Former mining areas are well-known globally to be a significant anthropogenic source of contaminants being dispersed into the surrounding environment. Various human activities, including ore mineral mining, industrial activities, domestic waste production, and the agricultural application of fertilisers and pesticides, are likely to contribute to the release of huge amounts of potentially toxic metals into the ecosystem, which have harmful effects on the flora and fauna and on human health. Therefore, the main aim of this study is to evaluate the contamination that arises from some selected heavy metals (Cu, Pb, Zn, Mn, Cr, Ni, and V) in topsoil and floodplain samples from the Ecton mining area. Ecton Hill is located in the southern part of the Peak District, Staffordshire, England, and bounded by the River Manifold from the west. This area has been mined for sulphide minerals, which were extracted extensively from the 16th century until the mid-19th century; the area is currently being used for cattle rearing and agricultural purposes. Therefore, it would be worth finding out the extent to which the area has been polluted by the aforementioned metals. To this end, topsoil and floodplain samples were collected and analysed for their total concentrations using XRF technique and different granulometric classes (i.e. clay, silt, and sand) using a (Malvern Mastersizer Long Bed) laser granulometer with a presentation unit of MS-17. In addition, soil specific factors, including organic matter content, organic carbon, pH, Eh, and cation exchange capacity were also measured. Spatial distribution maps were constructed using a GIS approach for the metals studied over the study area. Contamination and ecological risk assessments were carried out via the geoaccumulation index (Igeo) and enrichment factors (EF) respectively. Moreover, collected soils for different land uses have been assessed using the UK government soil guidelines (i.e. ICRCL and CLEA's SGVs soil values). Furthermore, the bioavailability, leachability, and fractionation (using five-steps sequential extraction) of the metals in various soil phases were characterised using correlation matrix and principal component analysis (PCA) approaches. The GIS- based spatial analysis maps reveal that elevated concentrations of the metals are located around the sites of the mining waste in the area. The contamination assessment results indicate that Cu, Pb, Zn have a contamination degree ranging between strongly contaminated (class 4) and extremely contaminated (class 6). The results of the ecological assessment by enrichment factor (EF) show that Pb has the highest enrichment factor. The bioavailability results of the heavy metals under study, via EDTA, show that Cu, Pb, Zn have the highest bioavailable fractions. The regression analysis demonstrates that Mn gives the best fit regression equation with the highest R2 value of 0.825. The leachability results reveal that, of the seven heavy metals, Zn has the highest leachable value, whereas the lowest leachable was recorded for Cr. Speciation was measured using the five-steps procedure, and the results show that Cu, Pb and Zn are mainly associated with the organic matter fraction, whilst, Cr, Ni and V are associated with the residual fraction. The principal component analysis (PCA) revealed that oxides of Fe/Al, organic matter, and the clay and silt fractions are the main soil parameters responsible for binding heavy metals to the soil surfaces of the study area. Changing the redox potential conditions and acidification was investigated and the results indicate that such changes have significant effects on the release of heavy metals from the soil particles at Ecton Hill.

