Rozprawy doktorskie na temat „Depuration”

Syftet med studien var att kartlägga anestesianvändning vid depuration utförd av tandhygienister. Ett ytterligare syfte var att undersöka tandhygienisters anledningar till varför anestesi används eller inte används. En enkätstudie skickades till 148 tandhygienister slumpmässigt utvalda av Sveriges Tandhygienistförening. Nittio enkäter (60,8 %) inkluderades i studiens resultat. Anestesi vid depuration användes främst en till två gånger per vecka med ett medelvärde på 38,6 % (±29,8). Ökat fickdjup resulterade i ökad anestesianvändning vid subgingival rengöring (fickdjup 5-6 mm 43,1 VAS, fickdjup 10< mm 82,4 VAS, Visual Analogue Scale). Anestesiförekomsten var lägre vid avlägsning av supragingival tandsten, fyllningsöverskott samt polering med putspasta. Ytanestesi utan efterföljande injektion var den vanligast förekommande anestesitypen, och den minst använda var mandibularinjektioner. De mest förekommande svaren till varför anestesi används var att ge en smärtfri behandling och att anestesi möjliggör ett bättre utfört arbete. Den vanligaste anledningen till varför anestesi inte används var att patienten avböjer. Det kan ifrågasättas om smärtfri behandling sker tillräckligt ofta, då resultatet tyder på att anestesi används för lite i förhållande till hur mycket depuration som utförs.

PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO
COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
PROGRAMA DE SUPORTE À PÓS-GRADUAÇÃO DE INSTS. DE ENSINO
Estudos prévios relacionam a ocorrência de episódios de mortandade de peixes em corpos hídricos como a Lagoa Rodrigo de Freitas (LRF) com a rápida disponibilização de espécies poluentes e nutrientes naturais na coluna d água especialmente durante altas precipitações de chuva, quando ocorre transbordo dos rios poluídos da bacia sobre a água da Lagoa, ocasionando uma demanda de oxigênio dissolvido maior do que o normal para depuração de tais espécies. Nesse contexto existe interesse em evitar episódios críticos de insuficiência de OD na água dos corpos hídricos que possam advir de tais eventos. Estudos realizados no presente trabalho tiveram como objetivo caracterizar as águas de rios da Sub-bacia hidrográfica da LRF através de DBO, COT, SST, Ptotal no canal a montante de deságue para a Lagoa em períodos de chuva e de tempo seco; e avaliar um possível tratamento que proporcione a depuração acelerada dos poluentes utilizando peróxido de hidrogênio, fornecendo oxigênio para as águas poluídas através do processo de decomposição do oxidante. Avaliaram-se diferentes dosagens de H2O2 em tempo reacional de 24h de acordo com limites de ecotoxicidade conhecidos. Testes realizados em amostras de rio coletadas em dias de baixa precipitação contendo concentrações de DBO de até 2,2 mg/L mostraram uma velocidade de decaimento de H2O2 inferior ao para amostras tanto coletadas também em dia de baixa precipitação porém com elevada DBO (24,0 mg/L), quanto para dia de alta precipitação (13,2 mm em 24 h) com relevante concentração de material orgânico. Observou-se uma dosagem suficiente de 15,0 mg/L para as amostras coletadas em baixa precipitação e alta DBO, e dosagem suficiente de 3,0 mg/L para amostras coletas em maior evento de precipitação (13,2 mm em 24 h), acima das quais, não ocorre mais aumento significativo da velocidade de decaimento da [H2O2] e também de velocidade de contribuição de OD para a água. Concluiu-se que a adição de H2O2 nas águas de rios durante eventos de poluição causados por chuvas intensas ou lançamento de esgoto pode contribuir para evitar episódios críticos de insuficiência de OD em rios poluídos por material orgânico e na pluma de poluentes que pode ser formada por transbordo dos rios para a LRF.
Previous studies have associated the occurrence of episodes of death of fish in water bodies such as the Lagoa Rodrigo de Freitas (LRF) to to the rapid availability of pollutants and natural nutrients in the water column species especially during high rain precipitation events, which occur when the rivers overflow and pollute the water of the lagoon, causing a biochemical oxygen demand higher than usual for the rate of natural depuration of the contaminating species. In this context there is interest in avoiding critical episodes DO deficiency in the water bodies that may arise from such events. Studies conducted in the present work aimed at characterizing the rivers of sub-basin of LRF through BOD, TOC, TSS, Ptotal on the canal that overflows into the lagoon in periods of rain and dry weather; and evaluate a possible treatment offering the accelerated depuration of pollutants using hydrogen peroxide, providing oxygen to the polluted water through the self-decomposition process. The study evaluated the effect of different doses H2O2 in 24 hours of reaction time according to known ecotoxicity limits. In tests on samples collected from rivers in days of little rain containing BOD concentrations up to 2.2 mg / L, H2O2 showed a decay rate lower than those of other samples also collected on days of low precipitation, but with high BOD (24, 0 mg / L), and days of high rainfall (24 hours 13.2 mm), with a significant concentration of dissolved organic contaminants. A maximum sufficient dose of 15.0 mg / L was found for the low and high samples precipitation BOD, and a maximum sufficient dose of 3.0 mg / L for most of the samples collected during the precipitation event (13.2 mm 24 hours), above which there is no significant increase over the rate of decomposition of [H2O2], and the rate of generation of DO in the water. It was concluded that the addition of H2O2 into the waters of rivers during pollution events caused by heavy rains or sewage release can help to avoid critical episodes of DO deficiency in polluted rivers by organic matter and pollutant plume that can be formed by overflow of those rivers to the LRF lagoon.

Doutoramento em Biologia
De forma a reduzir a transmissão de agentes patogénicos através do consumo de bivalves, devem ser desenvolvidas novas tecnologias a associar à depuração, tal como a terapia fágica. A eficácia da utilização de fagos para controlar infeções bacterianas tem sido relatada em diversos estudos. No entanto, relativamente à utilização da terapia fágica para inativar bactérias patogénicas durante a depuração de bivalves, existe apenas um estudo preliminar, feito sem circulação de água (contrariamente ao que acontece na depuração industrial). O sucesso da combinação destas duas tecnologias depende da compreensão detalhada da dinâmica sazonal e espacial da comunidade bacteriana total, incluindo bactérias associadas a doenças devido ao consumo de bivalves e indicadores de qualidade microbiológica da água, nas zonas de produção de bivalves. Durante o Verão, a comunidade bacteriana total apresentou uma maior complexidade e aumento da abundância dos principais grupos de bactérias patogénicas, indicando que deste pode ser um período crítico onde a terapia fágica deve ser aplicada. No entanto, devido ao impacto das fontes de poluição antropogénicas e outras fontes de contaminação, a terapia fágica poderá ter que ser aplicada também durante a estação fria. Cinco novos fagos foram isolados e caracterizados para controlar Salmonella Typhimurium (phSE-1, phSE-2 e phSE-5) e Escherichia coli (phT4A e EC2A), a fim de avaliar a sua potencial aplicação durante a depuração de bivalves. Os ensaios in vitro demonstraram que o uso de fagos individuais (phT4A e EC2A), pode ser uma alternativa eficaz para o controlo de E. coli, em particular, quando combinados em cocktail. A depuração num sistema estático com MOI 1 usando os fagos phT4A e EC2A, foi a condição em que se obteve melhores resultados (diminuição ~2.0 log CFU/g) em berbigões artificialmente contaminados. Quando berbigões naturalmente contaminados foram tratados em sistema estático com as suspensões de fagos individuais e cocktails de fagos, foram obtidas reduções semelhantes na concentração de E. coli (diminuição ~0.7 log UFC/g). Quando os berbigões naturalmente contaminados foram depurados com o fago phT4A com circulação de água, a concentração de bactéria foi reduzida mais rapidamente que na ausência de fagos. Os resultados dos ensaios in vitro mostraram igualmente que o controlo de S. Typhimurium com fagos phSE-5 e phSE-2 e o cocktail destes dois fagos foi eficiente. A aplicação do fago phSE-5 e cocktail (phSE-2/phSE-5) inativou eficazmente S. Typhimurium em berbigões contaminados artificialmente (redução de 1.7 UFC/g com o fago phSE-5 e 0.7 log UFC/g com o cocktail phSE-2/phSE-5) e em berbigões naturalmente contaminados (redução de 0.9 log UFC/g para ambos para a suspensão simples e para o cocktail) durante a depuração em sistema estático, especialmente quando são usadas suspensões do fago phSE-5 a uma MOI baixa. Os berbigões artificialmente contaminados também foram mais eficazmente descontaminados durante a depuração com circulação de água na presença do fago phSE-5 que quando foi usada apenas depuração sem adição de fagos (i.e. o processo convencional de depuração). Este é o primeiro trabalho em que foi testado o uso de fagos durante a depuração de berbigões naturalmente contaminados e contaminados artificialmente em sistemas com circulação de água, tal como acontece na depuração industrial de bivalves, provando assim que esta tecnologia poderá ser transposta para a indústria. Os resultados obtidos usando fagos de E. coli e de S. Typhimurium mostraram que a combinação da terapia fágica e depuração melhora a segurança microbiana dos bivalves para consumo humano, melhorando a eficiência de descontaminação. Além disso, esta abordagem também permite reduzir o tempo necessário para a depuração e consequentemente, os custos a ela associados. No entanto, a seleção e caracterização dos fagos e determinação da MOI mais adequado para ser utilizado durante a terapia fágica, é essencial para o sucesso da terapia fágica no controlo de bactérias patogénicas.
In order to reduce the infections by microbial pathogens through the consumption of bivalves, it is essential to develop alternative approaches to the conventional depuration practices. One new promising approaches is to combine the depuration of bivalves with phage therapy. The use of phages to control bacterial infections has been reported across numerous fields by many researchers. However, relatively the combination of depuration and phage therapy to eliminate pathogenic bacteria in bivalves there is only one study, and this study did not replicate industrial depuration procedures. The successful combination of those two technologies depends on a detailed understanding of the seasonal and spatial dynamics of the overall bacterial communities, including the bacteria implicated in bivalves-related illness and the indicators of microbiological water quality, in the harvesting areas. During the summer, the total bacterial community presented high complexity and an increase of abundance of the main pathogenic bacteria, indicating that this season is the critical time frame when phage therapy should be applied. However, due to the impact anthropogenic and other sources of contamination, phage therapy could be necessary also during the cold season. Five new phages were isolated and characterized to control Escherichia coli (phT4A and ECA2) and Salmonella Typhimurium (phSE-1, phSE-2 and phSE- 5) in order to evaluate their potential application during depuration. The in vitro assays indicated that the use of phages individually (phT4A and EC2A) or combined in cocktails (phT4A/EC2A), can be an effective alternative to control of E. coli, particularly if combined in a phage cocktail. Depuration in static seawater at MOI 1 with phage phT4A and ECA2 revealed to be the best condition (decreased of the 2.0 log CFU/g) in artificially contaminated cockles. When naturally contaminated cockles were treated in static seawater with single phage suspensions and the phage cocktail, similar decreases in the concentration of E. coli (decreased of the 0.7 log CFU/g) were achieved. When naturally contaminated cockles were depurated using conventional practices with phage phT4A, bacterial concentration was reduced sooner. The assays in vitro, demonstrated that the control S. Typhimurium with phages phSE-5 and phSE-2 and with these two phages combined in a cocktail was efficient, paving way for the in vivo studies. The efficiency of bacterial inactivation with single phage suspensions of phSE-5 and phSE-2 leaded to further in vivo studies to control of Salmonella in bivalves. The application of phage phSE-5 and phage cocktail phSE-2/phSE-5 can be successfully employed to inactivate S. Typhimurium (reduction of 1.7 log CFU/g for phSE-5 and 0.7 log CFU/g for phSE-2/phSE-5 in artificially contaminated cockles and reduction of 0.9 log CFU/g for both in naturally contaminated cockles) during depuration in static system, especially if phSE-5 phage is used individually and if a low MOI is employed. Using conventional depuration practices in the presence of phage phSE-5, bacterial concentration is more quickly and efficiently reduced in artificially contaminated cockles. To our knowledge, this is the first report of a depuration trial using phages in the artificially and naturally contaminated cockles using industrial depuration procedures, proving that this technology can be ported into the bivalves industry. The obtained results using phages of E. coli and S. Typhimurium indicated that combining phage therapy with depuration procedures enhance bivalve microbial safety for human consumption by improving decontamination efficiency. Moreover, this approach also displays the advantage of reducing the time required for depuration and consequently its associated costs. However, the selection and characterization of appropriate phages and the most adequate multiplicity of infection to be used in phage therapy is a critical stage to achieve a successful phage-mediated control of pathogenic bacteria.

