Browsing by Author "Afonso, Carlos M. M."
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- Bioaugmentation for treating transient 4-fluorocinnamic acid shock loads in a rotating biological contactorPublication . Amorim, Catarina L.; Duque, Anouk F.; Afonso, Carlos M. M.; Castro, Paula M. L.A rotating biological contactor (RBC) was used to treat shock loadings of 4-fluorocinnamic acid (4-FCA). Intermittent 4-FCA shocks of 35 mg L-1 were applied (ca. 3 months) with only limited mineralization occurring and accumulation of 4-fluorobenzoate (4-FBA) as an intermediate. After bioaugmentation with a degrading bacterium the RBC was able to deal with 4-FCA intermittent loading of 80 mg L-1 however, a gradual decline in RBC performance occurred, leading to 4-FBA accumulation. The degrading strain was recovered from the biofilm during 2 months but intermittent feeding may have led to diminishing strain numbers. Distinct bacterial communities in the 1st and the 5th and 10th stages of the RBC were revealed by denaturating gradient gel electrophoresis. Several isolates retrieved from the RBC transformed 4-FCA into 4-FBA but only two strains mineralized the compound. Bioaugmentation allowed removal of the fluorinated compound however intermittent feeding may have compromised the bioreactor efficiency.
- Biodegradation of fluoroanilines by the wild strain Labrys portucalensisPublication . Amorim, Catarina L.; Carvalho, Maria F.; Afonso, Carlos M. M.; Castro, Paula M. L.Aniline and halogenated anilines are known as widespread environmental toxic pollutants released into soil and water. In contrast to aniline, which is rapidly metabolized via catechol, halosubstituted anilines are more resistant to microbial attack. A fluorobenzene-degrading bacterium, Labrys portucalensis strain F11, was tested under different culture conditions for the degradation potential towards 2-, 3- and 4-fluoroaniline (2-, 3- and 4-FA). Strain F11 was able to use FAs as a source of carbon and nitrogen however, supplementation with a nitrogen source improved substrate consumption and its dehalogenation extent. When F11 cells were previously grown on fluorobenzene (FB), higher biodegradation rates were achieved for all isomers. Complete 2-FA biodegradation with stoichiometric fluoride release was achieved when FB-induced cells were used. On the other hand, the degradation of 3- and 4-FA was characterized by incomplete defluorination of the target compounds suggesting accumulation of fluorinated intermediates. F11 cultures simultaneously supplied with FB and the fluorinated anilines showed a concomitant degradation of both substrates, suggesting co-metabolic biodegradation. To our knowledge, this is the first time that biodegradation of 2- and 3-FA as a sole carbon and nitrogen source and co-metabolic degradation of FA isomers in the presence of a structural analogous compound is reported.
- Biosorption of fluoroquinolones by activated sludge and aerobic granules sludgePublication . Ferreira, Vanessa R. A.; Amorim, Catarina L.; Cravo, Sara M.; Tiritan, Maria E.; Castro, Paula M. L.; Afonso, Carlos M. M.Antibiotic residues have been detected in various environmental matrices, such as surface water and even drinking water. Although present at low levels (μg/L, ng/L), many antibiotics are bioaccumulative, pseudo-persistent and can promote resistance/alterations in bacterial populations [1]. Recent studies on antibiotics removal by activated sludge (AS) and aerobic granules (AGS) show biosorption as the dominant process, determining the fate of these micropollutants [2-3]. In this work the biosorption of three widely used fluoroquinolones (FQ) - ofloxacin (OFL), norfloxacin (NOR) and ciprofloxacin (CPF) - to AS and AGS was evaluated. A High Performance Liquid Chromatography with Fluorescence Detection (HPLC-FD) method was validated and used to follow the biosorption of the target FQ. Data obtained in this study contribute to a better comprehension of FQ biosorption behavior in AS and AGS. At pH 7 AS showed better performance to biosorb OFL, NOR and CPF than AGS. The higher biosortion capacity of AS was probably due to the negative charge on its surface, evaluated by a zeta potential of -25.65 mV, at pH 7. OFL was the less biosorbed, both onto AS and AGS, because this FQ at pH 7 is mainly present in its anionic form. The equilibrium data for AS showed a better fit to the Langmuir model, while the model that presented better fit for AGS was the Freundlich model. The FQ could be desorbed from AGS at pH 3, pH 8 and pH 9 whereas at pH 4 the biosorption process was promoted.
