Orientadores: Ângela Maria Moraes, Pedro de Oliva Neto / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-19T16:03:17Z (GMT). No. of bitstreams: 1 Bellini_MarciaZilioli_D.pdf: 4612824 bytes, checksum: f18ee0cbf9ffaa3cdc4eb23a70825113 (MD5) Previous issue date: 2012 / Resumo: Materiais poliméricos são frequentemente utilizados na engenharia de tecidos como cobertura ou suporte para o crescimento celular, permitindo a adesão, o crescimento e a manutenção da função das células neles cultivadas, de forma a viabilizar o desenvolvimento e/ou a cicatrização de tecidos como a pele. Dentre os requisitos para a seleção destes materiais destacam-se propriedades como biocompatibilidade, tamanho e formato de poros, comportamento na presença de fluidos biológicos, assim como as próprias características do tecido a ser regenerado. Este trabalho visou ao desenvolvimento e à avaliação do uso de membranas constituídas de complexos polieletrólitos obtidos com os polímeros xantana e quitosana como curativos dérmicos e suportes de adesão e crescimento de células-tronco mesenquimais (CTMs). Para tal, amostras lamelares e porosas foram preparadas e caracterizadas quanto à morfologia, espessura, comportamento em soluções aquosas e resistência mecânica, assim como quanto à citotoxicidade direta e indireta a células L929. Testes de adesão e proliferação de CTMs sobre o biomaterial também foram realizados. Os resultados obtidos mostram que diferentes proporções poliméricas, a inclusão ou não da etapa de desaeração e a adição de tensoativos resultam em materiais com distintas características. Membranas com maior concentração de xantana mostram-se instáveis frente à exposição por longos períodos a meio de cultivo celular, enquanto que membranas com proporção polimérica equivalente sem adição de surfatantes e desaeradas tendem a ser finas e transparentes, apresentando elevada capacidade de absorção de água (85,57g/g) e de fluido corpóreo simulado (15,78g/g), com perda de massa máxima de 17% quando expostas por 144h a meio de cultura de células animais. Tais membranas não são citotóxicas a células L929 e apresentam adequada estrutura para adesão e proliferação de CTMs, revelando-se ideais para o uso como curativos dérmicos bioativos. A adição de Pluronic F68 durante a preparação das amostras de igual proporção polimérica possibilitou a obtenção de membranas porosas e espessas, com características favoráveis para a aplicação como suportes para engenharia de tecidos, como a presença de poros interconectados e distribuídos de forma homogênea pela estrutura, baixa toxicidade in vitro, espessura de 1,84 mm, elevada absorção de fluidos fisiológicos (17,99g/g) e de meio de cultivo celular (8,58g/g) e perda de massa em meio de cultivo de 33% em 144 horas, além de adequada estrutura para adesão e proliferação de CTMs / Abstract: Polymeric materials are frequently used in tissue engineering as dressings or scaffolds, allowing the adhesion, growth and maintenance of function of the cells cultured on their surfaces, in order to facilitate the development and / or healing of tissues such as skin. The requirements for the selection of these materials include properties such as biocompatibility, pore size and shape, behavior in the presence of biological fluids, as well as the actual characteristics of the tissue to be regenerated. This work aimed to develop and evaluate the use of membranes formed by polyelectrolyte complexes obtained from the polymers xanthan and chitosan as dermal dressings and supports for the attachment and growth of mesenchymal stem cells (MSCs). Lamellar and porous samples were prepared and characterized according to morphology, thickness, behavior in aqueous solutions and mechanical strength, as well as direct and indirect cytotoxicity to L929 cells. Tests of adhesion and proliferation of MSCs on the obtained biomaterial were also performed. The results show that different polymer ratios, the inclusion or not of a deaeration step and the addition of surfactants result in materials with different characteristics. Membranes with high proportions of xanthan were not stable for long periods of exposure to animal cell culture medium, while membranes with equivalent polymeric proportion, degassed and not prepared in the presence of surfactants tended to be thin and transparent, presenting high absorption capacity of water (85.57 g/g) and simulated body fluid (15.78 g/g) and mass loss of up to 17% when exposed for 144h to animal cells culture medium. Those membranes were not cytotoxic to L929 cells and provided adequate structure for adhesion and proliferation of MSCs, showing characteristics suitable for use as dressings for skin lesions. The addition of Pluronic F68 during the preparation of samples of equal proportion of xanthan and chitosan resulted in thick porous membranes, with favorable characteristics for application as scaffolds for tissue engineering, such as the presence of homogeneously distributed interconnected pores, low toxicity in vitro, thickness of 1.84 mm, high absorption of physiological fluids (17.99 g/g) and cell culture medium (8.58 g/g), mass loss in culture medium of 33% after 144 hours, and adequate structure for adhesion and proliferation of MSCs / Doutorado / Desenvolvimento de Processos Biotecnologicos / Doutor em Engenharia Química

