Isolation and characterization of bacteria from activated sludge capable of degrading 17α-ethinylestradiol, a contaminant of high environmental concern

Abstract

The compound 17α-ethinylestradiol (EE2) is a synthetic oestrogen which is classified as a group 1 carcinogen by the World Health Organization. Together with other endocrine disruptor compounds, EE2 has been included in the surface water Watch List by the European Commission, since it causes severe adverse effects in ecosystems. Thus, it became a high priority to find or improve processes such as biodegradation of EE2 to completely remove this drug from the wastewater treatment plants (WWTPs). The present study aimed at the isolation of bacteria capable of degrading EE2 using environmental samples, namely a sludge from the Faro Northwest WWTP. Four isolates with ability to grow in the presence of 50 mg l−1 EE2 were obtained. The analysis of 16SrRNA gene sequences identified the isolated bacteria as Acinetobacter bouvetii, Acinetobacter kookii, Pantoea agglomerans and Shinella zoogloeoides . The results of biodegradation assays showed that Acinetobacter bouvetii , Acinetobacter kookii , Pantoea agglomerans and Shinella zoogloeoides were able to degrade 47±4 %, 55±3 %, 64±4% and 35±4 %, respectively of 13 mg l−1 EE2 after 168 h at 28 °C. To the best of our knowledge, these bacterial isolates were identified as EE2 degraders for the first time. In a preliminary experiment on the identification of metabolic products resulting from EE2 degradation products such as estrone (E1), γ-lactone compounds, 2-pentanedioic acid and 2-butenedioic acid an intermediate metabolite of the TCA cycle, were detected.

Biodegradation of 17α-Ethinylestradiol by Strains of Aeromonas Genus Isolated from Acid Mine Drainage

“…Bacterial isolation was carried out using 1 mL of inoculum from bacterial consortia LN, LACFN and PF, PBDEF. Isolation protocol was performed as described by Palma et al [20,30,34,35].…”

“…Genomic DNA of every single bacterial isolate were obtained utilizing NZY Microbial gDNA Isolation kit (NZYTech, Lisboa, Portugal). The 16S rRNA gene was subjected to amplification, and the resulting PCR products underwent direct sequencing through the Sanger method, as detailed in Palma et al [20,30,34,35], resulting in a partial 16S rRNA gene of about 1484 bp. Taxonomic identification was determined by conducting a Blast search against the Gene Bank database of NCBI and utilising the RDP Classifier.…”

“…In this study, heightened concentrations of EE2, surpassing those typically found in the environment, were employed for various reasons elucidated in previous studies [20,30,34,35].…”

“…The promising results (in which the removal was significant) obtained by quantification in HPLC were further analysed by gas chromatography-mass spectrum (GC-MS). Putative metabolites resulting from the assays involving EE2 were detected and identified using a GC-MS procedure detailed in the study by Palma et al [20]. The GC-MS spectra acquired from experimental samples were interpreted based on a comparison with the National Institute and Technology (NIST) spectra database 2.0.…”

“…According to EE's kinetic reaction rate (k biol ) of 7-9 L/(gSS.day) and its octanol-water partition coefficient (logK ow ) of 2.8-4.2, it could be predicted that the removal of the drug may occur mainly by biodegradation and moderately by adsorption [6,9,20].…”