Cyanobacteria produce a variety of secondary metabolites which possess amongst others antifungal, antibacterial, and antiviral properties. Being primary producers they are also a vital component within the food web. However, certain strains also produce toxic metabolites such as the hepatotoxins microcystin (MC) and nodularin (NOD). Their toxicity in combination with the increasing global occurrence has resulted in a drinking water guideline limit of 1 μg L-1 being issued by the World Health Organisation (WHO). However, these toxins are not only present in water, but can be accumulated by fish and shellfish. Currently, no regulations regarding cyanotoxin contaminated seafood has been established despite similar toxicity to routinely monitored marine toxins such as domoic acid (DA). To facilitate regular monitoring, a high performance liquid chromatography photo diode array (HPLC-PDA) analysis method for the detection of DA was optimised to enable the simultaneous detection of DA and nine cyanotoxins. This method was then utilised to determine cyanotoxin concentration in laboratory cyanobacteria strains. To assess the accumulation and depuration of cyanotoxins in the common blue mussel Mytilus edulis, three feeding trials were performed. During these, mussels were exposed to two cyanobacteria strains, Nodularia spumigena KAC66, Microcystis aeruginosa PCC 7813, both individually and simultaneously. A rapid dose dependent accumulation of cyanotoxins was observed with maximum concentration of 3.4 -17 μg g-1 ww accumulated by M. edulis, which was followed by a much slower depuration observed. During the final feeding trial, with N. spumigena KAC 66 and M. aeruginosa PCC7813, cyanotoxins were still detectable following 27 days of depuration. Mortality in all studies was 7% or less indicating that most mussels were unaffected by the maximum dose of 480 μg L-1 NOD (feeding study 1), 390 μg L-1 MC (feeding study 2), or 130 μg L-1 total cyanotoxins (feeding trial 3), respectively. Mortality in negative control tanks was lower throughout all three feeding trials ( < 1 - 2.6%). Consumption of a typical portion size (20 mussels) would result in ingestion of cyanotoxins at levels significantly higher than the WHO recommended tolerable daily intake (TDI) of 2.4 μg NOD and/or MCs for a 60 kg adult. This value was exceeded not only during the exposure period (maximum levels 270 - 1370 μg cyanotoxins per 20 mussels), but also at the end of the depuration period 39-600 μg cyanotoxins per 20 mussels. These results illustrated that cyanotoxin monitoring of seafood should be considered not only during, but also following bloom events. In an attempt to investigate the cyanotoxin budget of the experimental system, not only mussels, but cyanobacteria cultures, the tank water, and the mussel faeces were also analysed for their cyanotoxin content. Results showed that large quantities of MCs and NOD were unaccounted for during all exposure trials. The combined effect of cyanotoxin metabolism in M. edulis, biotic and/or abiotic degradation, protein binding, and losses during the extraction and analysis were thought to have contributed to the unaccounted cyanotoxin fraction. Mussel flesh was analysed for the presence of glutathione or cysteine conjugates, however, there was no evidence of their occurrence in the samples tested. Due to these discrepancies in the toxin budget of the system, the introduction of correction factors for the analysis of cyanotoxins in M. edulis was suggested in order to protect the general public.

Norovirus (NoV) is a significant cause of gastroenteritis globally, and the consumption of oysters is frequently linked to outbreaks. Depuration is the principle means employed to reduce levels of potentially harmful agents or toxins in shellfish. The aim of this thesis is to construct mathematical models which can describe the depuration dynamics of water-borne pathogens, and specifically examine the dynamics of NoV during depuration for a population shellfish. Legislation is currently under consideration within the EU by the Directorate-General for Health and Consumers (DG SANCO) to limit the maximum level of NoV that consumers are exposed to via this route. Therefore it is important to the utility of the thesis that any models constructed should incorporate control measures which could be used to implement minimum NoV levels. Doing so allowed calculation of minimum depuration times that would be required to adhere to the control measures incorporated into the models. In addition to modelling the impact on pathogens during the depuration, we wished to gain some insight into how the variability, and not just the mean levels, of water-borne pathogens can be as important with respect to the length of depuration required to minimise any food safety risks to the consumer. This proved difficult in the absence of any data sets that can be used to calculate variability measures, as little data is currently available to inform these values for NoV. However, our modelling techniques were able to calculate an upper limit on the variability of water-borne pathogens that can be well approximated by lognormal distributions. Finally we construct a model which provided linkage between the depuration process and the accretion of pathogens by shellfish while still within farming waters. This model proposed that the pulses of untreated waste waters released by sewage treatment works due to high levels of rainfall would be transmitted into shellfish whilst filter-feeding.

Mestrado em Engenharia Alimentar - Instituto Superior de Agronomia
Manila clam (Ruditapes philippinarum), mussel (Mytilus sp.) and peppery furrow shell clam (Scrobicularia plana) are species with high abundance in the Tagus estuary. However, these species may have high levels of contaminant metals. This study aimed to determine the effect of depuration of manila clam, mussel and peppery furrow shell clam on the content of contaminant metals (Cd, Pb and Hg) and on macro, micro and trace elements (S, Ca, K, Cl, Fe, Cu, Zn, As, Se, Br, Rb and Sr). The results revealed that the depuration was effective in reducing the levels of Pb in peppery furrow shell clam and Manila clam. In the mussel no decrease was registered in this contaminant. During the depuration no decreases were registered in Hg and Cd. Mussel and peppery furrow shell clam condition decreased through the depuration, as indicated the glycogen content in the adductor muscle of these bivalves. In peppery furrow shell clam the mortality rate reached 11 %. Manila clam proved to be the most adaptive to depuration conditions. The depuration also decreased the excess of Fe in Manila clam and peppery furrow shell clam, whose levels were above the tolerable upper limit (UL). In the mussel this decrease resulted in a disadvantageous loss of this mineral

Use of antibiotics in the aquaculture industry for the control of bacterial infections in salmon has led to public concern regarding antibiotic residues in salmon tissue and the potential health risk this poses to humans. Oxytetracycline and Romet-30 are two common antibacterial agents utilized to control disease in the local finfish aquaculture industry of British Columbia, Canada. Many fish farms in British Columbia are located within close proximity to existing shellfish stocks. The potential for antibiotic bioconcentration and the production of bacterial resistance to the drugs in bivalves is a concern. The development of a solid phase extraction technique for these two drugs from Pacific oysters, Crassostrea gigas was accomplished. Analysis of whole oysters via HPLC revealed detectable levels of oxytetracycline and Romet-30 up to 4 weeks after antibiotic treatment at the salmon farm site. Oysters suspended in the salmon net pens and surrounding waters were sampled over a 5 month period. Concentration of oxytetracycline residues in oyster tissue reached a maximum of 0.11 ppm (n=2). Levels of sulphadimethoxine in oyster tissue reached a maximum concentration of 1.27 ppm (n=2). Maximum detectable concentrations of ormetoprim in oysters were 0.26 ppm (n=2). A controlled study investigating uptake and depuration of oxytetracycline and Romet-30 in the Pacific oyster revealed results similar to those described for the salmon farm. A flow through drug delivery system for the Pacific oyster was utilized over a ten day uptake and thirty day depuration period. Levels of oxytetracycline in whole animal tissue increased in a linear fashion (r²=0.984) over the uptake period. This indicates that the drug was bioaccumulated in the oyster reaching a maximum concentration of 10.72 ± 2.4 s.e. ppm (n= 3) on day 10 of uptake. Depuration of the drug was rapid. After thirteen days a concentration of 0.21 ± 0.04 s.e. ppm (n=7) was detected. The detection of Romet-30 in the uptake and depuration in the oyster was more erratic. Day 7 of uptake revealed a maximum concentration of sulphadimethoxine and ormetoprim of 1.092 ± 0.24 s.e. ppm (n=7) and 0.21 ppm (n=3) respectively. Depuration of Romet-30 was rapid. The concentration decreased to 0.029 ppm (n=3) by day 13. Condition indices of oysters sampled before and after antibiotic treatment indicated a significant increase (p<0.05) in condition index after treatment with medicated feed. A quantitative survey of bacteria associated with the gut of the oyster was performed. Relative numbers of endogenous bacteria were compared to oysters before and after antibiotic treatment. Numbers of bacteria significantly decreased (p< 0.05) following treatment.
Land and Food Systems, Faculty of
Graduate