Orientadores: Florencia Cecilia Menegalli, Rosiane Lopes da Cunha / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-14T14:28:38Z (GMT). No. of bitstreams: 1 CiroVelasquez_HectorJose_D.pdf: 3600504 bytes, checksum: efd0571f00b5ea398f5836590f0165bb (MD5) Previous issue date: 2009 / Resumo: Suspensões de gomas xantana e de l-carragena foram secas usando um secador de leito de jorro fluidizado com partículas inertes de vidro e plásticas de ABS (acrylonitrile butadine styrene). O processo de secagem foi avaliado quanto ao desempenho do secador (eficiência de produção de pó e retenção de sólidos), características fluidodinâmicas (velocidades da partícula inerte no jorro e ânulo, queda de pressão no leito, largura da fonte, altura máxima de jorro, distribuição de temperaturas no leito) e qualidade do produto final obtido (propriedades reológicas e teor de umidade). Um planejamento fatorial 23 com 2 pontos centrais e 6 pontos axiais e superfícies de resposta foi usado para determinar o efeito das condições de secagem (temperatura de ar, vazão de suspensão e vazão de ar no jorro e ânulo) sobre o processo e na qualidade do produto final. Os resultados mostraram que foi possível obter produto reconstituído de pó de xantana usando vidro ou ABS como inerte. No entanto, para suspensões de l- carragena não foi possível a secagem com partículas esféricas de vidro devido à alta tensão superficial e baixo ângulo de contato. De acordo com os resultados do planejamento experimental, a eficiência de produção média de pó de goma xantana usando vidro como inerte foi de 28% com uma retenção de sólidos de 65%, enquanto que usando ABS a produção média foi de 45% e a retenção de sólidos de 49%, ou seja, o melhor desempenho do secador ocorreu quando ABS foi empregado como partícula inerte. Para a secagem de suspensões de l-carragena com partículas de ABS a eficiência de produção média de pó foi de 23% e a retenção media foi de 71%. A variável mais relevante na secagem das suspensões de gomas xantana e carragena foi a vazão de suspensão, sendo que um aumento desta variável produziu um baixo rendimento de pó e aumentou a retenção de sólidos dentro do leito. A queda de pressão do leito apresentou uma variação periódica indicando uma instabilidade fluidodinâmica. A distribuição de temperatura no leito mostrou uma operação quase isotérmica e que o processo evaporativo ocorreu principalmente na zona do jorro e base do ânulo. A velocidade da partícula no jorro foi dependente da vazão de ar na região do jorro, enquanto que a velocidade da partícula dentro no ânulo foi função da vazão de suspensão e também da vazão de ar que passava pelo jorro. A xantana obtida pela secagem em jorro fluidizado formou suspensões de natureza altamente pseudoplástica e com propriedades viscoelásticas de gel fraco. A vazão de alimentação da suspensão (=1 g/min) foi um fator importante para a preservação da qualidade reológica. A secagem de suspensões de goma xantana realizada em condições ótimas, tanto em leitos com partículas de ABS quanto de vidro, não mostrou efeito na qualidade reológica do produto. O produto reconstituído de l-carragena obtido nas condições otimizadas de secagem também formou suspensões de natureza altamente pseudoplástica, porém com propriedades viscoelásticas características de suspensões altamente diluídas (G''>G'), mostrando valores de viscosidade, módulos elástico (G') e de perda (G'') menores que o produto comercial e portanto uma perda de qualidade do produto. Nas condições de melhor desempenho do secador, as suspensões de l-carragena foram mais susceptíveis a sofrer mudanças em sua estrutura molecular que a goma xantana / Abstract: Xanthan and l-carrageenan suspensions were dried using a two dimensional spouted fluidized bed dryer with inert particles of glass and ABS (acrylonitrile butadine styrene).The dryer performance (powder production and solid retention), fluid flow characteristics (particle velocity in the spout and annulus, pressure drop, fountain width, maximum spout