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- 2-Fluorophenol degradation by aerobic granules in a sequencing batch reactorPublication . Duque, A. F.; Bessa, V. S.; Carvalho, M. F.; De Kreuk, M. K.; Loosdrecht, M. C. M. van; Castro, P. M. L.
- Isolation and characterization of a bacterial strain able to degrade 2-FluorophenolPublication . Duque, A. F.; Carvalho, M. F.; Janssen, D. B.; Castro, P. M. L.
- Bioaugmentation of a rotating biological contactor with a bacterial strain able to degrade fluorinated phenolsPublication . Duque, A. F.; Bessa, Vânia S.; Carvalho, M. F.; Castro, P. M. L.
- Biological treatment of a contaminated gaseous emission from a leather industry in a suspended-growth bioreactorPublication . Carvalho, M. F.; Duque, A. F.; Moura, S. C.; Amorim, Catarina L.; Ferreira Jorge, R. M.; Castro, Paula M. L.A suspended-growth bioreactor (SGB) was operated for the treatment of a gaseous stream mimicking emissions generated at a leather industrial company. The main volatile organic compounds (VOCs) present in the gaseous stream consisted of 1-methoxy-2-propanol, 2,6-dimethyl-4-heptanone, 2-butoxyethanol, toluene and butylacetate. A microbial consortium able to degrade these VOCs was successfully enriched. A laboratory- scale SGB was established and operated for 210-d with an 8 h cycle period and with shutdowns at weekends. Along this period, the SGB was exposed to organic loads (OL) between 6.5 and 2.3 £ 102 g h¡1 m¡3. Most of the compounds were not detected at the outlet of the SGB. The highest total VOC removal efficiency (RE) (ca 99%) was observed when an OL of 1.6 £ 102 g h¡1 m¡3 was fed to the SGB. The maximum total VOC elimination capacity (1.8 £ 102 g h¡1 m¡3) was achieved when the OL applied to the SGB was 2.3 £ 102 g h¡1 m¡3. For all the operating conditions, the SGB showed high levels of degradation of toluene and butylacetate (RE t 100%). This study also revealed that recirculation of the gaseous effluent improved the performance of the SGB. Overall, the SGB was shown to be robust, showing high performance after night and weekend shutdown periods.
- Biodegradation of 2-fluorophenol in a rotating biological contactorPublication . Duque, A. F.; Bessa, V. S.; Franco, A. R.; Carvalho, M. F.; Castro, P. M. L.
- Isolation and initial characterization of a bacterial consortium able to mineralize fluorobenzenePublication . Carvalho, M. F.; Alves, C. C. T.; Ferreira, M. I. M.; Marco, P. De; Castro, P. M. L.Fluorinated compounds are known to be more resistant to microbial degradation than other halogenated chemicals. A microbial consortium capable of aerobic biodegradation of fluorobenzene (FB) as the sole source of carbon and energy was isolated by selective enrichment from sediments collected in a drain near an industrial site. A combination of three microbial strains recovered from the enriched consortium was shown to be necessary for complete FB mineralization. Two of the strains (F1 and F3) were classified by 16S rRNA analysis as belonging to the Sphingobacterium/Flavobacterium group, while the third (F4) falls in the -Proteobacteria group, clustering with Alcaligenes species. Strain F4 was consistently found in the liquid cultures in a much greater proportion than strains F1 and F3 (86:8:6 for F4, F1, and F3, respectively). Stoichiometric release of fluoride ions was measured in batch and fed-batch cultures. In batch cultures, the consortium was able to use FB up to concentrations of 400 mg liter 1 and was able to utilize a range of other organic compounds, including 4-fluorophenol and 4-fluorobenzoate. To our knowledge this is the first time biodegradation of FB as a sole carbon source has been reported.
- Production of 4-fluorocatechol from fluorobenzene by the wild srain Labrys portucalensisPublication . Moreira, I. S.; Carvalho, M. F.; Amorim, Catarina L.; Afonso, C M. M.; Janssen, D. B.; Castro, P. M. L.
- Bacterial degradation of moxifloxacin in the presence of acetate as a bulk substratePublication . Carvalho, M. F.; Maia, A. S.; Tiritan, M. E.; Castro, P. M. L.Fluoroquinolones constitute a group of emerging pollutants and their occurrence in different environmental compartments is becoming object of increasing public concern due to their ecotoxicological effects and the potential to develop resistant bacteria. This study aimed to investigate the biodegradation of moxifloxacin (MOX), for which studies in the literature are very scarce. An activated sludge (AS) consortium and three bacterial strains able to degrade fluoroaromatic compounds e strains F11, FP1 and S2 e were tested. Biodegradation studies were conducted using acetate as a bulk carbon source. Strain F11 showed the highest biodegradation capacity, being able to completely consume and dehalogenate 7.5 mM of the target antibiotic when daily co-supplemented with acetate present as a readily degradable organic substrate in wastewaters. MOX could be used by strain F11 as a sole nitrogen source but the presence of an external nitrogen source in the culture medium was essential for complete biodegradation. Strain F11 was capable of completely consuming MOX in a range between 2 and 11 mM, although stoichiometric fluoride release was not obtained for the highest tested concentration. The antibacterial activity of residual MOX and of the metabolic products potentially resultant from the biodegradation process was investigated by agar diffusion tests, demonstrating that MOX biodegradation is associated with the elimination of the antibacterial properties of the target antibiotic and of the produced metabolites, which is an important result, as the activity of antibiotics and/or their metabolites in the environment, even at low levels, may lead to the development of resistant bacterial strains. Overall, the results obtained in this study suggest that strain F11 is a promising microorganism for the treatment of waters contaminated with MOX, where it could be used for bioaugmentation/bioremediation purposes. To the best of our knowledge, this is the first study reporting complete removal and dehalogenation of MOX by a single microorganism.
- Isolation and properties of a pure bacterial strain capable of fluorobenzene degradation as sole carbon and energy sourcePublication . Carvalho, M. F.; Jorge, R. Ferreira; Pacheco, C. C.; Marco, P. De; Castro, P. M. L.A pure bacterial strain capable of aerobic biodegradation of fluorobenzene (FB) as the sole carbon and energy source was isolated by selective enrichment from sediments collected from a polluted site. 16S rRNA and fatty acid analyses support that strain F11 belongs to a novel genus within the a-2 subgroup of the Proteobacteria, possibly within a new clade related to the order Rhizobiales. In batch cultures, growth of strain F11 on FB led to stoichiometric release of fluoride ion. Maximum experimental growth rate of 0.04 h-1 was obtained at FB concentration of 0.4 mM. Growth kinetics were described by the Luong model. An inhibitory effect with increasing FB concentrations was observed, with no growth occurring at concentrations higher than 3.9 mM. Strain F11 was shown to be able to use a range of other organic compounds, including other fluorinated compounds such as 2-fluorobenzoate, 4-fluorobenzoate and 4-fluorophenol. To our knowledge, this is the first time biodegradation of FB, as the sole carbon and energy source, by a pure bacterium has been reported.
- Degradation of difluorobenzenes by the wild strain Labrys portucalensisPublication . Moreira, I. S.; Carvalho, M. F.; Amorim, Catarina L.; Janssen, D. B.; Castro, Paula M. L.