A comprehensive method for the analysis of 11 target pharmaceuticals representing multiple therapeutic classes was developed for biological tissues (fish) and water. Water samples were extracted using solid phase extraction (SPE), while fish tissue homogenates were extracted using accelerated solvent extraction (ASE) followed by mixed-mode cation exchange SPE cleanup and analyzed by liquid chromatography tandem mass spectrometry (LC-MS/MS). Among the 11 target pharmaceuticals analyzed, trimethoprim, caffeine, sulfamethoxazole, diphenhydramine, diltiazem, carbamazepine, erythromycin and fluoxetine were consistently detected in reclaimed water. On the other hand, caffeine, diphenhydramine and carbamazepine were consistently detected in fish and surface water samples. In order to understand the uptake and depuration of pharmaceuticals as well as bioconcentration factors (BCFs) under the worst-case conditions, mosquito fish were exposed to reclaimed water under static-renewal for 7 days, followed by a 14-day depuration phase in clean water. Characterization of the exposure media revealed the presence of 26 pharmaceuticals while 5 pharmaceuticals including caffeine, diphenhydramine, diltiazem, carbamazepine, and ibuprofen were present in the organisms as early as 5 h from the start of the exposure. Liquid chromatography ultra-high resolution Orbitrap mass spectrometry was explored as a tool to identify and quantify phase II pharmaceutical metabolites in reclaimed water. The resulting data confirmed the presence of acetyl-sulfamethoxazole and sulfamethoxazole glucuronide in reclaimed water. To my knowledge, this is the first known report of sulfamethoxazole glucuronide surviving intact through wastewater treatment plants and occurring in environmental water samples. Finally, five bioaccumulative pharmaceuticals including caffeine, carbamazepine, diltiazem, diphenhydramine and ibuprofen detected in reclaimed water were investigated regarding the acute and chronic risks to aquatic organisms. The results indicated a low potential risk of carbamazepine even under the worst case exposure scenario. Given the dilution factors that affect environmental releases, the risk of exposure to carbamazepine will be even more reduced.

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico
A poluiÃÃo dos recursos hÃdricos, principalmente, decorrente do lanÃamento de esgotos domÃsticos sem tratamento ou de sistema de coleta deficitÃrio, gera graves prejuÃzos ao desenvolvimento sÃcioeconÃmico, afetando significativamente a qualidade de vida da populaÃÃo. No Brasil, a coleta e tratamento de esgoto sanitÃrio sÃo considerados precÃrios. O Plano de Gerenciamento das Ãguas da Bacia do Jaguaribe (SRH, 1999) apontou o esgoto domÃstico como uma das principais fontes poluidoras da bacia, dado que poucas cidades na bacia possuem sistema pÃblico de coleta e tratamento de esgoto. Sendo assim, pode-se afirmar, sem sombra de dÃvida, que os centros urbanos na Bacia do Jaguaribe sÃo potenciais poluidores dos seus corpos hÃdricos por esgotos domÃsticos, em virtude da nÃo existÃncia de sistema adequado de coleta, tratamento e despejo final de seus efluentes nos corpos receptores. Observa-se, portanto, a importÃncia fundamental do serviÃo ambiental prestado pelo Rio Jaguaribe e seus afluentes na diluiÃÃo e na autodepuraÃÃo das cargas orgÃnicas que a eles sÃo destinadas. A precificaÃÃo deste serviÃo ambiental induzirà os agentes econÃmicos a calcularem a relaÃÃo custo-benefÃcio, caso queiram utilizÃ-lo. Nesta pesquisa, o custo do serviÃo ambiental prestado pelo Rio Jaguaribe foi estimado pelos custos com a instalaÃÃo de estaÃÃes de tratamento de esgotos (lagoas de estabilizaÃÃo), implantadas no Estado do CearÃ, entre os anos de 2008 e 2010. Foi realizada simulaÃÃo com o modelo numÃrico QUAL2BR. O valor total do tratamento estimado para o cenÃrio atual (2010) foi de R$ 5.658.365,92. Este à o custo que, teoricamente, à fornecido, gratuitamente, pelo Rio Jaguaribe pelos serviÃos ambientais de autodepuraÃÃo e de diluiÃÃo das cargas poluidoras dos efluentes. Outra analise que se fez, foi analisar o impacto das mudanÃas climÃticas na autodepuraÃÃo do corpo hÃdrico (em termos de DBO) usando dois modelos de mudanÃa climÃtica: o HadGEM2-AO e o CanESM2.
The pollution of water resources, mainly arising from the release of untreated domestic sewage collection system or deficit, raises serious damage to the socioeconomic development, significantly affecting the quality of life. In Brazil, the collection and treatment of sewage are considered precarious. The Management Plan Basin Water Jaguaribe (SRH, 1999) pointed domestic sewage as a major pollution sources in the basin, given that few cities in the basin have public collection system and wastewater treatment. Thus, one can say without a doubt that urban centers in Jaguaribe Basin are potential polluters of their water bodies by domestic sewage, because of lack of adequate system of collection, treatment and final disposal of their effluents in receiving bodies. There are, therefore, the fundamental importance of the environmental service provided by Jaguaribe River and its tributaries dilution and self-purification of organic loads that they are intended. The pricing of this service environment will induce economic agents to calculate the cost-benefit, if they want to use it. In this research, the cost of the environmental service provided by Jaguaribe River was estimated costs for the installation of sewage treatment plants (stabilization ponds), implemented in the State of CearÃ, between the years 2008 and 2010. Simulation was performed with the numerical model QUAL2BR. The total estimated remediation costs for the current scenario (2010) was R$ 5.658.365,92. This is the cost that theoretically is provided free of charge by Jaguaribe River the environmental services of selfpurification and dilution of the pollutant effluent. Another analysis that was done, was to analyze the impact of climate change in the self-purification of the water body (in terms of BOD) using two models of climate change: the HadGEM2-AO and CanESM2.

Os estudos realizados em diversas partes do mundo sobre a utilização de pesticidas e os impactos que estes podem causar ao ambiente são uma das ações prioritárias para o desenvolvimento da agricultura, principalmente para aqueles pesticidas que são persistentes ao meio biótico e abiótico, como o inseticida heptacloro, que apesar de seu uso restrito para tratamento de madeira, ainda é muito usado no Brasil clandestinamente para outros fins. A maioria dos estudos realizados até agora sobre biomagnificação envolve o meio terrestre e uma pequena porcentagem desses é direcionada para o meio aquático e tem sido realizada em modelos de campo. O objetivo deste projeto foi determinar a CL50 96 horas para peixes a acumulação, biomagnificação e depuração do heptacloro em um modelo de sistema aquático. Como não existe nenhuma norma que defina o efeito cumulativo através dos níveis tróficos, pretendeu-se com esta pesquisa estimar a biomagnificação e depuração do heptacloro. Este estudo foi realizado em laboratório, em um modelo dividido em compartimentos individualizados, no qual somente as algas (Pseudokirchneriella subcapitata) foram submetidas por um período de 7 dias ao heptacloro, obtendo-se uma concentração final de 0,10 x 10-5µg heptacloro/µg algas, as quais posteriormente serviram de alimento para os microcrustáceos (Daphnia magna) durante 9 dias, que ao final concentraram 0,12 x 10-5 µg heptacloro/µg organismos. Por último, os peixes (Danio rerio) foram alimentados com microcrustáceos, no período de 5 dias, alcançando uma concentração final de 0,62 x 10-8 µg heptacloro/µg organismos. Nos últimos 9 dias, durante o período de depuração, os peixes foram alimentados em dias intercalados com microcrustáceos e ração sem contaminação com o produto, atingindo uma concentração final de 0,25 x 10-8 µg heptacloro/µg organismos. Nos testes realizados com esses três organismos, observou-se que a concentração ficou maior conforme o nível dentro do modelo proposto era mais alto, comprovando assim a hipótese do poder de bioacumulação, biomagnificação e depuração do heptacloro.
The studies carried out in different parts of the world about the pesticides use and the impacts that they can cause to the environment, are one of the priority actions for the agriculture development, mainly for those pesticides that are persistents in the biotic and abiotic environment, such as the heptachlor insecticide, which is still illegally used for others purposes in Brazil, although its use is limited for the wood treatment. The majority of the studies carried out until now about biomagnification involves the terrestrial environment and a small percentage of these studies are directed for the aquatic environment, and this small percentage has been carried out in field models. The aim of this project was to determine the LC50 96 hours for fish, accumulation, biomagnifications, and depuration of heptachlor in an aquatic system model and, as there isn?t any norm that defines the cumulative effect through trophic levels, it was claimed with this research to esteem the heptachlor biomagnification and depuration. This study was carried out in a laboratory, in a model divided in single chambers, in which the algae (Pseudokirchneriella subcapitata were submitted during 7 days to the heptaclhor, getting a final concentration of 0.10 x 10-5µg heptaclhor/µg algae, which was later served as food for the microcrustaceans (Daphnia magna) were submitted during 7 days to the heptaclhor, getting a final concentration of 0.10 x 10-5Mµg heptaclhor/µg algae, which was later served as food for the microcrustaceans (Daphnia magna) were fed with microcrustaceans, in the period of 5 days, reaching a final concentration of 0.62 x 10-8 µg heptaclhor/µg organisms. In the last 9 days, during the period of depuration, the fish were fed in days intercalated with microcrustaceans and ration without contamination with the product, reaching a final concentration of 0.25 x 10-8 µg heptacloro/µg organisms. In tests carried out with these three organisms, it was observed that the concentration was bigger as higher the level inside of the considered model, thus proving the hypothesis of the bioaccumulation, biomagnification, and depuration power of heptachlor.