height, distribution of temperatures inside the bed) and quality properties of final product (rheological properties and moisture content) were evaluated. A complete 23 factorial design with 2 central points and 6 axial points together with response surfaces analysis was used to determine the effect of the drying conditions (drying temperature, suspension mass flow and air flow in the spout and annulus) on the drying process and final product. The results showed that it is possible obtain a reconstituted powder of xanthan gum using glass and ABS as inert particles. However, for suspensions of l- carrageenan was not possible the drying with glass spherical particles due to high superficial tension (low angle of contact). According to results of experimental design the mean powder production of xanthan gum using glass as inert was of 28% with a solid retention of 65%, whereas using ABS the mean powder production was of 45% with a solid retention of 49%, thus the best performance of the drier occurs when the bed with ABS is operated. In addition, the drying of l carrageenan suspensions with ABS particles showed a me n production of 23% with a solids retention of 71%. The most significant variable in the drying of the suspensions of xanthan and l carragena gum was the suspension mass flow rate where an increases produces a diminishing of the powder production increasing the solids retention in the bed. The pressure drop in the bed presented a periodic variation with the processing time indicating a hydrodynamics instability. The temperature distribution in the bed showed that annulus zone operated almost isothermally and that the spout zone and the annulus base are the zones where occurs the evaporative process. The particle velocity in the spout depends upon of the air flow in the spout, whereas the particle velocity in the annulus is function of the aeration and suspension mass flow rate. The reconstituted xanthan powder produced suspensions of highly pseudoplastic nature and with viscoelastic weak gel properties. The suspension mass flow rate (=1 g/min) was a factor important to preserve its rheological quality. To xanthan gum the drying operating conditions evaluated in the optimum point showed that the inert particle (ABS and glass) not influenced on the rheological quality of the reconstituted product. The l-carrageenan suspensions evaluated in the drying optimum conditions formed suspensions of highly pseudoplastic nature with viscoelastic properties of suspensions highly diluted (G''>G'). Also, the rheological and viscoelastic characteristics as viscosity, storage (G') and loss moduli (G'') are lower than commercial gum indicating a severe loss of product quality. In the conditions of better performance of the dryer, the suspensions of l- carrageenan were more sensitive to suffer changes in its molecular structure than the xanthan gum / Doutorado / Doutor em Engenharia de Alimentos

This thesis reports the development of a novel drug delivery system consisting of hollow nanoparticles, formed from manganese dioxide (δ-MnO2) sheets, that are coated with polydopamine and folic acid to selectively target cancer cells. The biodegradability and colloidal stability of the uncoated hollow nanoparticles were investigated in comparison to solid MnO2 nanoparticles and graphene oxide sheets. The MnO2 hollow nanoparticles degraded at a faster rate and seem to have a higher surface area and better colloidal dispersion than solid MnO2 nanoparticles. Xanthan gum was proven to improve colloidal dispersion of these hollow nanoparticles and were used for further cell studies. In this study, cancer and healthy cells were treated with coated hollow nanoparticles, and results indicate that this novel hollow nanoparticle may preferentially target and kill cancer cells. Particle aggregation has shown to be toxic to cells. Further studies with this novel drug delivery system may lead to a groundbreaking solution to targeted cancer therapy. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2020. / FAU Electronic Theses and Dissertations Collection

This study examined the effects of guar gum and xanthan gum on flax supplemented breads through objective and sensory testing. Breads containing flaxseed and gums were found to have a significantly (p<0.05) higher water activity than the control bread. Control bread was also found to have a higher (p<0.05) volume while flax breads containing guar gum had a significant (p<0.05) decrease in volume. Control bread and bread containing guar gum were significantly (p<0.05) harder in crumb texture. Breads with flax and xanthan gum displayed a significant (p<0.05) amount of springiness. While there was no significant (p>0.05) difference in peroxide values among bread samples, control bread had a lower (p<0.05) anisidine value indicating a decrease in hydroperoxide breakdown. While not significant (p>0.05), bread containing xanthan gum had a lower anisidine value than the other treatments. Sensory analysis found bread with both gums to be moister (p<0.05) and have a strong (p<0.05) yeasty aroma and fresher flavor. Control bread was found to have the least (p<0.05) yeasty aroma and taste significantly (p<0.05) less bitter but more stale. / Master of Science

