Dulce Brito

Modelling the biodegradation of non-steroidal anti-inflammatory drugs (NSAIDs) by activated sludge and a pure culture.

A model describing ibuprofen and ketoprofen biodegradation by activated sludge from three different wastewater treatment plants (WWTP) was developed in this study. This model successfully described the biodegradation profiles observed at two different initial concentrations of each compound, where a lag-phase was observed prior to the biodegradation of each compound. Twelve ibuprofen and ketoprofen degrading isolates were identified in this study from the WWTP sludge showing the best removal performance. One of these isolates was characterised via another model, where biodegradation was dependent on biomass growth rate as well as the ibuprofen concentration. The fact that different models were needed to describe the biodegradation by activated sludge and a pure culture suggests that the biodegradation of non-steroidal anti-inflammatory drugs (NSAIDs) depends on the microbial community, thus pharmaceutical biodegradation models may require adaptation depending upon the system. This study provides an advance towards modelling pharmaceutical biodegradation in WWTPs.

Unveiling the fungal mycobiota present throughout the cork stopper manufacturing process

A particular fungal population is present in the main stages of the manufacturing process of cork discs. Its diversity was studied using both dependent (isolation) and independent culture methods (denaturing gel gradient electrophoresis and cloning of the ITS1-5.8S-ITS2 region). The mycobiota in the samples taken in the stages before and after the first boiling seems to be distinct from the population in the subsequent manufacturing stages. Most isolated fungi belong to the genera Penicillium, Eurotium and Cladosporium. The presence of uncultivable fungi, Ascomycota and endophytes in raw cork was confirmed by sequencing. The samples taken after the first boiling contained uncultivable fungi, but in a few samples some isolated fungi were also detected. The main taxa present in the following stages were Chrysonilia sitophila, Penicillium glabrum and Penicillium spp. All applied techniques had complementary outcomes. The main factors driving the shift in cork fungal colonization seem to be the high levels of humidity and temperature to which the slabs are subjected during the boiling process.

Metabolite identification of ibuprofen biodegradation by Patulibacter medicamentivorans under aerobic conditions

ABSTRACT Ibuprofen (IBU) is a non-steroidal anti-inflammatory drug that is becoming increasingly recognized as an important micropollutant to be monitored in wastewater treatment plants (WWTP), since it has been detected in effluents at the µg L−1 level. The IBU metabolites from biological degradation are not completely understood and can represent a threat to natural aquatic systems. P. medicamentivorans was previously isolated from WWTP sludge and found to be capable of IBU degradation. The aerobic biodegradation of ibuprofen by this organism was investigated in a batch lab-scale reactor for the identification of the metabolites formed. The metabolites were analysed and putatively identified by HPLC-DAD-MS/MS and GC-MS and biodegradation pathways were proposed. The toxicity and the biodegradability potential of the metabolites were also investigated. The results showed that IBU biotransformation was achieved by hydroxylation followed by the formation of a carboxylic acid in the IBU molecule and by the formation of a catechol, allowing the aromatic ring cleavage. Two biodegradation pathways were proposed: in one, the metabolites generated from the enzymatic action correspond to a less biodegradable chemical structure of the intermediate products (isobutylbenzene and 3-isobutylphenol), with comparatively higher toxicity; in the other mechanism, more oxidable chemical structures were formed with less toxicity and higher biodegradability. This suggests that the biodegradation of IBU by P. medicamentivorans can take place by more than one mechanism regarding the enzymes formed by this Gram-positive bacterium, with subsequent oxidation of the parent compound to overall more soluble and less toxic compounds to fish, daphnia and green algae. GRAPHICAL ABSTRACT