O sistema óptico baseado em Visão Computacional, consiste em dispositivos de geração, aquisição e processamento das imagens da incidência de um feixe laser sobre a superfície de um escoamento e reflexão sobre uma tela horizontal. Com função de medição da turbulência na superfície do fluxo, os dispositivos de geração e aquisição de imagens foram condicionados sobre um tanque de produção hidrodinâmica de turbulência, acionado por grades oscilantes. Um software, com interface gráfica, foi desenvolvido para processamento das imagens e obtenção de dados geométricos do escoamento. Com até 30 quadros por segundo é possível visualizar a oscilação turbulenta e também as superfícies 3D, equivalentes ao escoamento real, geradas numa malha de diferenças finitas. Obtêm-se velocidades verticais, ampliações superficiais e velocidades angulares, entre outros parâmetros, em diversas situações de turbulência. No mesmo tanque foram procedidas, previamente, medidas de concentração de oxigênio dissolvido segundo uma técnica que permite determinar o coeficiente de reaeração K2. Em modelo gráfico foram reunidos dados de turbulência e coeficientes K2 de forma a possibilitar a previsão desse coeficiente em escoamentos naturais, com aplicação na estimativa da capacidade de autodepuração nos corpos d\'água receptores de efluentes, que sofrem rebaixamento do nível de oxigênio.
The optical system based on machine vision consists on generation, acquisition and processing devices of the images of a laser beam incidence on a flow surface and reflection on a horizontal screen. To measure the turbulence in the surface flow, the generation and acquisition of images devices were conditioned on a tank of hydrodynamic turbulence production by oscillating grids. Software, with graphic interface, was developed for processing the images and obtaining geometric data of the flow. With up to 30 pictures per second it is possible to visualize the turbulent oscillation and also the 3D surfaces, equivalent to the real flow, generated in a mesh of finite differences. Vertical velocities, surface enlargements and angular velocities are obtained, among other parameters, in several turbulence situations. In the same tank were proceeded, previously, measures of concentration of dissolved oxygen according to a technique that allows to determine the reaeration coefficient K2. Turbulence data and coefficients K2 were gathered in a graphic model to make possible the forecast of this coefficient in natural flows, with application on the estimation of the natural depuration capability in the receiving water bodies of inflows, that suffer lowering of the oxygen level.

The goal of the thesis is to evaluate the performance of the biochar produced by a novel pyrolysis-with-post-reforming technique (TCR), as a filtering material for wastewater, and to make a comparison with other filter materials currently on the market. Caviro winery was chosen as a case study, providing two samples of wastewater produced in their plants. Vineyard pruning was used as the feedstock for the production of biochar. Two different types of biochar were produced, which differ in the temperature at which the post-reformer was set during production (500°C and 700°C). For the two biochars and the two wastewater samples several analyses were conducted, aimed at their chemical and physical characterization. Biochar and wastewater samples have been used for sorption tests of COD and other elements contained in the wastewater, with contact times of 0.5, 2, 6, and 24 hours. The resulting waters were then re-characterized. The performance of the two biochars as filtering materials were compared with materials currently marketed for this purpose, like active carbon and commercial zeolite. An economic analysis has been performed which shows that the filtering of wastewaters with the biochar produced at the highest temperature is much less expensive than the current filtering materials and also with respect to the cost of standard processing by waste management companies in the Emilia-Romagna region (Italy).

This thesis focussed on the effects of a range of trace metals on various stages of Haliotis rubra development. The trace metals assessed in this thesis were the essential metals Cu, Zn and Fe; and, the non-essential metals Hg, Cd and Pb. Copper and Hg proved to be the two most toxic metals to the life stages of H. rubra studied. The concentrations affecting normal development of the fertilised egg exposed for 48h showed a decreasing order of toxicity with 48hEC50 recorded at 7µg Cu/L, 20µg Hg/L, 42µg Zn/L, 4,102µg Fe/L, 4,515µg Cd/L, and 5,111µg Pb/L. Settlement and metamorphosis occur in normal larvae when aged 5 days, and exposure of the 5 day old larvae to the metals for 48h resulted in impaired crawling success at 128µg/L Cu and Hg, and 1250µg Cd/L. Settlement was inhibited after exposure to 128µg Cu/L, 32µg Hg/L, and 1250 Cd/L. Metamorphosis of larvae 96h after exposure was inhibited by 32µg Cu/L, 512µg Zn/L, 32µg Hg/L and 625µg Cd/L. The rate of meta morphosis was enhanced after exposure to Cu and Hg at 0.5µg/L and 64 - 256µg Zn/L. Exposure to Zn at concentrations 64, 128 and 256 µg Zn/L caused an increased rate of settlement and metamorphosis. Juvenile H. rubra exposed to the six metals for 96h were most sensitive to Cu, which produced a 96hLC50 of 87µg Cu/L compared to Hg with a 96hLC50 of 173µg Hg/L. Juvenile H. rubra were relatively insensitive to Zn and Cd with the 96h LC50 of 1730µg Zn/L and 3700µg Cd/L, respectively. Exposure to individual solutions of Cu, Zn, and Cd for 28 days resulted in juvenile H. rubra bioaccumulating significant concentrations of metals in the visceramantleedible foot muscle. Accumulation of Hg was greater in the mantle-viscera-edible foot muscle. Following exposure, depuration in clean seawater for 28 days produced varying decreases in metal concentrations for each tissue compartment. Sodium-potassium activated ATPase (Na+,K+-ATPase) activity in the gills of juvenile H. rubra was significantly affected following expos ure to the trace metals for 28 days, with a decreasing order of effect on enzyme activity of Hg-Cu-Cd-Zn. Depuration of H. rubra in clean seawater for 28 days resulted in the recovery of Na+,K+-ATPase activity to varying degrees. The recovery of ATPase activity was more efficient following exposure to Cd-Zn-Cu-Hg. The overall results of this thesis provide initial baseline information to evaluate the sensitivity of H. rubra to trace metal toxicants, and these results may be utilised by regulators for establishing marine water quality guidelines to protect H. rubra and other abalone species in their natural habitats.

La sepsis, es una enfermedad muy grave con una alta incidencia y mortalidad a pesar de los diferentes tratamientos propuestos y sobre todo en su forma más grave, el shock séptico. La lesión renal aguda (acute kidney injury, AKI) aparece frecuentemente en el shock séptico y se asocia con un aumento de mortalidad. En los últimos años, diversos tratamientos basados en la depuración extracorpórea se han propuesto con el objetivo de mejorar la supervivencia en los pacientes sépticos con AKI. El objetivo principal de esta tesis es analizar el impacto sobre la supervivencia, de las terapias de depuración extracorpórea (TDEC), en el paciente crítico con sepsis, con especial interés en las diferentes modalidades aplicadas. Para conseguir este objetivo este trabajo de tesis se compone de dos estudios principales, el primero evalúa la incidencia y factores de riesgo de los pacientes críticos con AKI que precisan TDEC así como su evolución y pronóstico. Este estudio es un estudio observacional que incluyó 304 pacientes críticos que precisaron TDEC, de los cuales más del 60% eran pacientes sépticos. El estudio realizado durante diez años, comparó dos periodos de tiempo, el periodo inicial de cinco años versus el periodo reciente (el resto de años). Se registraron variables epidemiológicas, de gravedad, tipo y duración de la TDEC, mortalidad y recuperación de la función renal. Mediante este estudio hemos podido observar que la mortalidad de los pacientes ha mejorado durante los últimos años, que las técnicas continuas se asociaron a mayor mortalidad, pero con una mejor recuperación de la función renal en los pacientes supervivientes y que la mayoría de los pacientes recibió una técnica convectiva. El segundo estudio analizó el tratamiento con hemoperfusión con polimixina B y su efecto a nivel clínico, analítico y biológico. Este estudio es un estudio de casos y controles en el que se compararon dos cohortes de pacientes, pacientes sépticos con AKI que precisan TDEC y que además se les añadió hemoperfusión con polimixina B versus un grupo control similar a los que no se les aplica dicho tratamiento. El estudio mostró que el tratamiento con hemoperfusión con polimixina B disminuye los niveles de endotoxina circulante, pero ello no comportó una mejora a nivel clínico, analítico o biológico. Por ello, nuestras conclusiones de este trabajo de tesis son que la evolución en los últimos años ha implicado una mejora en la supervivencia de los pacientes críticos sépticos que precisaron TDEC probablemente secundario a las mejoras realizadas por las guías de la Surviving Sepsis Campaign (SSC) y que la hemoperfusión con polimixina B no debe ser un tratamiento estándar en los pacientes críticos sépticos dada su falta de evidencia científica. Se precisan mayor número de estudios randomizados para determinar la eficacia de las diferentes técnicas de “purificación sanguínea” en el paciente crítico séptico, por lo que, de momento, no deberían ser usadas de forma rutinaria en todos los pacientes.
Sepsis is a severe disease with a high incidence and mortality despite the different treatments and especially in its most severe form, septic shock. Acute kidney injury (AKI) is frequently associated with septic shock and an increase in mortality. In recent years, several extracorporeal treatments (CRRT) have been proposed with the aim of improving survival in septic patients with AKI. The main objective of this thesis is to analyze the impact on survival, of the CRRT in the critical patient with sepsis, with special interest in the different modalities applied. In order to achieve this objective, this thesis is composed of two studies. The first study, assesses the incidence and risk factors of critical ill patients with AKI that require CRRT as well as its evolution and prognosis. This study is an observational study that included 304 critical patients who required CRRT, of which more than 60% were septic patients. The study conducted over ten years, compared two periods of time, the initial period of five years versus the recent period (the rest of years). Epidemiological variables were recorded, severity of disease, type and duration of CRRT, mortality and recovery of renal function. The results show that the mortality of these patients has improved over the years, the continuous techniques are associated with higher mortality but better recovery of renal function in the survival patients and that the patients mainly performed convective technique. The second study analyzed the treatment with hemoperfusion with polymyxin B and its effect at a clinical, analytical and biological level. This is a case-control study in which two patient cohorts were compared, septic patients with AKI who required CRRT and who also received hemoperfusion with polymyxin B versus a similar control group, who did not receive the hemoperfusion treatment. The study showed that the treatment with hemoperfusion with polymyxin B decreases the levels of circulating endotoxin, but we observed no improvements in clinical, physiological or biological parameters. Therefore, our conclusions from this thesis are that the evolution in recent years has involved an improvement in the survival of critical septic patients who required CRRT probably secondary to the improvements made by the SSC guidelines and hemoperfusion with polymyxin B should not be a standard treatment in critical septic patients given its lack of evidence. A greater number of prospective, randomized trials are needed to determine the efficacy of the different techniques of "blood purification" in critical septic patients, meanwhile they should not be used routinely in all patients.

