<p>Pectinases are a group of enzymes produced by bacteria, fungi, higher plants and animals. Pectinases can modify and degrade pectins, a class of heterogeneous and multifunctional polysaccharides present in middle lamellae and primary cell walls of plants. Pectins have been showed to play diverse roles in cell physiology, growth, adhesion and separation. Pectinases are used technically in the processing of fiber production and fruit juice or wine making. We have studied the mechanisms and applications of pectinases, especially in retting, a microbiological process where bast fibers in flax and other bast fiber cultivars are released from each other and from the woody core.</p><p>A strong correlation was found between the ability to perform retting and the degradation of sparsely esterified pectin, a substrate of polygalacturonase. This led to the conclusion that polygalacturonase plays a key role in the enzymatic retting of flax. We purified and characterized an extracellular polygalacturonase produced by Rhizopus oryzae, a very potent retting organism. The purified enzyme which appeared to be the single active component in retting, has non-methylated polygalacturonan as its preferred substrate. Peptide sequences indicate that the enzyme, like another polygalacturonase (EC. 3.2.1.15), belongs to glycosyl hydrolase family 28. It contains, however, an N-terminal sequence absent from other fungal pectinases, but present in an enzyme from the phytopathogenic bacterium, Ralstonia solanacearum.</p><p>Our finding that removal of calcium ions from the plant material by pre-incubation in dilute acid in enzymatic retting could reduce enzyme consumption by several orders of magnitude, improves the economical feasibility of the enzymatic retting process. Comparisons with different acids showed that the action was mainly pH dependent.</p><p>Pectinases were employed as analytical tools in a study of stored wood discoloration and, together with cellulases, in a mechanical process for making pulp from flax and hemp in paper production. </p>

Pectinases are a group of enzymes produced by bacteria, fungi, higher plants and animals. Pectinases can modify and degrade pectins, a class of heterogeneous and multifunctional polysaccharides present in middle lamellae and primary cell walls of plants. Pectins have been showed to play diverse roles in cell physiology, growth, adhesion and separation. Pectinases are used technically in the processing of fiber production and fruit juice or wine making. We have studied the mechanisms and applications of pectinases, especially in retting, a microbiological process where bast fibers in flax and other bast fiber cultivars are released from each other and from the woody core. A strong correlation was found between the ability to perform retting and the degradation of sparsely esterified pectin, a substrate of polygalacturonase. This led to the conclusion that polygalacturonase plays a key role in the enzymatic retting of flax. We purified and characterized an extracellular polygalacturonase produced by Rhizopus oryzae, a very potent retting organism. The purified enzyme which appeared to be the single active component in retting, has non-methylated polygalacturonan as its preferred substrate. Peptide sequences indicate that the enzyme, like another polygalacturonase (EC. 3.2.1.15), belongs to glycosyl hydrolase family 28. It contains, however, an N-terminal sequence absent from other fungal pectinases, but present in an enzyme from the phytopathogenic bacterium, Ralstonia solanacearum. Our finding that removal of calcium ions from the plant material by pre-incubation in dilute acid in enzymatic retting could reduce enzyme consumption by several orders of magnitude, improves the economical feasibility of the enzymatic retting process. Comparisons with different acids showed that the action was mainly pH dependent. Pectinases were employed as analytical tools in a study of stored wood discoloration and, together with cellulases, in a mechanical process for making pulp from flax and hemp in paper production.