- Degradation of fluoroanilines by the wild strain Labrys portucalensisPublication . Amorim, Catarina L.; Carvalho, Maria F.; Afonso, Carlos M. M.; Castro, Paula M. L.Aromatic amine compounds, many of them with halogenated substituents, constitute a major class of environmental pollutants that have been released into soil and water due to extensive use in industries and agriculture. Biodegradation has been found to be a major route for the removal of this kind of toxic and recalcitrant pollutants from the environment. Whereas the degradation of mono- and dichlorinated anilines has been studied, very little is known about fluorinated anilines. Therefore, the objective of this study was to investigate, under aerobic conditions, the degradation of 2-, 3- and 4-fluoroaniline by a previously isolated pure bacterium, designated as strain F11. This microorganism, identified as Labrys portucalensis, was isolated from a contaminated site in northern Portugal and has the unique capacity to utilize fluorobenzene as a sole carbon and energy source,. The results of the biodegradation of 2-, 3- and 4-fluoroaniline by strain F11 showed that this microorganism is able to completely degrade 2- fluoroaniline and partially degrade 4-fluoroaniline, when these compounds are present as a sole carbon and energy source. Biodegradation of these two compounds also occurred, although at a lower rate, in the absence of an external nitrogen source in the culture medium. To our knowledge, this is the first study reporting the biodegradation of 2- and 4-fluoroaniline as a sole carbon and energy source by a pure microbial culture. C.L. Amorim and M.F. Carvalho wish to acknowledge a research grant from Fundação para a Ciência e Tecnologia (FCT), Portugal (Ref. SFRH/BD/47109/2008 and SFRH/BPD/44670/2008, respectively) and Fundo Social Europeu (III Quadro Comunitário de Apoio). This work was supported by the FCT Project - PTDC/BIO/67306/2006
- Fluoroquinolones biosorption onto microbial biomass: activated sludge and aerobic granular sludgePublication . Ferreira, Vanessa R.A.; Amorim, Catarina L.; Cravo, Sara M.; Tiritan, M. E.; Castro, P. M. L.; Afonso, Carlos M. M.Fluoroquinolones (FQs) have been reported in trace amounts in different environmental matrices. The biosorption of three most prescribed FQs, ofloxacin (OFL), norfloxacin (NOR) and ciprofloxacin (CPF) by activated sludge (AS) and aerobic granular sludge (AGS) was investigated. Biosorption assays were conducted with FQs concentrations within the range of 100e700 ng mL 1, to mimic environmental conditions. At neutral pH and at the end of 48 h, AS showed higher biosorption capacity than AGS. For AS, a maximum biosorption of 1.50 ± 0.03, 3.24 ± 0.05 and 3.39 ± 0.06 mg gTSS 1 was observed for OFL, NOR and CPF respectively, whereas for AGS the maximum amount of FQs biosorbed was 1.18 ± 0.03, 2.73 ± 0.02 and 2.94 ± 0.03 mg gTSS 1. Langmuir isotherm was more applicable for describing FQs biosorption equilibrium by AS while for AGS, the Freundlich isotherm was more adequate. Given the AGS technology innovative character, the effect of change of pH on the biosorbed FQs was evaluated. FQs could be desorbed from AGS at pH 3, pH 8 and pH 9 but at pH 4 the biosorption process was promoted. This study allows a better understanding of the FQs biosorption processes. Moreover, the data from biosorption/desorption from AGS may be useful for management and operation of AGS bioreactors
- Microbial degradation of 17β -estradiol and 17α -ethinylestradiol followed by a validated HPLC-DAD methodPublication . Ribeiro, Ana R.; Carvalho, Maria F.; Afonso, Carlos M. M.; Tiritan, Maria E.; Castro, Paula M.L.This work aimed at studying the biodegradation of two estrogens, 17agr -estradiol (E2) and 17β -ethinylestradiol (EE2), and their potential metabolism to estrone (E1) by microbial consortia. The biodegradation studies were followed by High Performance Liquid Chromatography-Diode Array Detector (HPLC-DAD) using a specifically developed and validated method. Biodegradation studies of the estrogens (E2 and EE2) were carried out with activated sludge (consortium A, CA) obtained from a Wastewater Treatment Plant (WWTP) and with a microbial consortium able to degrade recalcitrant compounds, namely fluorobenzene (consortium B, CB). E2 was more extensively degraded than EE2 by CA whereas CB was only able to degrade E2. The addition of acetate as a supplementary carbon source led to a faster biodegradation of E2 and EE2. E1 was detected as a metabolite only during the degradation of E2. The 16S rRNA gene sequence analyses of strains recovered from the degrading cultures revealed the presence of the genera Pseudomonas, Chryseobacterium and Alcaligenes. The genera Pseudomonas and Chryseobacterium were retrieved from cultures supplied with E2 and EE2, while the genus Alcaligenes was found in the presence of E2, suggesting that they might be involved in the degradation of these compounds.