O uso da irrigação em cafeeiro é uma tecnologia que vem se consolidando e mostrando-se economicamente viável ao longo dos tempos, trazendo junto com ela a técnica da fertirrigação. Desta forma, o presente estudo teve como objetivo avaliar a influência de formas de aplicação e fontes de fertilizantes sobre a condutividade elétrica e pH da solução do solo, bem como no desenvolvimento e produção do café conilon irrigado por gotejamento. O trabalho foi desenvolvido em São Gabriel da Palha, Espírito Santo, utilizando o clone 12V da variedade INCAPER 8142. O experimento foi delineado em blocos ao acaso (DBC) com seis tratamentos e quatro blocos. Os tratamentos adotados foram: T1 - Controle - adubação nitrogenada e potássica aplicada via solo nas fontes ureia e cloreto de potássio; T2 - Adubação nitrogenada e potássica aplicada via solo nas fontes ureia e cloreto de potássio de liberação controlada; T3 - Adubação nitrogenada e potássica aplicada via fertirrigação nas fontes ureia e cloreto de potássio; T4 - Adubação nitrogenada e potássica aplicada via fertirrigação nas fontes nitrato de amônio e sulfato de potássio; T5 - Adubação nitrogenada e potássica aplicada via fertirrigação nas fontes nitrato de amônio e nitrato de potássio; T6 - Adubação nitrogenada e potássica aplicada via solo nas fontes ureia e cloreto de potássio de liberação controlada no período de outubro a março (período chuvoso) e adubação nitrogenada e potássica aplicada via fertirrigação, nas fontes nitrato de amônio e sulfato de potássio no período de abril a setembro (período seco). Foi monitorado o pH e condutividade elétrica da solução do solo, avaliações biométricas das plantas tais como altura, comprimento do primeiro ramo plagiotrópico e número de nós no primeiro ramo plagiotrópico, além da produção por planta e estimativa de produtividade. Os tratamentos T1 e T3 que utilizaram ureia e cloreto de potássio e o T4 - nitrato de amônio e sulfato de potássio disponibilizaram maiores quantidade de nitrogênio na forma amoniacal, causando maior acidificação do bulbo. Em contrapartida os tratamentos T2, T5 e T6 apresentaram menor acidificação, com diferença estatística significativa na variação do pH nas duas profundidades analisadas a partir de 18 meses da aplicação dos tratamentos. Nos tratamentos T2 e T6 observou-se menor salinidade inicial na avaliação aos 90 dias após o plantio através da leitura da condutividade elétrica da solução do solo. Para as avaliações biométricas, os tratamentos T2, T4, T5 e T6 diferiram estatisticamente dos tratamentos T1 e T3, influenciando positivamente à altura de plantas, comprimento e número de nós no primeiro ramo plagiotrópico. / Fertigation is a widespread technology in coffee cultivation; however, with the insertion of new fertilizers technologies, new studies are required. This study aims to evaluate the influence of application types and fertilizers sources on the electrical conductivity and pH of the soil solution in the wet bulb as well its influence in the development and production of drip irrigated conilon coffee. The study was conducted in São Gabriel da Palha, Espírito Santo (Brazil), using 12V clone variety INCAPER 8142. The experiment was designed in randomized blocks (DBC) with six treatments and four blocks. The adopted treatments were: T1 - Control / nitrogen and potassium fertilization applied via soil: urea and potassium chloride; T2 - Nitrogen and potassium fertilization applied via soil : urea and potassium chloride with release controlled; T3 - Nitrogen and potassium fertilization applied by fertigation: urea and potassium chloride; T4 - Nitrogen and potassium fertilization applied by fertigation: ammonium nitrate and potassium sulfate; T5 - Nitrogen and potassium fertilization applied by fertigation: ammonium nitrate and potassium nitrate; T6 - Nitrogen and potassium fertilization applied via soil: urea and potassium chloride with controlled release in the period from October to March (rainy season) and nitrogen and potassium fertilization applied by fertigation, ammonium nitrate and potassium sulphate in the period from April to September (dry season). The biometric evaluations of the plants were: height, length of the first branch and number of nodes in the first plagiotrophycal in addition to production per plant and productivity estimate. T1 and T3 treatments using immediate solubility of urea and T4 - ammonium nitrate have provided large amount of nitrogen in the ammonium form, causing increased acidification in the bulb. In contrast the T2, T5 and T6 treatments had lower acidification, with statistically significant differences in the pH variation in two depths analyzed from 18 months of treatment application. In treatments T2 and T6 it was observed lower initial salinity in the evaluation at 90 days after planting through the EC reading. To biometric assessments, treatments T2, T4, T5 and T6 differ statistically from T1 and T3, influencing plant height, length and number of nodes in the first plagiotrophycal.