Afin de mieux comprendre et évaluer l'impact du changement climatique sur les stocks de carbone organique du sol (COS) et les flux de carbone, et en particulier la respiration hétérotrophe du sol (RS), il est nécessaire d'étudier la sensibilité de la RS à la température. Plusieurs études sur les facteurs contrôlant la dépendance de la RS à la température ont été faites antérieurement et montrent que la sensibilité de la RS à la température diminue avec la température. Ces études ont suggéré que cette diminution de sensibilité de la RS à la température était liée à la modification de la disponibilité en substrat. D'autres études ont suggéré que cette diminution est liée à l'adaptation de la communauté microbienne aux températures élevées. La sensibilité de la RS à la température est plus particulièrement critique dans les régions semi-arides, comme le Nord Ouest de la Tunisie où le stock de COS est faible. Il est nécessaire de connaître l'effet de la disponibilité en substrat sur la sensibilité de la RS à la température. Dans cette étude, les échantillons de sol ont été incubés pendant 28 jours après une période de 28 jours de pré-incubation. Les pré-incubations et incubations ont été réalisées à 20, 30, 40 et 50°C. Pour tester l'effet de la disponibilité en substrat sur la sensibilité de la RS à la température, du glucose a été ajouté au sol au début de la période d'incubation. L'analyse des résultats a montré que les températures élevées de pré-incubation réduisent la sensibilité de la RS à la température d'incubation. L'addition de glucose réduit l'effet de températures élevées de pré-incubation sur la réponse de la RS. Il apparaît ainsi que la diminution de la sensibilité de la RS après un mois de pré-incubation aux fortes températures est due à la diminution de la disponibilité en substrat. Elle semble aussi liée à une diminution de la biomasse microbienne. Puisque, le sol utilisé pour cette étude est un Cambi sol Calco-magnésimorphe, une deuxième expérimentation a été réalisée afin de déterminer la part de CO2 provenant des carbonates et la part de CO2 provenant du COS. Cette étude a été réalisée par des mesures des signatures isotopiques (δ13C) du COS, des carbonates et du CO2 émis. Après 28 jours d'incubation, 23±9% de CO2 provient des carbonates. Cette contribution est faible par rapport à la teneur initiale élevée de C-CaCO3 dans le sol (4,3%) et est indépendante de la température d'incubation. Cette étude a montré que la réduction de la sensibilité de la RS aux fortes températures est surtout liée à une réduction de la disponibilité en substrat organique et de la biomasse microbienne aux fortes températures. / To better understand and assess the impact of climate change on the stocks of soil organic carbon (SOC) and carbon fluxes, and particularly heterotrophic soil respiration (SR), it is necessary to study the sensitivity of SR to temperature. Several studies have been achieved to improve the understanding of factors controlling the temperature dependence of SR and showed that the temperature sensitivity of SR decreases with temperature. These studies suggested that this decrease in temperature sensitivity of SR was related to change in substrate availability. Other studies presented microbial adaptation to warmed conditions. The temperature sensitivity of SR is especially critical in semi-arid regions, such as North West Tunisia, where the SOC stock is low. It is necessary to know the influence of substrate availability on the sensitivity of SR to temperature. In this study, soil samples were incubated for 28 days after a 28-day pre-incubation per iod. Pre-incubation and incubation were carried out at 20, 30, 40 and 50°C. To test the substrate availability effect on the temperature sensitivity of SR, glucose was added to soil at the beginning of the incubation period. Results showed that the highest pre-incubation temperature reduced the temperature sensitivity of SR during the subsequent incubation period. Glucose addition reduced the effect of high pre-incubation temperature on SR response. Thus, it appears that the observed decrease in SR sensitivity to temperature after one month pre-incubation at high temperature was due to a reduce in substrate availability and to a decrease in microbial biomass. Since the soil used in this study is a Calcari-Leptic Cambisol, a second experiment was also performed to determine the amount of CO2 from carbonates and the amount of CO2 from SOC. This study was carried out by measurements of the isotopic signatures (δ13C) of SOC, carbonates and emitted CO2. After 28 days of inc ubation, 23±9% of CO2 came from carbonates. This contribution was low compared to the high initial C-CaCO3 content in soil (4.3%), and it was independent to the incubation temperature. This study showed that reduce in the sensitivity of SR to high temperatures was probably due to a reduction in the substrate availability and to a decrease in microbial biomass.