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The development of human activities generates high amounts of industrial effluent, which has a high impact on watercourses, mainly due to organic load constituents. Among the methods used to control water pollution, the method of mathematical modeling stands out, a simulation tool that allows the generation of future scenarios. This study proposes to generate a mathematical model of water quality that simulates the process of aerobic self-depuration of organic matter from watercourses. For this purpose, it was used a water bath coupled to a jar test, providing temperature control from 20 to 28 °C, and flow velocity from 0.29 to 0.87 m s-1, similarly to natural conditions. The trials were conducted using a synthetic effluent with an initial COD concentration of 50 mg L-1, based on a Central Composite Design (DCC), composed of seven trials. All trials lasted 15 days, with effluent samples collected daily for the analysis of Chemical Oxygen Demand (COD) and Dissolved Oxygen (OD). A mathematical equation was developed for each day of self-depuration. The final mathematical model gathers 15 equations of self-depuration. The significance of the equations was measured using the analysis of variance to 10%. To validate the proposed model, a self-depuration trial was carried out under the conditions of 26 °C and 0.38 m s-1 with an initial COD concentration of 30 mg L-1. The analysis of variance was performed for the proposed mathematical model as well as the analysis of normality and homoscedasticity for waste, with a significance level of 5%.There are indications that the temperature significantly had an influence in the kinetics of aerobic decomposition of organic matter in the first and from the sixth to the fifteenth day self-depuration. The flow velocity significantly influenced in the eighth and from the twelfth to the fifteenth day of self-depuration, and the interaction between the factors in the eighth and fifteenth day of self-depuration, with p-values lower than the significance level adopted. With a confidence interval of 90%, the equations representing the first and from the seventh to the fifteenth day of self-depuration are statistically significant, with coefficients of determination (R2) greater than 84%. The proposed model adequately described the experimental data obtained in the validation trial, presented p-value of 2.49 E-17, lower than the level of significance adopted, of 5%. Thus, the model proposed can be considered statistically significant, describing the total variation of responses, with a ratio of 99.46%. The proposed mathematical model described the process of self-depuration in watercourses within the temperature and flow velocity intervals in which it was generated
O desenvolvimento das atividades humanas teve como consequência direta a geração de elevada quantidade de efluentes industriais, altamente impactantes aos cursos hídricos receptores, devido principalmente à carga orgânica constituinte. Dentre os métodos utilizados para o controle da poluição hídrica, destaca-se a modelagem matemática, a qual, sendo uma ferramenta de simulação, possibilita a geração de cenários futuros. O presente estudo propõe a geração de um modelo matemático de qualidade da água que possibilite simular o processo de autodepuração aeróbia da matéria orgânica de um corpo hídrico. Para a realização do estudo utilizou-se um banho-maria acoplado a um jar test, possibilitando o controle da temperatura na faixa de 20 a 28 °C e velocidade de fluxo na faixa de 0,29 a 0,87 m s-1, valores típicos encontrados em condições naturais. Os ensaios foram conduzidos utilizando-se efluente sintético a partir de uma concentração inicial de DQO de 50 mg L-1, com base em um Delineamento Composto Central (DCC), composto por 7 ensaios. Todos os ensaios tiveram duração de 15 dias, com coletas diárias de amostras de efluente para análise de Demanda Química de Oxigênio (DQO) e Oxigênio Dissolvido (OD). Gerou-se uma equação matemática para cada dia de autodepuração. O modelo matemático final reúne 15 equações de autodepuração. A significância das equações foi avaliada utilizando-se a Análise de Variância a 10%. Realizou-se a validação do modelo proposto, com base em um ensaio de autodepuração conduzido nas condições de 26 °C e 0,38 m s-1 a partir de uma concentração inicial de DQO de 30 mg L-1. Realizou-se a análise de variância para o modelo matemático proposto, assim como análise de normalidade e homoscedasticidade para os resíduos, com um nível de significância de 5%. Há indícios de que a temperatura influenciou significativamente na cinética de decomposição aeróbia da matéria orgânica no primeiro e do sexto ao décimo quinto dia autodepuração. A velocidade de fluxo influenciou significativamente no oitavo e do décimo segundo ao décimo quinto dia de autodepuração e a interação entre os fatores, no oitavo e no décimo quinto dia de autodepuração, apresentando p-valores menores que o nível de significância adotado. Com um intervalo de confiança de 90%, as equações representativas do primeiro e do sétimo ao décimo quinto dia de autodepuração, são estatisticamente significativas, apresentando coeficientes de determinação (R2) superiores a 84%. O modelo proposto descreveu satisfatoriamente os dados experimentais obtidos no ensaio de validação, apresentado p-valor de 2,49E-17, menor que o nível de significância adotado, de 5%. Assim, considera-se o modelo proposto como sendo estatisticamente significativo, descrevendo a variação total das respostas, com uma proporção de 99,46%. O modelo matemático proposto descreve satisfatoriamente o processo natural de autodepuração em cursos hídricos, dentro dos limites de temperatura e velocidade de fluxo em que foi gerado

Atualmente, as perdas econômicas são uma realidade devido ao problema de off flavor em pescado, ocasionados pela qualidade da água dos criatórios e pelo manejo empregado no cultivo, nem sempre satisfatórios. Buscou-se a avaliação microbiológica, físico-química e sensorial dos peixes, com a finalidade de detectar prováveis alterações que estivessem comprometendo a qualidade do pescado. Com o objetivo de detectar e controlar o off flavor em tilápias cultivadas foi sugerido a depuração antes da distribuição e venda e a utilização da defumação como meio de mascarar este problema. O monitoramento da qualidade do pescado iniciou-se com as análises microbiológicas, físico-químicas e biológica da água dos tanques de cultivo e de depuração. Os peixes provenientes de área de cultivo do Estado de São Paulo, região de Artur Nogueira, da espécie tilápia do Nilo, Oreochromis niloticus, foram submetidos à depuração (3, 5 e 7 dias) e a seguir foram eviscerados e filetados. Os peixes submetidos à depuração e o controle foram comparados entre si para posterior escolha do melhor tempo para depuração; estes, não apresentaram diferenças significativas (p>0,05) para composição centesimal, nitrogênio não protéico - NNP, bases nitrogenadas voláteis totais - BNVT e pH nos tempos de depuração. O processo de depuração provocou perda de peso mais intensa nos três primeiros dias de depuração. Através das análises sensoriais verificou-se que os peixes, que corresponderam ao controle, apresentaram maior intensidade de off flavor quando comparados aos demais. A depuração por 3 dias para o atributo odor apresentou eficiência semelhante, estatisticamente (Teste F), ao tratamento por 5 dias porém, foi considerada diferente do tratamento por 7 dias. Para o atributo sabor os tratamentos de 3, 5 e 7 dias não diferiram, estatisticamente, entre si. A água do tanque de cultivo apresentou problemas de eutrofização e presença de geosmina, ao contrário da água do tanque de depuração que apresentou-se límpida e ausente de geosmina. Os peixes que não sofreram depuração (controle), foram submetidos à defumação. Os filés de peixe in natura e os defumados foram comparados entre si, quanto a composição centesimal e verificou-se que estes foram afetados significativamente (Teste F). Para o nitrogênio não protéico - NNP, as bases nitrogenadas voláteis totais - BNVT e o pH não houve alteração significativa (p>0,05) quanto aos tratamentos. Através das análises sensoriais verificou-se que os peixes in natura apresentaram maior intensidade de off flavor quando comparados aos defumados. Para os atributos odor e sabor houve diferença significativa (p>0,05) entre os tratamentos. O processo de depuração permitiu bons resultados quanto a eliminação de off flavor da tilápia, pois, através das análises realizadas, pode-se aferir o tempo ideal de 5 dias de depuração conduzida em um tanque com água corrente e limpa. Quando se comparou o pescado defumado com o pescado in natura, o primeiro recebeu uma maior aceitação pelos degustadores. O processo de defumação é uma forma de mascarar a presença do off flavor; é um processo simples, pouco oneroso e que pode ser adotado prontamente pelos produtores como forma de agregar valor ao pescado.
Currently, economic losses are a reality due to the fish off flavor provoked by the handling used in the culture and by the water quality of the fish tanks, which are not always satisfactory. Microbiological, physical-chemical and sensory evaluations of the fish were carried out in order to detect probable alterations that would compromise the fish quality. The off flavor detection, as well as, the suggestion for depuration before distribution and sale, and the use of the smoking as a way of disguising this problem were the objectives of this research. Microbiological, physical-chemical and biological analyses of the waters in the fish and the depuration ponds were performed to monitor the quality of the fish. The fish– Nile Tilapias (Oreochromis niloticus) from the area of Arthur Nogueira, in the State of São Paulo – was submitted to the depuration (3, 5 and 7 days). The fish submitted to the depuration and the control fish were compared in order to find the best depuration period. No significant differences (p>0.05) for centesimal composition, non-protein nitrogen - NNP, total base volatile nitrogen BNVT, and pH were found among the depuration periods. The depuration process provoked a more intense weight loss in the first three days for depuration. Through the sensory analyses, we could verify that the control fish presented a greater off flavor intensity than the others. The three-day depuration showed a similar statistical efficiency (F Test) than that of the five-day treatment, but differed from that of the 7-day treatment. As for the flavor attribute, the 3, 5, and 7-day treatments did not show a significant difference, statistically. The water in the fish pond presented eutrophization problems and presence of geosmine, whereas the water in the depuration pond was clear and geosmine-free. The fish that did not go through depuration (control) were submitted to smoking. Fresh fish fillets were compared to the smoked ones. As to the centesimal composition, we verified that they were significantly affected (F Test). As to non-protein nitrogen – NNP, total base volatile nitrogen – BNVT and pH, there were no significant changes (p>0.05) either among the treatments. Through sensory analysis, we verified that the fresh fish presented a more intense off flavor than the smoked ones. As to odor and flavor, there was a significant (p>0.05) difference among the treatments. The depuration process was efficient in the elimination of the off-flavor in the tilapia, for, according to our analyses, we could conclude that the ideal period for this elimination was 5 days of depuration, carried out in a pond with clean running water. When compared to the fresh fish, the smoked fish was better accepted by the panelists. The smoking process is a way of disguising the off flavor; it is a simple, inexpensive process, which can be readily adopted by producers a way of adding value to the fish.