Submitted by William Justo Figueiro (williamjf) on 2015-07-20T22:41:53Z No. of bitstreams: 1 56c.pdf: 3770514 bytes, checksum: cf71b027cc3d4c64d9a8799069053dd1 (MD5) / Made available in DSpace on 2015-07-20T22:41:53Z (GMT). No. of bitstreams: 1 56c.pdf: 3770514 bytes, checksum: cf71b027cc3d4c64d9a8799069053dd1 (MD5) Previous issue date: 2014-07-31 / Nenhuma / As culturas tradicionais de bactérias lácticas utilizadas para elaboração dos leites fermentados pós-acidificam mesmo em temperatura de refrigeração. Uma seleção cuidadosa poderia reduzir os impactos causados pelas falhas na cadeia do frio e melhorar a qualidade sensorial dos produtos oferecidos ao mercado consumidor. Diante disso, o objetivo deste trabalho foi selecionar culturas microbianas adequadas para o laticínio, sendo que a principal característica buscada foi baixa pós-acidificação e aumento de viscosidade do iogurte e da bebida láctea. Foram avaliadas as três culturas atualmente utilizadas pelo laticínio e cinco novas culturas para os produtos bebida láctea e iogurte. Para ambas as culturas foi verificado o tempo de fermentação, a pós-acidificação quando o produto era mantido em temperatura de fermentação, além do pH e viscosidade durante o shelf life, quando o produto era resfriado à 10 e 15 °C antes do envase. Os resultados mostraram elevada pós-acidificação e baixa viscosidade para duas culturas atualmente utilizadas pela empresa, as quais foram descontinuadas. Três novas culturas apresentaram resultados satisfatórios para o objetivo proposto. Foi possível concluir que a escolha da cultura microbiana interfere fortemente na pós-acidificação e viscosidade para o produto bebida láctea e que a interferência não é tão significativa para o produto iogurte. Através da realização deste trabalho foi verificado que o shelf life da bebida láctea poderia ser aumentado de 45 para 60 dias. / The traditional cultures of lactic acid bacteria used in the preparation of fermented milk post-acidify even at refrigeration temperature. A careful selection could reduce the impacts caused by failures in the cold chain and improve the sensory quality of products offered to the consumer market. Therefore, the aim of this study was to select appropriate microbial cultures for the dairy industry, and the main feature was sought low post acidification and viscosity increase of fermented milks. The three cultures currently used in the dairy industry and five new cultures for yogurt and fermented dairy drink products were evaluated. Fermentation time was checked for both cultures, when the after acidification from the product was maintained at a temperature of fermentation, addition of pH and viscosity during the shelf life, when the product was cooled at 10 and 15 º C before packaging. The results show low viscosity and high post acidification for two currently cultures used by the company, which were discontinued. Three new cultures showed satisfactory results for the proposed objective. It was concluded that the choice of the microbial culture interferes strongly in the post acidification and viscosity for the product fermented dairy drink and that interference is not as significant for the yogurt product. Through this study it was found that the shelf life of fermented milk could be increased from 45 to 60 days.