Made available in DSpace on 2016-03-15T19:30:51Z (GMT). No. of bitstreams: 1 Rubens de Araujo Amaro.pdf: 1348722 bytes, checksum: 12b080e8bccba20a651d20c7fd52ff89 (MD5) Previous issue date: 2012-04-20 / Instituto Presbiteriano Mackenzie / The central objective of this study is to analyze how different conceptions of enterprise influence the development of the enterprising competency, taking as a reference the phenomenographic assumption that a single phenomenon is experienced in different ways by individuals. Generally, studies in this field treat competency as a set of attributes held by individuals and activated in real situations to resolve problems and take opportunities. They are based on a realist ontology, where subject and object are considered separate entities, and on an objectist epistemology, which presupposes that there is an objective meaning to all dimensions of the social world, waiting to be discovered by researchers. As a result, a set of individuals attributes that are independent of context are identified. These studies do not take into consideration the influence of the meanings that individuals attribute to their activities when developing their competency for enterprising. This gap is filled by this research, which is based on the idea that the different conceptions entrepreneurs have of their activities both form and organize the attributes put into play when these activities are performed. For this purpose, qualitative research using a methodology that is little known in organizational studies, phenomenography, was conducted. The main authors of this investigation approach are Ference Marton, Roger Säljö and John Bowden in the education area, and Gloria Dall Alba and Jörgen Sandberg in the competency area. This research was performed with twelve young entrepreneurs who participated in a pre-incubation program at a university located in the state of São Paulo. The data was collected based on two rounds of phenomenographic interviews held at the start and end of the program. Minutes from meetings between the students and the program advisors and with consultants from the junior company connected with the university were also used. The data was analyzed using phenomenographic techniques and the results point to the existence of three different ways of conceiving of enterprise within the group: (1) As an extension of a profession; (2) As an economic activity; (3) As an economic activity with a social impact. The evidence shows that these ways of experiencing enterprise lead to different strategies for learning and competency development. The evidence also shows that the individuals who had the deeper conceptions (2 and 3) developed their competency on more complex levels and obtained more success on the program, having their business projects evaluated and being invited to the incubation stage. After they participated in the program, their conceptions remained the same, which shows that learning occurred within the conception the individuals already possessed when they entered the program. This evidence helps to look at competency development in a new light. In order to develop professional competency it is necessary to go beyond the transmission of content required for good professional performance. It is fundamental to promote interventions that transform the conceptions individuals have of their activities. Individuals with deeper conceptions develop competencies on deeper levels. / O objetivo central desse estudo é analisar como as diferentes concepções de empreender influenciam o desenvolvimento da competência empreendedora, tomando-se como referência o pressuposto fenomenográfico de que um mesmo fenômeno é experienciado de diferentes maneiras pelos indivíduos. Em geral, os estudos nesse campo tratam a competência como um conjunto de atributos detidos pelos indivíduos e que são mobilizados em situações reais para solucionar problemas e aproveitar oportunidades. Partem de uma ontologia realista, em que sujeito e objeto são considerados entidades separadas, e de uma epistemologia objetista, que pressupõe haver um significado objetivo em todas as dimensões do mundo social à espera da descoberta pelos pesquisadores. Como resultado, identifica-se um conjunto de atributos individuais independentes do contexto. Esses estudos não levam em consideração a influência dos significados que os indivíduos atribuem às suas atividades no desenvolvimento de sua competência para empreender. Essa lacuna é preenchida por essa pesquisa, que toma como ponto de partida que as diferentes concepções que os empreendedores possuem de suas atividades tanto formam quanto organizam os atributos colocados em jogo para desempenhá-las. Para atingir esse propósito, foi conduzida uma pesquisa qualitativa utilizando uma metodologia pouco conhecida nos estudos organizacionais, a fenomenografia. Essa abordagem de investigação tem como principais autores Ference Marton, Roger Säljö e John Bowden na área de educação, e Gloria Dall Alba e Jörgen Sandberg na área da competência. Essa pesquisa foi realizada com doze jovens empreendedores participantes do programa de pré-incubação de uma universidade situada no Estado de São Paulo. Os dados foram coletados a partir de duas rodadas de entrevistas fenomenográficas realizadas no início e no final do programa. Foram utilizadas também as atas de reuniões desses jovens com os orientadores do programa e com consultores da empresa júnior ligada à universidade. Esses dados foram analisados utilizando-se técnicas fenomenográficas e os resultados apontam para a existência de três maneiras diferentes de conceber o empreender dentro do grupo: (1) Como uma extensão da profissão; (2) Como uma atividade econômica; (3) Como uma atividade econômica de impacto social. As evidências mostram que essas maneiras de experienciar o empreender dão forma a diferentes estratégias de aprendizagem e de desenvolvimento da competência. As evidências também mostram que os indivíduos que partilham das concepções mais profundas (2 e 3) desenvolveram sua competência em níveis mais complexos e obtiveram mais sucesso no programa, tendo seus projetos de negócio avaliados e convidados para a etapa de incubação. Após a participação no programa, as concepções permaneceram as mesmas, o que mostra que a aprendizagem se deu dentro da concepção que os indivíduos já possuíam quando entraram no programa. Essas evidências ajudam a lançar um novo olhar sobre o desenvolvimento de competências. Para desenvolver a competência profissional é preciso ir além da transmissão de conteúdos necessários ao bom desempenho profissional. É fundamental promover intervenções que transformem as concepções que os indivíduos possuem de suas atividades. Indivíduos com concepções mais profundas desenvolvem competências em níveis mais complexos.