A busca por embalagens flexíveis rapidamente degradáveis tem sido intensa nos anos mais recentes. Amidos de variadas fontes têm sido avaliados para a produção de filmes, sendo que a maioria destes apresenta boas características mecânicas e de barreira ao oxigênio, entretanto, uma série de limitações é observada com relação às suas características hidrofílicas e permeabilidade ao vapor d´água. O amido de ervilha normalmente apresenta teores mais elevados de amilose, o que pode melhorar a obtenção da rede formadora de filmes. Além disto, as associações amido-goma podem modificar a gelatinização e retrogradação do amido, processos que interferem na formação de filmes. O acréscimo de plastificantes também tem se mostrado de importância para melhorar as propriedades mecânicas dos filmes. Assim, o objetivo do presente trabalho foi avaliar o efeito da adição de goma xantana e de glicerol ao amido de ervilha verde de alto teor de amilose (cv. Utrillo) na elaboração de filmes e em suas características. Soluções filmogênicas (SF) com diferentes teores de amido de ervilha (3, 4 e 5%), de goma xantana (0, 0,05 e 0,1%) e de glicerol (proporção glicerol-amido de 1:5 p/p) foram estudadas. As SF foram obtidas por ebulição (5 min.), seguida de autoclavagem por 1h. a 120°C. Os filmes foram prepa rados segundo a técnica de casting. O aumento da concentração de amido na solução filmogênica aumentou a espessura, fator de ruptura, resistência à perfuração e solubilidade dos filmes em água. O aumento da concentração da goma xantana interferiu apenas nas propriedades associadas à cor dos filmes, aumentando os valores da tonalidade e decrescendo o croma a* e a transparência. O aumento da concentração do glicerol interferiu nas propriedades mecânicas dos filmes, gerando redução dos valores de resistência máxima à tração, tensão na ruptura, resistência à perfuração e fator de ruptura. O plastificante também gerou aumento do alongamento na ruptura, redução da transparência e aumento da espessura e da solubilidade do filme em água. / In the past few years, the attempt to obtain degradable flexible packaging has increased considerably. In this sense, starches obtained from different botanical sources have been evaluated to produce films. Most of these films present good mechanical characteristics and provide a good barrier to oxygen. Nevertheless, some limitations have been observed in relation to their hydrophilic properties and permeability to water vapor. Studies using starch from green peas with high levels of amylose to produce films were not found in the literature. The higher levels of amylose can improve the achievement of the matrix that forms films. In addition, starch-gum associations can modify starch gelatinization and retrogradation, processes which interfere with film formation. The addition of plasticizers has also been considered important to improve the mechanical properties of films. The aim of this study was to evaluate the effect of the addition of xanthan gum and glycerol to the starch of green peas with high content of amylose (cv. Utrillo) in the preparation of films and in their features. Filmogenic solution (FS) with different levels of pea starch (3, 4 and 5%), xanthan gum (0, 0.05 and 0.1%) and glycerol (glycerol-starch ratio of 1:5 p/p) were tested. The FS was obtained by boiling (5 min.), followed by autoclaving for 1h. at 120°C. The films were prepared by casting. The increased concentration of starch in the solution increased the thickness, factor of rupture, puncture force and solubility of films in water. Increasing amounts of xanthan affected only the properties associated with the color of the films, increasing the values of hue angle and decreasing the chroma a* and transparency. The increased concentration of glycerol interfered in the mechanical properties of the films, causing reduction of the maximum values of tensile strength, strain at break, puncture force and factor of rupture. The plasticizer also caused an increase of elongation at break, reduced transparency and increased thickness of the film and the solubility in water.