La tesi estudia la repressió a la universitat espanyola duta a terme pel règim encapçalat pel general Francisco Franco. Primer s'analitzen els esforços republicans per consolidar la democràcia a partir de l'educació, amb l'oposició de l'Església catòlica i les classes conservadores que veuen perillar el seu control i privilegis. La guerra civil converteix la violència verbal en física i es desencadena una contundent repressió que en el cas del funcionariat -i el professorat particularment es disfressa com a depuració professional. El mèrit acadèmic dóna pas al mèrit polític i s'inicia una purga política contra tot docent sospitós o no prou compromès. A diferència de la depuració republicana defensiva i respectuosa amb la legalitat, la franquista escapça l'escalafó amb contundents i generalitzades sancions -assassinats, cessaments, empresonaments, trasllats, inhabilitacions i jubilacions forçoses . A més, la ciència queda sotmesa a la ideologia nacional-catòlica i les vacants esdevenen botí de guerra pels addictes.
This work studies the repression suffered by the Spanish university during the first years of Franco's dictatorship. First of all, the efforts of the Republican government to consolidate the democracy from the bases of the education are analyzed, together with the opposition exerted by both the Spanish Catholic Church and the conservative class, who feared about the loss of power and privileges. The civil war transforms the oral violence into physical violence and triggers the burst of a fierce repression, which in the particular case of teachers, is dressed-up as a professional depuration. Political merits and a political purge against any suspicious professor -or even against professors that are not enough engaged with the new regimen substitute the excellence in the academic records. Contrary to the republican depuration, which was defensive and respectful with the legacy effective, the Francoist depuration beheads the university roster with general and merciless punishments -murders, dismisses, imprisonments, transfers and forced retirements . Moreover, science starts to be ruled by the national-catholic ideology and the available positions become booty for those who prove to be followers of the new regimen.

Fundação de Amparo a Pesquisa do Estado de Minas Gerais
This study evaluated the capacity of self-depuration of the Jordão River considering the true contributions of the Brejo Alegre stream in time of drought and during the rainy period, having in sight the launching of effluents of part of Araguari town, Minas Gerais, in the stream using QUAL-UFMG model. There was the simulation of two situations, considering estimated pollutant loads of Sewage Treatment Plants and the low capacity of dilution of the river for the critical flow, using anaerobic lake treatment system followed by facultative lake (1st Situation) and by conventional activated sludge (2nd Situation), launched directly at the confluence of Brejo Alegre stream and Jordão River. Parallel to the study of self-depuration it was determined the key-curve in a specific point of the Jordão River, beyond the Water Quality Index in the Brejo Alegre stream right at the confluence with the Jordão River, and along the Jordão River, for the periods of drought and rain. In the tracing of the key-curve, the data measured adjusted well to the estimated ones of flow, reaching the equation Q = 9.804.(h+0.7)3.672, attributing the Coefficient of Determination to equal to 0.815 until the absence of rotation counter of the reel s helices in the beginning of the experimental activities. The study of Water Quality Index for the period of drought detected a good level for the Jordão River at all points, coinciding with the level encountered in the 2nd trimester of 2010, in according to the Instituto Mineiro de Gestão de Águas monitoring, resulting Water Quality Index equal to 66.92, 87.90, 86.73, 87.79 and 87.97, respectively, for the Brejo Alegre stream, points A, B, C and D of the Jordão River, from upstream to downstream. Yet in the rainy period it achieved medium level of Water Quality Index for the Brejo Alegre stream and point A of the Jordão River upstream from the confluence of the stream and a good level for the Jordão River downstream from the confluence, being equal to 57.77, 52.59, 86.29 and 77.73, respectively, for the Brejo Alegre stream, points A, B and D of the Jordão River, from upstream to downstream. The simulations for the drought period and rainy period presented satisfactory adjusts to the data measured to the estimated, showing the prevalence of the deoxygenating by carbonaceous demand over the nitrification and the importance of the natural repair in the self-depurating process. The dissolved oxygen, nitrogen and fractions, phosphorus and fecal coliform (Escherichia-coli in this study) parameters respected the limits recommended by the Conselho Nacional do Meio Ambiente, Resolution 357:2005, in all its extension, for the Class 2 rivers, classification in which the Jordão River fits. In regard to biochemical oxygen demand, the whole section is out of the regulation due to the reception of pollutant loads from the Brejo Alegre stream. As for the simulating of extreme situations, a pollution estimated for 7422 habitants for the 1st Situation and 14840 habitants for the 2nd Situation would guarantee the capacity of self-depuration of the Jordão River, respecting the recommendations of the Resolution 357:2005, considering the imprecision of the methodology of analysis of the biochemical oxygen demand and that in the simulations it was used a critical flow of the Jordão River 2.6 times inferior to the smallest flow measured in the period of drought.
Este trabalho avaliou a capacidade de autodepuração do rio Jordão considerando-se as contribuições reais do córrego Brejo Alegre em período de estiagem e chuvoso, tendo em vista o lançamento de efluentes brutos de parte da cidade de Araguari, Minas Gerais, no córrego, utilizando o modelo QUAL-UFMG. Também simulou-se dois cenários, considerando cargas poluidoras estimadas de Estações de Tratamento de Esgoto e a baixa capacidade de diluição do rio para a vazão crítica, utilizando sistema de tratamento por lagoa anaeróbia seguida por lagoa facultativa (1º Cenário) e por lodo ativado convencional (2º Cenário), lançadas diretamente na confluência do córrego Brejo Alegre com o rio Jordão. Paralelo ao estudo de autodepuração foi determinada a curva-chave em um ponto específico do rio Jordão, além do Índice de Qualidade das Águas no córrego Brejo Alegre logo na confluência com o rio Jordão, e ao longo do rio Jordão, para os períodos de estiagem e chuvoso. No traçado da curva-chave, os dados medidos ajustaram-se bem aos estimados de vazão, alcançando a equação Q = 9,804.(h+0,7)3,672, atribuindo o Coeficiente de Determinação igual a 0,815 à ausência de contador de rotações da hélice do molinete no início das atividades experimentais. O estudo do Índice de Qualidade das Águas para o período de estiagem detectou nível bom para o rio Jordão em todos os pontos, coincidindo com o nível encontrado no 2º trimestre de 2010, de acordo com o monitoramento do Instituto Mineiro de Gestão das Águas, resultando Índice de Qualidade das Águas igual a 66,92, 87,90, 86,73, 87,79 e 87,97, respectivamente, para o córrego Brejo Alegre, pontos A, B, C e D do rio Jordão, de montante a jusante. Já no período chuvoso alcançou-se nível médio do Índice de Qualidade das Águas para o córrego Brejo Alegre e ponto A no rio Jordão a montante da confluência com o córrego e nível bom para o rio Jordão a jusante da confluência, sendo igual a 57,77, 52,59, 86,29 e 77,73, respectivamente, para o córrego Brejo Alegre, pontos A, B e D do rio Jordão, de montante a jusante. As simulações para o período de estiagem e chuvoso apresentaram satisfatórios ajustes dos dados medidos aos estimados, evidenciando a prevalência da desoxigenação por demanda carbonácea sobre a nitrificação e a importância da reaeração natural no processo de autodepuração. Os parâmetros oxigênio dissolvido, nitrogênio e frações, fósforo e coliformes termotolerantes (Escherichia-coli neste trabalho) respeitaram os limites preconizados pelo Conselho Nacional do Meio Ambiente, Resolução 357:2005, em toda a sua extensão, para rios de Classe 2, classificação em que o rio Jordão enquadra-se. Com relação a demanda bioquímica de oxigênio, todo o trecho encontrou-se fora da regulamentação devido ao recebimento de cargas poluidoras do córrego Brejo Alegre. Quanto à simulação dos cenários extremos, uma população estimada de 7422 habitantes para o 1o Cenário e 14840 habitantes para o 2º Cenário garantiriam a capacidade de autodepuração do rio Jordão, respeitando as preconizações da Resolução 357:2005, considerando-se as imprecisões da metodologia de análise da demanda bioquímica de oxigênio e que nas simulações adotou-se uma vazão crítica no rio Jordão 2,6 vezes inferior à menor vazão medida no período de estiagem.
Mestre em Engenharia Civil

Field observations were made at Loch Sween in an attempt to describe the behaviour and ecology of L.depurator. Abundance varied over time with peak abundance occurring during periods of warm water. Peak densities of 1 crab/7m [sq] were observed but average density was much lower at 1 crab 25m [sq]. Some evidence was obtained for migration from the study site similar to that reported for other species. Tagging studies revealed no long term site attachment. Populations were found to be sex biased in favour of male during summer months and individuals were most commonly observed within 1m of the nearest conspecific. Ovigerous crabs were observed in two distinct phases between April and September and recruitment of juvenile crabs; occured in early spring. Observations on food and feeding behaviour showed L depurator to be a predator of sessile or slow moving benthic macroinvertebrates. The main types of escape response were observed and discussed. The incidence of physical damage and naturally occurring aggression in the field were low. Investigation into the locomotor activity of individual swimming crabs in the laboratory showed that shallow water (<9m) crabs displayed significant cyclic locomotor activity while deep water (>30m) crabs displayed arhythmic activity.