Thesis: Ph. D., Joint Program in Biological Oceanography (Massachusetts Institute of Technology, Department of Biology; and the Woods Hole Oceanographic Institution), 2017. / Cataloged from PDF version of thesis. / Includes bibliographical references (pages 159-168). / Thecosome pteropods are planktonic mollusks that form aragonite shells and that may experience increased dissolution and other adverse effects due to ocean acidification. This thesis focuses on assessing the possible biological effects of ocean acidification on the shells and locomotion of pteropods and examining the response of a local pteropod population to environmental change over time. I analyzed shell condition after exposing pteropods to elevated CO₂ as well as in natural populations to investigate the sensitivity of the shells of different species to aragonite saturation state ([omega][subscript A]). The pteropods (Limacina retroversa) from laboratory experiments showed the clearest pattern of shell dissolution in response to decreased [omega][subscript A], while wild populations either had non-significant regional trends in shell condition (Clio pyramidata) or variability in shell condition that did not match expectations due to regional variability in [omega][subscript A] (Limacina helicina). At locations with intermediate [omega][subscript A] (1.5-2.5) the variability seen in L. helicina shell condition might be affected by food availability more than tA. I examined sinking and swimming behaviors in the laboratory in order to investigate a possible fitness effect of ocean acidification on pteropods. The sinking rates of L. retroversa from elevated CO₂ treatments were slower in conjunction with worsened shell condition. These changes could increase their vulnerability to predators in the wild. Swimming ability was mostly unchanged by elevated CO₂ after experiments that were up to three weeks in duration. I used a long-term dataset of pteropods in the Gulf of Maine to directly test whether there has been a population effect of environmental change over the past several decades. I did not observe a population decline between 1977 and 2015, and L. retroversa abundance in the fall actually increased over the time series. Analysis of the habitat use of L. retroversa revealed seasonal associations with temperature, salinity, and bottom depths. The combination of laboratory experiments and field surveys helped to address gaps in knowledge about pteropod ecology and improve our understanding of the effects of ocean acidification on pteropods. / by Alexander Bergan. / Ph. D.

A normalização é uma importante etapa da Avaliação do Ciclo de Vida, uma vez que fornece uma unidade comum, permitindo a comparação das diferentes categorias de impacto. A referência de normalização mais utilizada considera o impacto das atividades totais da sociedade num certo período de tempo. Estes dados são inexistentes no Brasil para impactos regionais e locais, de forma que este trabalho objetivou iniciar o preenchimento dessa lacuna, com os fatores de normalização para as categorias \"acidificação\" e \"eutrofização\", no estado de São Paulo. Tais fatores foram calculados com base em um inventário das estimativas anuais de aporte ao meio ambiente de substâncias contribuintes para estas categorias, cuja realização possibilitou a análise do estado da arte desses impactos em São Paulo e dos setores responsáveis pela geração das substâncias contribuintes. Conforme esperado, os fatores (ou referências) de normalização encontrados foram diferentes daqueles por hora utilizados no Brasil, baseados em dados europeus. Entre as razões que explicam esta diferença estão a baixa emissão de \'SO IND.X\' devido a matriz energética brasileira, o uso de etanol com combustível e o despejo de esgoto sem tratamento (ou tratamento inadequado). / Normalization is an important step in Life Cycle Assessment as it provides a common unit, allowing the comparison of the different impact categories. The normalization reference most widely used considers the \"background\" impact from the total activities of society in a chosen reference period. These data are inexistent in Brazil for regional and local impacts so that this work aimed to begin filling this lack, first developing normalization factors for the categories \"acidification\" and \"eutrophication\" in the state of Sao Paulo. These factors were calculated from an inventory of the annual load to the environment of substances contributing to these categories; the production of this inventory allowed the analysis of a) the state of the art of these impacts in Sao Paulo and b) the sectors responsible for the generation of contributors. As expected, normalization factors (or references) were different from those currently used in Brazil, based on European data. Among the reasons for this difference are lower \'SO IND.X\' emissions due to the Brazilian energy matrix, the use of ethanol as fuel and disposal of sewage without treatment (or mistreatment).

This thesis deals with forms of aluminium occurring in acidified surface waters. Special attention is paid to inorganic monomeric aluminium, fraction, which has toxic effect on some species of aquatic and terrestrial biota. The thesis primarily focuses on the analysis of surface water, groundwater and soil water chemistry in the year-round and long-term monitoring. The practical took place on an experimental mountain basin Uhlířská, which is drained by river Černá Nisa. Uhlířská basin is located in the Jizera Mountains and represents the area which was significantly exposed to the acid atmospheric deposition in the second half of the 20th century. Long-term exposure to acid precipitation caused the acidification of soil and watercourses, forest degradation and deforestation of large parts of the basin. Decrease in pH and an increase in concentration of toxic aluminium also caused species depletion of aquatic ecosystems. Monomeric forms of aluminium were determined spectrophotometrically, the concentration of total aluminium was determined by the method of flame atomic absorption spectrometry (FAAS), in case of low concentration electrothermal atomic absorption spectrometry (ETAAS) was used. Five forms of aluminium were obtained - Altot, AlAS, Alm, Alo and potentially toxic Ali. Appart from...

