Microbial 17beta-Estradiol Degradation, Zhongtian Li Nov 2012

Applied And Mechanistic Studies Of Microbial 17beta-Estradiol Degradation, Zhongtian Li

Z Li

The presence of natural estrogens, a class of endocrine disrupting compounds, in water has caused increasing concerns over their adverse impacts on the health of aquatic eco-systems and human beings. In this study, adsorption characteristics of two natural estrogens, 17β-estradiol (E2) and estrone (E1), on granular activated carbon (GAC) were investigated in isotherm tests and in a GAC column. The GAC column was then converted to a biologically active carbon (BAC) column and the removal efficiency of E2 and its primary biodegradation intermediate E1 were monitored. During BAC operation, the impacts of various reactor operation parameters, such as the carbon …


Proteomic Analysis Of 17Β-Estradiol Degradation By Stenotrophomonas Maltophilia, Zhongtian Li May 2012

Proteomic Analysis Of 17Β-Estradiol Degradation By Stenotrophomonas Maltophilia, Zhongtian Li

Z Li

Microbial degradation plays a critical role in determining the environmental fate of steroid hormones, such as 17β-estradiol (E2). The molecular mechanisms governing the microbial transformation of E2 and its primary degradation intermediate, estrone (E1), are largely unknown. The objective of this study was to identify metabolism pathways that might be involved in microbial estrogen degradation. To achieve the objective, Stenotrophomonas maltophilia strain ZL1 was used as a model estrogen degrading bacterium and its protein expression level during E2/E1 degradation was studied using quantitative proteomics. During an E2 degradation experiment, strain ZL1 first converted E2 to E1 stoichiometrically. At 16 h …


Removing 17Β-Estradiol From Drinking Water In A Biologically Active Carbon (Bac) Reactor Modified From A Granular Activated Carbon (Gac) Reactor, Zhongtian Li Mar 2012

Removing 17Β-Estradiol From Drinking Water In A Biologically Active Carbon (Bac) Reactor Modified From A Granular Activated Carbon (Gac) Reactor, Zhongtian Li

Z Li

Estrogenic compounds in drinking water sources pose potential threats to human health. Treatment technologies are needed to effectively remove these compounds for the production of safe drinking water. In this study, GAC adsorption was first tested for its ability to remove a model estrogenic compound, 17β-estradiol (E2). Although GAC showed a relatively high adsorption capacity for E2 in isotherm experiments, it appeared to have a long mass transfer zone in a GAC column reactor, causing an early leakage of E2 in the effluent. With an influent E2 concentration of 20 μg/L, the GAC reactor was able to bring down effluent …