L’attuale condizione che caratterizza il settore energetico richiede un necessario processo di riconversione che, oltre a favorire il risparmio energetico, riduca la dipendenza dai combustibili fossili ed accresca l’impiego di fonti energetiche rinnovabili, dando un contributo fondamentale alla riduzione delle emissioni di gas serra come diversi accordi internazionali richiedono. Si rende pertanto necessario accelerare i processi che da alcuni anni stanno favorendo l’utilizzo di energia da fonti rinnovabili. Tra queste, le fonti legate ai processi di trattamento biologico dei reflui stanno avendo un interessante sviluppo. Esistono numerosi processi biologici che consentono la produzione di energia in maniera indiretta, quali ad esempio i processi di digestione anaerobica finalizzati alla produzione di biogas e/o produzione biologica di idrogeno. In tale contesto si inserisce la tecnologia delle Microbial Fuel Cell, che consente la produzione diretta di energia elettrica, finalizzata al recupero energetico inteso al miglioramento dell’efficienza energetica e alla riduzione dei costi d’esercizio di impianti di trattamento biologico dei reflui. Il presente lavoro di Tesi di Dottorato sperimentale, svoltosi in collaborazione al laboratorio PROT.-IDR. della sede ENEA di Bologna, riporta i risultati dell’attività di ricerca condotta su una MFC (Microbial Fuel Cell) a doppio stadio biologico per il trattamento di reflui ad elevato carico organico e produzione continua di energia elettrica. E’ stata provata l’applicabilità della MFC con entrambi i comparti biotici utilizzando elettrodi di grafite non trattata ottenendo, con un carico organico in ingresso di circa 9 gd-1, valori di potenza massima prodotta che si attestano su 74 mWm-2, corrente elettrica massima generata di 175 mAm-2 ad una tensione di 421 mV, ed una conversione di COD in elettricità pari a 1,2 gCODm-2d-1. I risultati sono stati molto positivi per quanto riguarda le prestazioni depurative ottenute dalla MFC. L’efficienza di depurazione misurata ha raggiunto un valore massimo del 98% di rimozione del COD in ingresso, mentre e la concentrazione di azoto ammoniacale nell’effluente raccolto all’uscita del sedimentatore è sempre stata inferiore a 1 mgN-NH4+l-1. Tra gli obiettivi posti all’inizio della sperimentazione si è rivelata di notevole interesse la valutazione del possibile utilizzo della MFC come sistema per il monitoraggio on-line del COD e degli acidi grassi volatili (VFA) prodotti all’interno di un digestore anaerobico, attraverso la definizione di una correlazione tra i dati elettrici registrati in continuo e le concentrazioni di CODanaer e VFA misurate in diversi periodi della sperimentazione. L’analisi DGGE della biomassa catodica ha fornito uno strumento analitico utile allo studio della diversità della comunità microbica sospesa ed adesa al catodo e ha confermato la forte similarità delle specie batteriche riconosciute nei campioni analizzati. In particolare, le bande di sequenziamento ottenute sono affiliate ai gruppi batterici Firmicutes, -Proteobacteria,  -Proteobacteria, -Proteobacteria e Bacteroidetes. Da quanto emerso dalla sperimentazione condotta si può pertanto concludere che ad oggi le MFC sono in fase di evoluzione rispetto ai primi prototipi utilizzati per lo studio delle comunità microbiali e per la comprensione dei meccanismi di trasferimento elettronico. Sfruttarne la potenza prodotta in maniera commerciale diviene una grande sfida per il futuro, ed è opinione comune che le prime applicazioni pratiche delle MFC saranno come fonte di recupero energetico per i dispositivi utilizzati per il monitoraggio dell’ambiente e per il trattamento delle acque reflue.

Lo studio si inserisce in un progetto più ampio per lo sviluppo di una pesca sostenibile, condotto dai ricercatori di CESTHA, Centro Sperimentale per la Tutela degli Habitat, nella marineria ravennate. Il lavoro ha previsto raccolta dati e successiva elaborazione su due tecniche sperimentali di pesca. La prima consta nell’uso di nasse rigide per la pesca di S. mantis, ed è stata analizzata e confrontata con la tecnica tradizionale delle reti da posta: in termini di qualità e quantità del pescato (commerciale e non commerciale) ed in termini di guadagno economico. Il risultato è una differenza sostanziale nella selettività e nella capacità di cattura dei due strumenti, a favore della tecnica sperimentale. Questo, aggiunto ai minori tempi di lavoro richiesti dal primo attrezzo e ad un guadagno finale nettamente superiore, fa sì che i vantaggi siano notevoli e molteplici e che quindi la tecnica a nasse per la pesca di S. mantis possa essere un’alternativa valida e sostenibile sia dal punto di vista ambientale che da quello economico. Ciononostante, proprio a causa dell’altissima selettività rivolta alla specie target, la pesca con questo strumento necessita di ulteriore monitoraggio e rigida regolamentazione per poter risultare effettivamente sostenibile. La seconda tecnica analizzata ha previsto la sperimentazione di uno strumento innovativo per la cattura di esemplari adulti di L. depurator, abbinata alla selezione manuale dei soli maschi. Essendo un sistema totalmente nuovo, lo scopo è stato verificare l’effettiva capacità di cattura nei confronti della specie target. Durante il periodo di raccolta dati sono emerse alcune criticità proprie del nuovo attrezzo che hanno portato a risultati non del tutto positivi in termini di quantitativi di pescato, seppur con un livello qualitativo eccellente. Anche l’impatto sul by catch è risultato minimo, ma risulta necessario proseguire la sperimentazione con modifiche funzionali per rendere lo strumento efficiente.

Thesis (Ph.D.) -- University of Glasgow, 2008.
Ph.D. thesis submitted to the Division of Environmental and Evolutionary Biology, Institute of Biomedical and Life Sciences, University of Glasgow, 2008. Includes bibliographical references. Print version also available.

Tese de doutoramento, Biologia (Biologia Marinha e Aquacultuta), Universidade de Lisboa, Faculdade de Ciências, 2014
Bivalves are extremely important in Portuguese economy and gastronomy, being clams the main species consumed. Nevertheless, bivalve consumption raises specific food safety concerns, particularly due to the accumulation of biological contaminants, including microbial and chemical, as they are filter‐feeders inhabiting estuaries constantly subjected to contamination and climate variability. In this context, the main objectives of this dissertation were to investigate the bivalve consumption behaviour, to compare the microbiological, chemical and physiological responses of native and invasive clams to depuration and transport in semi‐dry conditions at optimal and stressful temperatures, and to assess the impact of warming in bivalve metabolism, oxidative stress and nutritional quality. Bivalve consumer's presented risky behaviours that differed according to their demographic and socio‐economic characteristics. Higher bacterial levels were observed in invasive species, regardless of season and environmental parameters (higher Escherichia coli and total viable counts in winter and Vibrio spp. in summer). Depuration was an efficient process to reduce the levels of E. coli and toxic elements (particularly Pb) in different bivalves to levels considered as acceptable for human consumption, but not to eliminate Vibrio spp. Transport at 4 °C was indeed the best solution to maintain good physiological conditions of clams and to avoid the Vibrio spp. growth. Despite invasive clam species demonstrated higher survival at lower temperatures compared to the native ones, they also revealed similar upper thermal tolerance limits. Distinct physiological requirements and mechanisms of defence against warming were observed: while the invasive closes the valves, the native uses glycogen and fatty acids as energy sources, and displayed higher metabolism, activity of antioxidant enzymes, heat shock proteins and lipid peroxidation. Overall, the main outputs of this dissertation allowed to correctly predict the risks associated with bivalve consumption to greatly improve the knowledge of stress physiology in native and invasive clams.
Os bivalves são extremamente importantes na economia e gastronomia portuguesa, sendo as amêijoas as principais espécies consumidas. Contudo, o seu consumo levanta preocupações acrescidas de segurança alimentar devido à acumulação de contaminantes biológicos, incluindo os microbiológicos e químicos, dado que são organismos filtradores que habitam em estuários constantemente sujeitos a contaminação e variabilidade climática. Neste contexto, os objetivos desta dissertação foram investigar o comportamento dos consumidores de bivalves, comparar as respostas microbiológicas, químicas e fisiológicas de amêijoas nativas e invasoras à depuração e transporte em condições semi‐secas a diversas temperaturas, e avaliar o impacto do aquecimento no metabolismo, stress oxidativo e qualidade nutricional. Os consumidores de bivalves apresentaram comportamentos de risco que diferem de acordo com as suas características demográficas e socioeconómicas. Foram observados níveis mais elevados de bactérias nas espécies invasoras, independentemente da época do ano e parâmetros ambientais (Escherichia coli e contagens totais de viáveis no inverno e Vibrio spp. no verão). A depuração revelou‐se eficiente na redução dos níveis de E. coli e elementos tóxicos (particularmente Pb) em diferentes bivalves para níveis considerados aceitáveis para consumo humano, mas não é eficiente na eliminação do Vibrio spp. O transporte a 4 °C permitiu melhores condições fisiológicas das amêijoas e evitou o crescimento de Vibrio spp. Apesar das amêijoas invasoras demonstrarem maior sobrevivência a temperaturas baixas em relação às nativas, mostraram igualmente limites de tolerância térmica superiores similares. Distintos requisitos fisiológicos e mecanismos de defesa contra o aquecimento foram observados: enquanto a invasora fechou as valvas, a nativa usou glicogénio e ácidos gordos como fontes de energia, e revelou maiores taxas metabólicas, atividades de enzimas antioxidantes, proteínas de choque térmico e peroxidação lipídica. Os resultados desta dissertação permitem compreender os riscos associados ao consumo de bivalves e os mecanismos fisiológicos de tolerância ao stress em amêijoas nativas e invasoras.
Fundação para a Ciência e a Tecnologia (FCT)

The major objectives of this research were to examine the bioaccumulation parameters [depuration rates (kd), half life (t1/2) and biomagnification factor (BMF)] of individual isomers of hexabromocyclododecane (HBCD, C12H18Br6) in fish and to test the hypothesis of in vivo bioisomerization. This was done by exposing three groups of juvenile rainbow trout (Oncorhynchus Mykiss) to food fortified with known concentrations of an individual diastereoisomer (α, β, γ) for 56 days (uptake phase) followed by 112 days (depuration phase) of unfortified food. A fourth group of fish were exposed to unfortified food for the duration of the experiment. Fish (n=4) from all four aquaria were sacrificed on days 0, 7, 14, 56, 63, 70, 112 and 168 and muscle tissue was extracted and analyzed for diastereoisomer concentrations by high performance liquid chromatography tandem mass spectrometry (LC/MS/MS). Bioaccumulation of the γ diastereoisomer was linear during the uptake phase while the α and β diastereoisomers were found to increase exponentially with respective doubling times of 14.1 and 20.5 days. Both the β and γ diastereoisomers followed first order depuration kinetics with calculated t1/2’s of 94 ± 25 and 84 ± 51 (± 1 × standard error) days, respectively. The BMF for the α diastereoisomer (BMF = 4.1) was one and a half times greater than the β-diastereoisomer (BMF = 2.6) and about one fifth larger than the γ-diastereoisomer (BMF = 3.6). The large BMF for the α diastereoisomer is consistent with this diastereoisomer dominating higher trophic level organisms in wildlife. Although the BMF of the β diastereoisomer suggests that it will biomagnify, because it is present in small quantities in commercial mixtures it is rarely detected in environmental samples. Results from these studies also provide evidence of bioisomerization of the β and γ diastereoisomers. Most importantly, the α diastereoisomer which was recalcitrant to bioisomerization by juvenile rainbow trout in this study and known to be the dominant diastereosiomer in fish, was bioformed from both the β and γ diastereoisomers. To our knowledge, this is the first report of bioisomerization of a halogenated organic pollutant in biota.
May 2006