Diante do quadro atual de previsões de mudanças climáticas, estudos a respeito das possíveis respostas dos organismos a estas alterações são importantes. Com a finalidade de prever e verificar se estas serão de fato deletérias ou se os organismos são capazes de lidar com elas sem alterações na sua fisiologia, e consequentemente na estrutura do ambiente, E. brasiliensis foi utilizada como modelo para estudar possíveis impactos do aumento da temperatura e acidificação dos oceanos na sua fisiologia. Para isso, espécimes foram expostos a 9 possíveis combinações de temperatura (24ºC, 28ºC e 30ºC) e pH (8.0, 7.7 e 7.3) em diferentes intervalos de tempo (1, 3, 12, 24 e 48 h). Amostras de gônadas e fluido celomático foram coletadas para avaliar a expressão das proteínas de estresse HSP70, AIF-1 e p38-MAPK, e a variação no número e viabilidade dos celomócitos. Nossos resultados mostram que o modelo é sensibilizado pelas mudanças no ambiente, através da hiper-regulação das proteínas de estresse. O cenário considerado mais extremo (30°C + pH7.3) ocasionou a morte de 100% dos organismos após 24horas. E o segundo cenário mais severo (30°C + pH7.7) desencadeou o desenvolvimento de ulceração de pele. Os efeitos são mais pronunciados nos celomócitos e a acidificação da água parece ter efeitos antagônicos com a temperatura nos celomócitos e sinérgicos nas gônadas. Embora a resposta tenha sido sistêmica, o grau e a dinâmica foram distintos em relação às diferentes amostras e estresses. Podendo causar modificações na resposta imune dos organismos e consequentemente na sobrevivência da espécie a longo prazo. / Under the current Climate Change context, studies about the potential responses of the organisms to their changing environment are of extreme importance. Recent studies point out the synergy of temperature and ocean acidification altogether. In this study, we used the sea star E. brasiliensis to assess the physiological effects of rising temperature, seawater acidification and the interaction of both factors. Independent individuals (N=225) were exposed to 9 possible combinations of temperature (24ºC, 28ºC and 30ºC) and pH (8.0, 7.7 and 7.3), for 1, 3, 12, 24 and 48 h. We compared the stress produced by these treatments measuring the expression of heat shock proteins (HSP70), the production of the allograft inflammatory factor (AIF−1) and the activation of mitogen kinases (MAPKs) at both gonad and celomic fluid. Furthermore, we assessed the quantity and quality of coelomocytes. Our results demonstrated that E. brasiliensis is vulnerable to the interaction of temperature and acidification. All the stress proteins evaluated were upregulated. The extreme scenario (30°C + pH7.3) caused the death of 100% of organisms after 24 hours, while the second most severe scenario (30°C + pH7.7) triggered skin ulceration. Nevertheless, we found that water acidification produces antagonistic effects to the temperature in coelomocytes and synergistic effects in gonad cells. Furthermore, these effects were more pronounced in the coelomocytes than in the gonads. The systemic response found in this study suggest that the interactive effects of elevated temperatures in conjunction with ocean acidification may endanger the survival of this species, and it could compromise the ecosystem functioning at long term.