With the production from mature oil fields declining, the increasing demand of oil urges towards more effective recovery of the available resources. Currently, the CO2 Floods are the second most applied EOR processes in the world behind steam injection. With more than 30 years of experience gained from CO2 flooding, successful projects have showed incremental oil recovery ranging from 7 to 15 % of the oil initially in place. Despite all of the anticipated success of CO2 floods, its viscosity nature is in heterogeneous and naturally fractured reservoirs is challenging; CO2 will flow preferentially through the easiest paths resulting in early breakthrough and extraction ineffectiveness leaving zones of oil intact. This research aims at investigating gel treatments and viscosified water-alternating-gas CO2 mobility control techniques. A set of experiments have been conducted to verify the effectiveness and practicality of the proposed mobility control approaches. Our research employed an imaging technique integrating an X-Ray CT scanner with a CT friendly aluminum coreflood cell. With the integrated systems, we were able to obtain real time images when processed provide qualitative and qualitative evaluations to the coreflood. The research studies included preliminary studies of CO2 and water injection performance in fractured and unfractured cores. These experiments provided a base performance to which the performances of the mobility control attempts were compared. We have applied the same methodology in evaluation of the experimental results to both conformance control gel treatments and viscosified water-alternating-gas CO2 mobility control. The gel conformance control studies showed encouraging results in minimizing the effect of heterogeneities directing the injected CO2 to extract more oil from the low permeability zones; the gel strength was evaluated in terms of breakdown and leakoff utilizing the production data aided with CT imaging analysis. The viscosified water coupled with CO2 investigations showed great promising results proving the superiority over neat CO2 injection. This research serves as a preliminary understanding to the applicability of tested mobility control approaches providing a base to future studies in this category of research.

This thesis addresses the application of xanthan/borate gel for lost circulation treatment. Steady shear viscometry method was applied in which the gel system was under constant shear rate while apparent viscosity was being recorded. The apparent viscosity was constant up to initial gelation time in which viscosity started to build up. Four parameters: initial and final gelation times as well as initial and final viscosities are defined and a correlation is derived between those parameters and four variables: polymer blended with crosslinker, pH-controller, and magnesium chloride concentration as well as temperature. These correlations can help the drilling industry to manage the lost circulation treatment job in a way to have enough time and pressure to pump the fluid and to optimize the time and quality required for final gel. The effects of those variables besides mixing time and shear history on gelation were also investigated. Temperature and pH-controller shortens initiation of gelation. Poly-cross shifts viscosity upward. Retarder postpones the final gelation time. Shear history does not affect initial gelation time and increase of mixing time reduces initial gelation time. This thesis also investigates the rheological model behavior of this gel system before initial gelation time which is the time allowed for pumping the fluid. Shear stress was measured at 0.1,1,50, and 450 rpm besides the conventional readings. Then residual mean squares for six common rheological models were obtained. Sisko was found to be the best fitting model based on this statistical approach. Moreover a modified Bingham-plastic and low shear yield point model are suggested.

abstract: It is estimated that wind induced soil transports more than 500 x 106 metric tons of fugitive dust annually. Soil erosion has negative effects on human health, the productivity of farms, and the quality of surface waters. A variety of different polymer stabilizers are available on the market for fugitive dust control. Most of these polymer stabilizers are expensive synthetic polymer products. Their adverse effects and expense usually limits their use. Biopolymers provide a potential alternative to synthetic polymers. They can provide dust abatement by encapsulating soil particles and creating a binding network throughout the treated area. This research into the effectiveness of biopolymers for fugitive dust control involved three phases. Phase I included proof of concept tests. Phase II included carrying out the tests in a wind tunnel. Phase III consisted of conducting the experiments in the field. Proof of concept tests showed that biopolymers have the potential to reduce soil erosion and fugitive dust transport. Wind tunnel tests on two candidate biopolymers, xanthan and chitosan, showed that there is a proportional relationship between biopolymer application rates and threshold wind velocities. The wind tunnel tests also showed that xanthan gum is more successful in the field than chitosan. The field tests showed that xanthan gum was effective at controlling soil erosion. However, the chitosan field data was inconsistent with the xanthan data and field data on bare soil. / Dissertation/Thesis / Ph.D. Civil and Environmental Engineering 2011