The recurrent emergence of infections outbreaks associated with bivalve molluscs consumption is of extreme importance for public health. Aeromonas hydrophila is a human pathogen that is widely distributed in coastal areas, and is a causative agent of different diseases (e.g., gastroenteritis, wound infection, meningitis, endocarditis and septicaemia) in humans after consumption of contaminated seafood. Although bacterial elimination mostly depends on the depuration of bivalves, this process is not sufficiently safe and efficient to eliminate some microorganisms present in their tissues. The development and evaluation of new strategies with no adverse effects to bivalves, in order to reduce the concentration of potential human pathogens is therefore essential. One of the most promising approaches is to combine phage therapy with the depuration process. The use of bacteriophages (or phages) to control bacterial infections has been reported across numerous fields by many researchers. However, relatively the combination of depuration and phage therapy to eliminate pathogenic bacteria in bivalves there are only four studies, and these studies are restricted to three bacterial strains (Vibrio parahaemolyticus, Escherichia coli and Salmonella enterica serovar Typhimurium). Thus, the objective of this work was to evaluate the efficacy of three new phages to control A. hydrophila, in order to evaluate their potential application during depuration. Three new phages (AH-1, AH-4 and AH-5) were isolated and characterized in terms of host range, latent period, burst size, and development phage-resistant mutants. First, the phage-bacteria interaction was evaluated in vitro, using single suspensions of phages or phage cocktails. Time of treatment and the concentration of phage were also studied. The isolated phages, AH-1, AH-4 and AH-5, belonged to the Myoviridae family. In general, the increase of multiplicity of infection (MOI) from 1 to 1000 not promoted a significant increase in the efficiency of phage AH-1. The in vitro assays indicated that the use of phages AH-1, AH-4 and AH-5 can be an effective alternative to control of A. hydrophila, however, the phage AH-1 was the most efficient one (additional reduction of more 3 log CFU/mL) when compared with to the other two phages. The use of cocktails with two and three phages (AH-1/AH-4, AH-1/AH-5, AH4/AH-5 and AH-1/AH-4/AH-5) was lightly more effective (maximum reductions of 5.1-5.8 log CFU/mL) than the use of phages AH-4 and AH-5 alone (reductions of 4.9 and 4.5 log CFU/mL, respectively), however, the efficiency of phage AH-1 (maximum inactivation of 7.7 log CFU/mL) was significantly higher than the obtained with phage cocktails. Second, to confirm if the phage AH-1 can be used to control the A. hydrophila in bivalves, in vivo experiments, using artificially contaminated cockles were done. Depuration in static seawater at multiplicity of infection (MOI) of 1 with phage of AH-1 revealed a significantly decrease in the rate of A. hydrophila inactivation in cockles (1.0 log CFU/g) during treatment. Results indicated that combining phage biocontrol with depuration procedures enhance bivalve microbial safety for human consumption by improving decontamination efficiency, proving that this technology can be transposed to the bivalve industry.
O aparecimento recorrente de surtos infeciosos associados ao consumo de bivalves moluscos é de extrema importância para a saúde publica. Aeromonas hydrophila é uma bactéria patogénica amplamente distribuída nas zonas costeiras e é um agente causador de diferentes doenças (por exemplo, gastroenterite, infeção em feridas, meningite, endocardite e septicemia) no homem após o consumo de frutos do mar contaminados, nomeadamente bivalves. Embora a eliminação bacteriana dependa maioritariamente da depuração dos bivalves, este processo não é suficientemente seguro e eficiente para eliminar alguns microrganismos presentes nos tecidos dos bivalves. O desenvolvimento e avaliação de novas estratégias sem efeitos adversos para os bivalves, a fim de reduzir a concentração de potenciais agentes patogénicos, é, portanto, essencial. Uma das abordagens mais promissoras é a combinação da terapia fágica com a depuração. A eficácia da utilização de bacteriófagos (ou fagos) para controlar infeções bacterianas tem sido relatada em inúmeros estudos. No entanto, relativamente à utilização da terapia fágica para inativar bactérias patogénicas durante a depuração de bivalves, existe apenas quatro estudos, estando estes estudos restritos a três estirpes bacterianas (Vibrio parahaemolyticus, Escherichia coli e Salmonella enterica serovar Typhimurium). Assim, o objetivo deste trabalho foi avaliar a eficácia de três novos fagos para controlar A. hydrophila, de forma a estudar a sua potencial aplicação durante o processo de depuração. Foram isolados três novos fagos (AH-1, AH-4 e AH-5) que foram caracterizados em termos de gama de hospedeiros, período latente, número de explosão e desenvolvimento de mutantes resistentes aos fagos. Inicialmente, a interação fago-bactéria foi avaliada in vitro, utilizando suspensões individuais de fago e cocktails. O tempo de tratamento e concentração de fago a aplicar também foram estudados. Todos os fagos isolados, AH-1, AH-4 e AH-5 pertencem à família Myoviridae. Em geral, o aumento da multiplicidade de infeção (MOI) de 1 a 1000 não promoveu um aumento significativo na eficácia do fago AH-1. Os ensaios in vitro demonstraram que a utilização do fago AH-1, AH-4 e AH-5 pode ser uma alternativa eficaz no controlo de A. hydrophila, no entanto, o fago AH-1 foi mais eficaz (redução adicional superior a 3 log CFU/mL) quando comparado com os outros dois fagos. A utilização de cocktails com dois ou três fagos (AH-1/AH-4, AH-1/AH-5, AH-4/AH-5 e AH-1/AH-4/AH-5) foi ligeiramente mais eficaz (redução máxima de 5,1 a 5,8 log CFU/mL) do que a obtida com os fagos AH-4 e AH-5 (redução de 4,9 e 4,5 log CFU/mL, respetivamente), no entanto, a eficácia do fago AH-1 (inativação máxima de 7,7 log CFU/mL) foi maior do que a obtida com os cocktails de fago. Numa segunda fase, para confirmar se o fago AH-1 pode ser usado para controlar a A. hydrophila em bivalves, foram realizados ensaios in vivo utilizando berbigões artificialmente contaminados. A depuração num sistema estático com MOI de 1 usando o fago AH-1 levou a uma diminuição significativa (1,0 log CFU/g) na concentração de A. hydrophila nos berbigões. Os resultados indicam que a combinação do fago AH-1 com a depuração aumenta a segurança dos bivalves para consumo humano, melhorando a eficácia da descontaminação, sugerindo, que esta tecnologia pode ser aplicada na indústria de bivalves.
Mestrado em Microbiologia

Oysters are filter-feeding bivalves, which filter water for nutrients and often accumulate contaminants and human pathogens such as Vibrio parahaemolyticus and Vibrio vulnificus naturally occurring in the marine environment. These naturally occurring pathogens have been frequently isolated from raw shellfish, particularly oyster, in the United States and are recognized as the leading causes of human gastroenteritis associated with seafood consumption. Human illness caused by consumption of raw oyster contaminated with V. parahaemolyticus and Vibrio vulnificus typically results in reduced sales of oysters and a consequent significant financial burden for the producers. The United States produces more than 27 million pounds of oysters each year with a large portion of them being produced from the coastal water of the Gulf of Mexico. It is estimated that 20 million Americans eat raw shellfish and consumption of raw oyster is responsible for about 95% of all deaths associated with seafood consumption in the U.S., making raw oysters one of the most hazardous seafoods. Several post-harvest processes, including low temperature pasteurization, freezing, high pressure processing and irradiation, have been reported capable of reducing Vibrio contamination in raw oysters. However, most of them require either a significant amount of initial investment or operation costs, and oysters are often killed during processing. Cost-effective post-harvest processing for reducing V. parahaemolyticus in raw oysters without significant adverse effects on the oysters remains to be developed. This study was conducted to determine impacts of low-temperature (15, 10 and 5°C) depuration and frozen storage on reducing V. parahaemolyticus and V. vulnificus in raw oysters. Depuration of the Gulf oyster (Crassostrea virginica) with electrolyzed oxidizing (EO) water (chlorine, 30 ppm; pH 2.82; oxidation-reduction potential, 1,131mV) containing 3% NaCl was found ineffective on reducing both V. parahaemolyticus and V. vulnificus in the oysters. Reductions of V. parahaemolyticus and V. vulnificus in oyster after 48 h of EO water depuration at 22°C were limited to 0.7 and 1.4 log MPN/g, respectively. Depuration with EO water at lower temperatures did not enhance reductions of Vibrio in the oysters. Greater reductions of V. parahaemolyticus (1.2 log MPN/g) and V. vulnificus (2.0 log MPN/g) were observed when the oysters were depurated with artificial seawater (ASW) at room temperature (22°C) for 48 h. Decreasing temperature of ASW to 15°C for depuration significantly increased the reductions of V. parahaemolyticus and V. vulnificus to 2.1 and 2.9 log MPN/g, respectively, after 48 h of process. However, depuration of oyster in ASW at 10 and 5°C were found less effective than at 15°C in reducing Vibrio in the Gulf oysters. An extended depuration with ASW at 15°C for 96 h was capable of achieving 2.6 and 3.3 log MPN/g of reductions of V. parahaemolyticus and V. vulnificus, respectively, in the Gulf oysters. Study of effects of frozen storage at -10, -23 and -30°C on reducing V. parahaemolyticus in raw half-shell Pacific oyster (Crassostrea gigas) found that the population of the bacterium decreased faster in oysters stored at -10 than at -23 or -30°C. Holding half-shell Pacific oyster at -10°C for three months or at -23°C for four months was capable of achieving a greater than 3-log (MPN/g) reduction of V. parahaemolyticus in the Pacific oyster.
Graduation date: 2008