- Mineralization of 4-fluorocinnamic acid by a Rhodococcus strainPublication . Amorim, Catarina L.; Ferreira, António César Silva; Carvalho, M.F.; Afonso, Carlos M. M.; Castro, Paula M.L.A bacterial strain capable of aerobic degradation of 4-fluorocinnamic acid (4-FCA) as the sole source of carbon and energy was isolated from a biofilm reactor operating for the treatment of 2-fluorophenol. The organism, designated as strain S2, was identified by 16S rRNA gene analysis as a member of the genus Rhodococcus. Strain S2 was able to mineralize 4-FCA as sole carbon and energy source. In the presence of a conventional carbon source (sodium acetate [SA]), growth rate of strain S2 was enhanced from 0.04 to 0.14 h−1 when the culture medium was fed with 0.5 mMof 4- FCA, and the time for complete removal of 4-FCA decreased from 216 to 50 h.When grown in SA-supplemented medium, 4-FCA concentrations up to 1 mM did not affect the length of the lag phase, and for 4-FCA concentrations up to 3 mM, strain S2 was able to completely remove the target fluorinated compound. 4-Fluorobenzoate (4-FBA) was transiently formed in the culture medium, reaching concentrations up to 1.7 mM when the cultures were supplemented with 3.5mMof 4-FCA. Trans,trans-muconate was also transiently formed as a metabolic intermediate. Compounds with molecular mass compatible with 3-carboxymuconate and 3-oxoadipate were also detected in the culture medium. Strain S2 was able to mineralize a range of other haloorganic compounds, including 2- fluorophenol, to which the biofilm reactor had been exposed. To our knowledge, this is the first time that mineralization of 4-FCA as the sole carbon source by a single bacterial culture is reported.
- Remoção de fluoroquinolonas do ambiente: biossorção a lamas ativadas e a grânulos aeróbiosPublication . Ferreira, Vanessa R. A.; Amorim, Catarina L.; Cravo, Sara M.; Tiritan, Maria E.; Castro, Paula M. L.; Afonso, Carlos M. M.Diversas matrizes ambientais, particularmente águas residuais, têm revelado a presença de antibióticos. Embora presentes em níveis vestigiais (ng.L-1 a µg.L-1,), estes compostos são pseudo-persistentes e, naquelas concentrações, podem também promover resistências nas populações bacterianas [1]. Estudos recentes de remoção de antibióticos com lamas ativadas (AS) e grânulos aeróbios (AGS) mostram a biossorção como processo dominante e eficaz na remoção destes micropoluentes [2,3]. O presente trabalho explorou a biossorção de três fluoroquinolonas (FQ) - ofloxacina (OFL), norfloxacina (NOR) e ciprofloxacina (CPF) - a AS e AGS. Com vista a uma melhor compreensão dos fenómenos que ocorrem durante o processo, foram estudados diversos parâmetros que condicionam a biossorção. As AS demonstraram melhor desempenho na remoção da OFL, NOR e CPF relativamente aos AGS. No entanto, nas concentrações estudadas, não foi possível promover a remoção total dos fármacos. A capacidade mais elevada de biossorção das AS foi atribuída à carga negativa da superfície da biossorção, representada por um potencial zeta de -25,65 mV, a pH 7. A OFL foi a FQ menos removida, tanto pelas AS como pelos AGS, porque a OFL a pH 7 está principalmente presente na forma aniónica, com uma pequena percentagem, na forma zwiteriónica. Em AGS verifica-se um aumento da biossorção da OFL, NOR e CPF em pH ácido (pH 4) e maior dessorção em pH alcalino (pH 8 a 9). Observou-se também que ocorre a destruição da estrutura granular dos AGS quando o pH do meio é igual ou inferior a 3. Os resultados obtidos neste estudo contribuem para uma utilização mais eficaz de AS e AGS na remoção de antibióticos fluoroquinolonas do ambiente.
- Studies on the biodegradation of fluoroanilines by a single microorganismPublication . Amorim, Catarina L.; Carvalho, Maria F.; Afonso, Carlos M. M.; Castro, Paula M. L.Aromatic amines are considered important environmental pollutants due to their toxic and recalcitrant properties. The widespread use of these compounds in the industry and agriculture has led to their release to soils and waters. Microbial degradation has been found to be the major mechanism to avoid the accumulation of these pollutants in the environment. Literature studies on the biodegradation of halogenated anilines have mostly focused on chlorinated anilines and very little is known about utilization of fluorinated derivatives. This study focuses on the biodegradation of 2-, 3- and 4-fluoroaniline by a microbial strain (strain F11) identified as Labrys portucalensis. This microorganism has the capacity to degrade aerobically fluorobenzene as sole carbon and energy source. Non-induced cells and cells induced in fluorobenzene were used to examine the capacity of the degrading strain to metabolize the target compounds. Co-metabolic studies with fluorobenzene were also conducted. The experiments were run in batch mode at 25ºC with constant shaking. Growth, depletion of the target compounds and fluoride release were monitored. Strain F11 was capable to completely degrade 2-fluoroaniline. 3- and 4-fluoroaniline were degraded nearly to completion by F11 cultures induced with fluorobenzene and by cultures fed simultaneously with fluorobenzene. The fluoride liberation for those two fluorinated anilines occurred at different extents. C.L. Amorim and M.F. Carvalho wish to acknowledge a research grant from Fundação para a Ciência e Tecnologia (FCT), Portugal (Ref. SFRH/BD/47109/2008 and SFRH/BPD/44670/2008, respectively) and Fundo Social Europeu (III Quadro Comunitário de Apoio). This work was supported by the FCT Project - PTDC/BIO/67306/2006