Submitted by THAÍSA ZANETONI MARTINS null (thaisa_martins00@hotmail.com) on 2016-05-02T21:00:40Z No. of bitstreams: 1 Dissertação completa e corrigida em pdf.pdf: 3120972 bytes, checksum: 2a88d2765e9af6b31401eaf64047de8a (MD5) / Approved for entry into archive by Felipe Augusto Arakaki (arakaki@reitoria.unesp.br) on 2016-05-04T19:30:40Z (GMT) No. of bitstreams: 1 martins_tz_me_jabo.pdf: 3120972 bytes, checksum: 2a88d2765e9af6b31401eaf64047de8a (MD5) / Made available in DSpace on 2016-05-04T19:30:40Z (GMT). No. of bitstreams: 1 martins_tz_me_jabo.pdf: 3120972 bytes, checksum: 2a88d2765e9af6b31401eaf64047de8a (MD5) Previous issue date: 2016-04-04 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O cancro cítrico tem como agente causal a bactéria Xanthomonas citri subsp. citri (Xac), que afeta diferentes espécies de citros economicamente importantes. É uma doença ainda sem método curativo, e pela sua relevância e dano econômico, faz-se necessário o entendimento em termos moleculares da interação Xac-citros para o desenvolvimento de estratégias que controlem a doença. O objetivo do presente trabalho foi investigar os efeitos da deleção da ORF XAC0024 presente no genoma da Xac isolado 306, que codifica uma proteína hipotética conservada e que apresenta vários domínios putativos, entre eles o domínio peptidase M23. A hipótese é que esta proteína pode estar envolvida com a patogenicidade e/ou virulência da bactéria. Para obter o mutante ΔXAC0024 foi utilizada a técnica de mutagênese sítio-dirigida, seguida de recombinação homóloga com o vetor suicida pOK1. O mutante ΔXAC0024 foi analisado em relação às características de patogenicidade, crescimento in vivo e in vitro, capacidade de autoagregação, produção de biofilme e produção de goma xantana. O teste de patogenicidade e a curva de crescimento in vivo foram realizados em limão cravo utilizando o método de infiltração por seringa para a inoculação da bactéria. Os sintomas do desenvolvimento da doença foram registrados por fotografia digital até o 25º dia após a inoculação (dai) e a curva de crescimento in vivo também foi determinada até o 25º dai. A curva de crescimento in vitro e a agregação célula-a-célula foram analisadas em meio de cultura líquido NB. O ensaio de produção de biofilme foi feito em meio de cultura líquido XVM2 em superfície abiótica empregando cristal violeta para sua visualização e espectrofotometria para sua quantificação. A extração da goma xantana foi realizada por meio da precipitação com isopropanol após dissolução de KCl em meio goma com as bactérias multiplicadas em 96 horas. Verificou-se que o mutante ΔXAC0024 foi menos virulento em relação à Xac selvagem e que o seu desenvolvimento in planta é limitado; porém, em meio nutritivo NB apresenta crescimento similar à Xac selvagem. O mutante ΔXAC0024 apresentou ainda maior formação de goma xantana, diminuição na capacidade de se autoagregar e inalterabilidade na formação de biofilme em relação à Xac selvagem. Essa é a primeira evidência de que a ORF XAC0024 interfere na virulência da bactéria, afeta a produção de goma xantana e a agregação celular de Xac 306. A hipótese é de que a proteína codificada pela ORF XAC0024 participe do sistema de degradação do peptideoglicano na divisão celular em Xac, sendo que experimentos adicionais são necessários para confirmar esta hipótese. / The bacteria Xanthomonas citri subsp. citri (Xac) is the causal agent of citrus canker, a disease that affects different species of economically important citrus. There is no a curative method for this disease, and do to its relevance and economic damage, it is necessary to understand at molecular level the Xac-citrus interaction in order to develop strategies to control the disease. The objective of this study was to investigate the effects of the deletion of the ORF XAC0024 present in the genome of Xac strain 306, which encodes a conserved hypothetical protein and has several putative domains, including peptidase M23 domain. It is hypothesized that this protein may be involved in the pathogenicity and / or virulence of the bacterium. For the ΔXAC0024 mutant was used for site-directed mutagenesis technique, followed by homologous recombination with the suicide vector pOK1. The ΔXAC0024 mutant was analyzed in relation to pathogenicity characteristics, growth in vivo and in vitro, self-aggregation capacity, biofilm production and production of xanthan gum. The pathogenicity test and in vivo growth curves were performed on Rangpur lime using syringe-infiltration method for the inoculation of bacteria. Symptoms of the disease development were recorded by digital photography to the 25° day after inoculation (dai) and in vivo growth curve was also determined to give the 25°. The growth curve in vitro and cell-to-cell aggregation were analyzed in liquid culture medium NB. Biofilm production test was done in a liquid culture medium XVM2 on abiotic surface using crystal violet for your viewing and spectrophotometry for its quantification. The extraction of xanthan gum was performed by isopropanol precipitation after dissolving KCl among gum with bacteria grown in 96 hours. It was found that the ΔXAC0024 mutant was less virulent compared to the wild Xac and its development in planta is limited; however, in nutrient medium NB presents similar growth to the wild Xac. The ