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Biodegradation of ibuprofen and fluoxetine by bacterial strains isolated from environmental samples and identification of candidate catabolic genes

Publication . Vargas Villagómez, Ayleen Dayana; Costa, Maria Clara

Pharmaceuticals are commonly found in surface waters due to high global demand. Conventional wastewater treatment plants don’t remove them completely being a major source of these compounds, which pose a risk to the environment and human health despite their low concentrations. The objective of the present investigation was to isolate bacteria from environmental and wastewater samples from the Algarve area potentially exposed to recalcitrant contaminants (aromatic compounds), capable of degrading pharmaceuticals. Ibuprofen (IBU) and fluoxetine (FLX), two of the most common drugs found in effluents worldwide, were the targets. Twenty bacterial strains were isolated using enrichment cultures. However, only three strains (TIBU2.1, LOI1.1 and LOI1.2) showed the ability to degrade IBU, and two (LOFLX1.1 and LOFLX1.3) FLX. The drug concentration was monitored by HPLC, as well as the presence of IBU metabolites eventually formed during biodegradation. In addition, two bacterial strains (Mycolicibacterium aubagnense HPB1.1 and Micrococcus yunnanensis TJTP4), previously isolated for other pharmaceuticals, were investigated in this work. Klebsiella pneumoniae TIBU2.1 and M. yunnanensis TJTP4 exhibited complete degradation of IBU after 15 and 14 days, respectively, while M. aubagnense HPB1.1 was also able to degrade 60.2% ± 0.4 of IBU after 21 days. Additionally, the complete genomes of these three bacterial strains were sequenced to conduct a preliminary analysis of candidate genes involved in the degradation pathway of IBU. Catabolic enzymes reported in databases and literature for IBU biodegradation were used to search for similar proteins translated by the obtained genome sequences. These in silico analyses on the bacterial genomes showed similarities with most of the reported proteins. This work provides useful genetic information for the development of bioaugmentation techniques and reports new bacteria for bioremediation processes transforming IBU into less toxic metabolic compounds.

2023-07-12Master thesis

Embargoed access

Biodegradation of 17α-Ethinylestradiol by strains of Aeromonas Genus isolated from acid mine drainage

Publication . Da Luz Palma, Tânia Cristina; Costa, Maria Clara

17α-ethinylestradiol (EE2), a synthetically derived analogue of endogenous estrogen, is widely employed as a hormonal contraceptive and is recognized as a highly hazardous emerging pollutant, causing acute and chronic toxic effects on both aquatic and terrestrial organisms. It has been included in the initial Water Watch List. The aim of this study was to isolate bacteria from consortia recovered from mine sediments and acid mine drainage samples, both considered extreme environments, with the ability to degrade EE2. From the most promising consortia, isolates affiliated with the Aeromonas, Rhizobium, and Paraburkholderia genera were obtained, demonstrating the capability of growing at 50 mg/L EE2. Subsequently, these isolates were tested with 9 mg/L of EE2 as the sole carbon source. Among the isolated strains, Aeromonas salmonicida MLN-TP7 exhibited the best performance, efficiently degrading EE2 (95 ± 8%) and reaching concentrations of this compound below the limits of detection within 7 and 9 days. The final metabolites obtained are in accordance with those of the TCA cycle; this may indicate EE2 mineralization. As far as is known, Aeromonas salmonicida was isolated for the first time and identified in acid mine drainage, demonstrating its capacity to degrade EE2, making it a promising candidate for bioaugmentation and suggesting its possible applicability in low pH environments.

2024-02-01Journal article

Open access