Increasing concentrations of atmospheric CO2 are in dynamic equilibrium with the oceans. The absorption of CO2 by seawater causes a decrease in seawater pH and calcite saturation state (SS). This process, termed ocean acidification, exerts deleterious effects on marine calcifiers. Studies of symbiont-bearing large benthic foraminifera (LBF) have reported a generally unfavorable response to increased concentrations of carbon dioxide ([CO2]). Experiments and analyses were undertaken to examine the effect of increased [CO2] on the growth rate, ultrastructure, stable isotopes of carbon and oxygen, as well as Mg/Ca of the high-Mg miliolid Archaias angulatus and the low-Mg rotalid Amphistegina gibbosa. A CO2-injection culture study was performed at pH 8.0, 7.8 and 7.6, corresponding to CO2 concentrations of approximately 400 ppm, 800 ppm, and 1,300 ppm. After 2, 4, or 6 weeks of treatment, bags containing groups of approximately 20 previously-imaged live specimens were removed and prepared for the aforementioned analyses. Archaias angulatus responded to increased [CO2] by reducing test growth rate at 1,300 ppm CO2 (pH 7.6) by 50% (p < 0.01, r2 = 36%), increasing its pore area (F(2,3477) = 103.37, p West Florida shelf LBF carbonate production attributed to LBF was estimated by combining interpolations of SS calcite at three treatment levels, corresponding to pH 8.1 (400 ppm CO2), pH 7.8 (800 ppm CO2), and pH 7.6 (1,300 ppm CO2), with a map of the carbonate fraction of seafloor sediment. Growth rates for 10 species were estimated in a meta-analysis of culture studies; these rates were used to model the response of miliolids and rotalids to increased [CO2]. In the model, rotalids responded to higher CO2 concentrations by reducing their average adult size by 20% at 800 ppm CO2 and 40% at 1,300 ppm CO2. Miliolids responded by reducing their average adult size by 40% at 800 ppm CO2 and 75% at 1,300 ppm CO2. Modeled LBF carbonate production for the west Florida shelf is 7 Mt at 400 ppm, 4.8 Mt at 800 ppm, and 2.5 Mt at 1,300 ppm. In a high CO2 world, low-Mg rotalids exhibit modest reductions in test growth rates and carbonate production, whereas high-Mg miliolids exhibit major reductions in test growth rates and carbonate production.

The airway surface contains a number of important defense mechanisms to protect against infection. Antimicrobials found in the thin layer of fluid lining the airways, the airway surface liquid (ASL), rapidly kill bacteria. Another defense mechanism, mucociliary transport, propels foreign particles and mucus out of the airways. These and potentially other host defense properties show a dependence on the pH of the ASL. An acidic ASL pH reduces bacterial killing by cationic antimicrobial peptides, and increases ASL viscosity, potentially effecting mucociliary transport. Consequently, an acidic ASL pH can impair airway host defense. An example of a disease where an acidic ASL pH impairs airway host defense, is Cystic Fibrosis (CF). The major cause of morbidity and mortality in CF is airway infections. Humans with CF and the CF pig model develop airway infections. But curiously CF mice are spared. Compared to non-CF, people with CF and CF pigs show an abnormally acidic ASL pH. However, the ASL pH in CF mice is not different to that of non-CF. Thus, we hypothesized that CF mice do not show defects in airway host defense because their ASL pH is not acidic compared to non-CF. As pH is a balance between acid and base secretion, we first determined which HCO3- and H+ secreting proteins contribute to ASL pH and the differences between humans, pigs, and mice. CF is caused by defects in an anion channel, CFTR. We found that in all three species, CFTR secreted HCO3- into the ASL, which was absent when CFTR was defective. To determine how much CFTR is required to rescue ASL pH and host defense properties, we mixed CF and non-CF airway epithelia from newborn pigs in different ratios. HCO3- secretion, ASL pH, and host defense properties showed a direct relationship to CFTR, suggesting that CFTR was the rate-limiting step. As CFTR was limiting, we found that supernormal CFTR expression in a small number of cells could dramatically increase ASL pH, suggesting viral-mediated gene therapy approaches may have benefit for CF. We found that Ca2+ activated Cl- channels also played some role in ASL pH in CF pigs and CF mice. However, as CF pigs develop airway infection, while CF mice do not, this suggested that other factors might be important for differences in ASL pH and consequently the development of disease. To further investigate the determinants of ASL pH, we examined H+ secretion. Humans and pigs showed 6 times more H+ secretion compared to mice. This acidification occurred through the non-gastric H+/K+ ATPase (ATP12A). ATP12A was also much more highly expressed in human and pig airways compared to mice. Blocking ATP12A in human and pig airways increased ASL pH and consequently improved host defense properties such as bacterial killing and ASL viscosity. Conversely, expressing ATP12A in CF mouse airways acidified ASL, impaired defenses, and increased airway bacteria. These findings suggest that ASL pH is a balance between HCO3- and H+ secretion. In humans and pigs lacking CFTR, unchecked H+ secretion by the non-gastric H+/K+ ATPase (ATP12A) acidifies the ASL, which impairs airway host defenses. However, as mouse airways expressed little ATP12A and secrete minimal H+, loss of CFTR does not lead to ASL acidification, protecting CF mice. These findings not only help explain why CF mice are protected from infection, but also nominate ATP12A as a therapeutic target for improving ASL pH and host defense in humans with CF.