Made available in DSpace on 2014-07-29T15:07:41Z (GMT). No. of bitstreams: 1 Eveline_Xavier.pdf: 537505 bytes, checksum: f46fc6f4fae888045c26180cb3ce26b0 (MD5) Previous issue date: 2008-08-05 / Mastitis is the most frequent disease in dairy cows, it causes great economic losses in herds and dairy industries and represents a hazard for public health. Among the etiologic agents identified, there is a predominance of bacteria species. However, several other groups of microorganisms may be present, one of those is a unicellular alga of the Prototheca genus, the Prototheca zopfii, an environmental agent of bovine mastitis. The infected cows usually have granulomatous changes in mammary tissue. Moreover microorganisms do not respond to routine therapy, resulting in the elimination of the infected animals. The main purposes of this study was to determine the occurrence of Prototheca zopfii on bulk tank milk in the state of Goiás and identify the limit of detection for Prototheca zopfii by two different approaches. We also wanted to know the samples pre-incubated with small concentration of Protoheca zopfii permits us to obtain positive growth in microbiological culture. We analyzed 473 samples from farms with high somatic cell count patterns but we did not detect Protoheca zopfii in any of those samples. The limit of sensitivity of the Prototheca zopfii was analyzed, in the approach of isolation the limit of detection was between 130 to 3,400 UFC/mL. In the approach of tally the limit was between 25 to 300 UFC/mL. It wasn t observed significant difference (p>0,05) between the approaches analyzed. However, significant statistical difference (p<0,05) occurred between the five types analyzed. After the pre-incubation at 37ºC/24h, the limit of sensibility was analyzed by the approach isolation, the limit was 30 UFC/mL, what means that the pre-incubation is so important to decrease the possibility of occurrence of false negative / Entre as enfermidades de grande preocupação para os bovinos leiteiros encontram-se as mastites, incluindo aquelas causadas por Prototheca spp., um agente ambiental, relacionado à mastite bovina que destaca-se pela gravidade das lesões que causam no tecido mamário e pela resistência a ações terapêuticas. Objetivou-se com o presente estudo determinar a ocorrência de Prototheca zopfii no leite cru refrigerado no estado de Goiás, identificar o limite de detecção deste patógeno pelos métodos de semeadura para isolamento, e semeadura para contagem e também verificar se a incubação de amostras de leite com baixo número de células da Prototheca zopfii permite a obtenção de resultados positivos na cultura microbiológica. Foram analisadas 473 amostras originárias de propriedades com histórico de elevada contagem de células somáticas e procedeu-se a avaliação do limite de sensibilidade para o agente por meio do método de semeadura para isolamento, cujo limite de detecção correspondeu à faixa de 130 a 3.400 UFC/mL. Quanto ao método de semeadura para contagem o limite estabelecido foi 25 a 300 UFC/mL. Portanto houve diferença estatística (p<0,05) entre os métodos analisados, porém, não houve diferença estatística (p>0,05) entre as cinco cepas analisadas. Após a incubação das amostras por 24 horas a 37ºC verificou-se que o limite de sensibilidade pelo método semeadura para isolamento diminui para 30 UFC/mL, diminuindo-se assim a possibilidade de ocorrência de falso negativo. Em nenhuma das amostras analisadas foi detectada a presença da Prototheca zopfi