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- Biodegradation of fluoroquinolones by single bacteriaPublication . Amorim, Catarina L.; Moreira, Irina S.; Maia, Alexandra; Tiritan, Maria E.; Castro, Paula M. L.
- Pharmaceuticals biodegradation by activated sludge and pure culturesPublication . Bessa, Vânia S.; Moreira, Irina S.; Maia, Alexandra S.; Tiritan, Maria E.; Castro, Paula M. L.The occurrence of pharmaceuticals in the environment have been a topic of increasing concern. Most of the pharmaceuticals are not completely mineralized in the human body and are released on the sewage systems as the pharmaceutical itself and as their “biologically active” metabolites through excretion, as well as by improper elimination and disposal. Once current wastewater treatment plants (WWTPs) are not designed to remove these emerging pollutant, they are easily released into the environment.The effects of halogen on biological properties of molecules have had a marked impact on various fields such as pharmacology. It can improve metabolic stability, bioavailability and interactions with the biological target. However, it also increases the recalcitrance of the molecule to biotic and abiotic degradation. Ciprofloxacin (CPF) and Diclofenac (DCF) are two widely used halogenated pharmaceuticals, commonly found in the environment in concentrations that can range ng L−1 to mg L−1. CPF is a common human and veterinary broad-spectrum fluoroquinolone antibiotic. DCF is a non-steroidal anti-inflammatory drug (NSAID), also used as analgesic and antithermic treatment. In the present study, biodegradation of CPF and DCF was assessed by selective enrichements with actived sludge and with pure cultures of three different strains - Labrys portucalensis (F11) and two Rhodococcus spp. (FP1 and S2) – which had previously demonstrated capacity to degrade a range of halogenated compounds. For CPF selective enrichments, a degradation of 100% was achived after 206 days, although without fluoride release. These findings indicate that these selective enrichments are good candidates to find a bacterial strain able to biodegrade CPF. Regarding the pure cultures, F11 exhibited the highest degradation capacity (57%) after 62 days, but also without fluoride release. Concerning DCF selective enrichments, it was released 68% of the stoichiometrically expected cloride ion behind 131 days. In the experiments with pure cultures, F11 and S2, was released the totality of the stoichiometrically expected cloride, elapsed 131 days. These results indicate that these two strains are promising for DCF biodegradation.
- Biodegradation of ofloxacin, norfloxacin, and ciprofloxacin as single and mixed substrates by Labrys portucalensis F11Publication . Amorim, Catarina L.; Moreira, Irina S.; Maia, Alexandra S.; Tiritan, Maria E.; Castro, Paula M. L.Fluoroquinolone (FQ) antibiotics are extensively used both in human and veterinary medicine, and their accumulation in the environment is causing an increasing concern. In this study, the biodegradation of the three most worldwide used FQs, namely ofloxacin, norfloxacin, and ciprofloxacin, by the fluoroorganic-degrading strain Labrys portucalensis F11 was assessed. Degradation occurred when the FQs were supplied individually or as mixture in the culture medium, in the presence of an easily degradable carbon source. Consumption of individual FQs was achieved at different extents depending on its initial concentration, ranging from 0.8 to 30 μM. For the lowest concentration, total uptake of each FQ was observed but stoichiometric fluoride release was not achieved. Intermediate compounds were detected and identified by LC-MS/MS with a quadrupole time of flight detector analyzer. Biotransformation of FQs by L. portucalensis mainly occurred through a cleavage of the piperazine ring and displacement of the fluorine substituent allowing the formation of intermediates with less antibacterial potency. FQ-degrading microorganisms could be useful for application in bioaugmentation processes towards more efficient removal of contaminants in wastewater treatment plants.
- Biodegradation of the fluorinated antibiotic moxifloxacinPublication . Carvalho, Maria F.; Maia, Alexandra; Tiritan, Maria E.; Castro, Paula M. L.
- Chiral analysis of pesticides and drugs of environmental concern: biodegradation and enantiomeric fractionPublication . Maia, Alexandra S.; Ribeiro, Ana R.; Castro, Paula M. L.; Tiritan, Maria ElizabethThe importance of stereochemistry for medicinal chemistry and pharmacology is well recognized and the dissimilar behavior of enantiomers is fully documented. Regarding the environment, the significance is equivalent since enantiomers of chiral organic pollutants can also differ in biodegradation processes and fate, as well as in ecotoxicity. This review comprises designed biodegradation studies of several chiral drugs and pesticides followed by enantioselective analytical methodologies to accurately measure the enantiomeric fraction (EF). The enantioselective monitoring of microcosms and laboratory-scale experiments with different environmental matrices is herein reported. Thus, this review focuses on the importance of evaluating the EF variation during biodegradation studies of chiral pharmaceuticals, drugs of abuse, and agrochemicals and has implications for the understanding of the environmental fate of chiral pollutants.
- Integrated liquid chromatography method in enantioselective studies: biodegradation of ofloxacin by an activated sludge consortiumPublication . Maia, Alexandra S.; Castro, Paula M. L.; Tiritan, M. E.tOfloxacin is a chiral fluoroquinolone commercialized as racemate and as its enantiomerically pure formlevofloxacin. This work presents an integrated liquid chromatography (LC) method with fluorescencedetection (FD) and exact mass spectrometry (EMS) developed to assess the enantiomeric biodegradationof ofloxacin and levofloxacin in laboratory-scale microcosms. The optimized enantioseparation condi-tions were achieved using a macrocyclic antibiotic ristocetin A-bonded CSP (150 × 2.1 mm i.d.; particlesize 5 m) under reversed-phase elution mode. The method was validated using a mineral salts mediumas matrix and presented selectivity and linearity over a concentration range from 5 g L−1(quantificationlimit) to 350 g L−1for each enantiomer. The method was successfully applied to evaluate biodegrada-tion of ofloxacin enantiomers at 250 g L−1by an activated sludge inoculum. Ofloxacin (racemic mixture)and (S)-enantiomer (levofloxacin) were degraded up to 58 and 52%, respectively. An additional degrad-able carbon source, acetate, enhanced biodegradation up to 23%. (S)-enantiomer presented the highestextent of degradation (66.8%) when ofloxacin was supplied along with acetate. Results indicated slightlyhigher biodegradation extents for the (S)-enantiomer when supplementation was done with ofloxacin.Degradation occurred faster in the first 3 days and proceeded slowly until the end of the assays. Thechromatographic results from LC-FD suggested the formation of the (R)-enantiomer during levofloxacinbiodegradation which was confirmed by LC–MS with a LTQ Orbitrap XL.