Ce travail de thèse vise l'étude des effets des étapes de récolte et de concentration des cellules, sur la dégradation des fonctionnalités de Lactobacillus delbrueckii subsp. bulgaricus CFL1. Cet objectif s'accompagne de l'identification des mécanismes physiologiques qui expliquent les différences observées. La mise en œuvre de conditions de stress modéré, permettant aux cellules de s'adapter au stress ultérieur de congélation, constitue le troisième volet abordé dans cette thèse. Lors de la première partie du travail, l'effet d'une acidification en fin de fermentation sur la cryotolérance des cellules a été analysé. Un plan d'expériences a permis de définir la condition optimale d'acidification (pH 5,25 pendant 30 min) induisant une adaptation des cellules. Elle conduit à une meilleure résistance à la congélation et au stockage à -20 °C. Deux mécanismes physiologiques à l'origine de cette adaptation ont été identifiés. Le premier est lié à l'augmentation de la concentration de l'acide gras membranaire C18:1. Le deuxième, caractérisé pour l'analyse du protéome cytoplasmique, correspond à une réduction du métabolisme azoté, une augmentation des métabolismes énergétique et nucléotidique, et à une synthèse plus importante de protéines de stress. Dans une deuxième étape, les cellules ont été concentrées selon différentes conditions de centrifugation (vitesse de rotation, durée et température). Celles-ci n'ont pas d'effet sur la résistance de Lb. bulgaricus CFL1 à l'étape de concentration elle-même, mais présentent un effet faible mais significatif sur leur cryotolérance. Les évolutions de la résistance des cellules à la congélation et au stockage étant opposés, l'effet des conditions de centrifugation sur les cellules stockées à long terme est cependant négligeable. La troisième partie de ce travail a permis de quantifier l'impact de la concentration des cellules par microfiltration, sur leur résistance aux différentes étapes du procédé et sur l'état physiologique de Lb. bulgaricus CFL1. Les résultats montrent que les cellules sont moins résistantes à l'étape de microfiltration qu'à la centrifugation. Par contre, la résistance à la congélation augmente significativement (entre 28 % et 88 %) selon les conditions de microfiltration appliquées, par rapport à la centrifugation. La meilleure cryotolérance a été obtenue pour une vitesse tangentielle égale à 2,01 m.s-1 et une pression transmembranaire de 0,15 MPa. Cette meilleure résistance est liée à une augmentation des teneurs en acides gras C16:0, 18:1 et cycC19:0, ainsi qu'à une réduction de la concentration en C14:0. Les résultats des analyses protéomiques montrent aussi que les cellules les plus actives et les plus résistantes voient leur métabolisme énergétique augmenter, alors que leur métabolisme général et azoté est, au contraire, réduit. Finalement, ce travail propose deux voies intéressantes pour l'adaptation de Lb. bulgaricus CFL1, en vue d'améliorer sa cryotolérance. Certaines réponses physiologiques générales induisant ces adaptations cellulaires ont pu être identifiées, aux niveaux membranaire et cytoplasmique.