Browsing by Author "Anselmo, Ana"
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- Destoxificação de águas de cozedura da cortiça em reactor biológicoPublication . Mendonça, E.; Anselmo, AnaO sector corticeiro em portugal, maior produtor mundial de cortiça, enfrenta diversos problemas ambientais, nomeadamente a produção de águas residuais com eleveda carga poluente pelas empresas preparadoras tradicionais, na operação de cozedura da cortiça. As águas de cozedura da cortiça têm elevada carga orgânica, elevado teor de sólidos suspensos e baixo valor de pH. A sua toxicidade e baixa biodegradabilidade estão associadas à presença de compostas naturais fenólicos e polifenólicos. Com base nestas características realizou-se um estudo de destoxificação por método biológico, utilizando o fungo filamentoso Fusarium flociferum. O sistema consistiu num reactor do tipo coluna com borbulhamneto de ar, em cultura contínua, estabelecendo-se um tempo de retençãp hidrúlico de 24 horas. Realizaram-se ensaios com e sem controlo de pH e com e sem adição de carvão activado. Estes ensaios demonstraram a capacidade degradativa deste fungo, sendo de salientar a diminuição da carga orgânica e da toxicidade e o aumento do pH. Representando a descarga destas águas residuais um problema ambiental e dada a inexistência de tecnologias de tratamento adequadas ao sector, estes resultados podem contribuir para a solução do problema num contexto de desenvolvimento sustentável.
- Functional screening of a metagenomic library obtained from soils water of S. Domingos's minePublication . Pereira, Paula Sá; Baeta-Hall, Lina; Sàágua, M. C.; Paixão, Susana M.; Duarte, José Cardoso; Anselmo, Ana
- Metals recovery from mine lead concentrates:screening of bioleaching microbial communitiesPublication . Duarte, José Cardoso; Sàágua, M. C.; Paixão, Susana M.; Baeta-Hall, Lina; Nogueira, Carlos; Pereira, Paula Sá; Anselmo, Ana
- A microcosm approach to evaluate the degradation of tributyltin (TBT) by Aeromonas molluscorum Av27 in estuarine sedimentsPublication . Cruz, Andreia; Henriques, Isabel; Sousa, Ana C. A.; Baptista, Inês; Almeida, Adelaide; Takahashi, Shin; Tanabe, Shinsuke; Correia, Antonio; Suzuki, Satoru; Anselmo, Ana; Mendo, SóniaTributyltin (TBT) is a biocide extremely toxic to a wide range of organisms, which has been used for decades in antifouling paints. Despite its global ban in 2008, TBT is still a problem of great concern due to the high levels trapped in sediments. Aeromonas molluscorum Av27 is a TBT degrading bacterium that was isolated from an estuarine system. We investigated the ability and the role of this bacterium on TBT degradation in this estuarine system, using a microcosm approach in order to mimic environmental conditions. The experiment was established and followed for 150 days. Simultaneously, changes in the indigenous bacterial community structure were also investigated. The results revealed a maximum TBT degradation rate of 28% accompanied by the detection of the degradation products over time. Additionally, it was observed that TBT degradation was significantly enhanced by the presence of Av27. In addition a significantly higher TBT degradation occurred when the concentration of Av27 was higher. TBT degradation affected the bacterial community composition as revealed by the changes in the prevalence of Proteobacteria subdivisions, namely the increase of Deltaproteobacteria and the onset of Epsilonproteobacteria. However, the addition of Av27 strain did not affect the dominant phylotypes. Total bacterial number, bacterial biomass productivity, 16S rRNA gene and denaturing gradient gel electrophoresis (DGGE) analyses also indicated alterations on the bacterial community structure over time, with bacteria non-tolerant to pollutants increasing their representativeness, as, for instance, the increase of the number of Alphaproteobacteria clones from 6% in the beginning to 12% at the end of the experiment. The work herein presented confirms the potential of Av27 strain to be used in the decontamination of TBT-polluted environments.
- Selection of indigenous acidophilic bacteria for the bioleaching of two SOMINCOR concentratesPublication . Paixão, Susana M.; Nogueira, Carlos; Baeta-Hall, Lina; Sàágua, M. C.; Pereira, Paula Sá; Duarte, José Cardoso; Anselmo, Ana
- Sulphate-reducing bacteria from mining environments for metals bioremediationPublication . Paixão, Susana M.; Baeta-Hall, Lina; Barreiros, M. Alexandra; Anselmo, Ana; Duarte, José Cardoso; Sàágua, M. C.Toxic heavy metals and metalloids constitute an international pollution problem that not only impacts public health but also is of environmental and economic importance. Several conventional treatment technologies for removing metals are available. These techniques, based on chemical methods of neutralisation and precipitation, even though quick and effective, present several disadvantages, such as the need for building additional treatment plants, the high cost of the chemical reagents used and the generation of an important volume of sludge which need further treatment. Prokaryotes with physiological activity of sulphate reduction are found in several environmental sites containing metals and these microorganisms have developed several different strategies for detoxification and resistance to toxic elements that are potentially useful for bioremediation. Since sulphate-reducing bacteria (SRB) are found in a large number of contaminated sites containing toxic metals, it is apparent that these organisms have a functional defence system that enables them to persist and even grow under metal stress. The enzymatic metal reduction by SRB offers an alternative to chemical processes to remediate environments containing metals. Acid mine drainage (AMD) is one of the most important source of heavy metal environmental pollution. AMD is characterised by its high acidity (≤3), high concentration of metals (e.g. Cu, Fe, Zn, A1, Pb, As and Cd) and high concentration of dissolved sulphates (≥3000 ppm). Taking advantage of the fact that SRB are present in these mining environments, several samples were collected from S. Domingos abandoned mine (Portugal) and screened for their ability to sulphate reduction, metal resistance and bioremediation. In this context, the most promising consortium of SRB (SRB no. 6) was grown in matrices column reactors, using lactate and ethanol as an electron donor source for the production of H2S from sulphates. Metal resistance was tested in batch using different metal concentration for Cu, Zn and Fe. The results obtained for this SRB inoculum, showed 97% of sulphate reduction (3750—350 mg/l) in the reactors, and a metal tolerance to Fe, Cu and Zn, at concentrations until 260 mg/l, 40 mg/l and 80 mg/l, respectively, in the batch assays, being observed a sulphate reduction (2000—0 mg/l) and a significant metals concentration decrease in the growth medium. Further studies are being carried out to apply this mining inoculum for the design of reactors for AMD bioremediation
- Tributyltin (TBT): a review on microbial resistance and degradationPublication . Cruz, Andreia; Anselmo, Ana; Suzuki, Satoru; Mendo, SóniaTributyltin (TBT) is one of the most toxic xenobiotics ubiquitous in the aquatic environment. Several reports have described the negative impact of TBT in living organisms, from bacteria to mammals. Over the world, TBT contamination has being described as a serious problem. Thus, it is imperative to decontaminate TBT polluted sites. Bioremediation strategies may constitute an alternative to conventional decontamination methods, benefiting from the microorganisms potential to metabolize xenobiotics. Several microorganisms among bacteria, fungus, and algae have been reported to possess the ability to resist and, in certain cases, degrade TBT in their simple and less toxic derivatives. Due their characteristics, some of those microorganisms have been used for bioremediation studies and to construct bioreporters to detect TBT in the environment. This review provides an overview regarding microbial TBT resistance, while focusing on TBT degradation and bioremediation. A comprehensive revision on the several applications of organotin compounds, adverse biological effects on living organisms, and information regarding the available TBT bioreporters is also included.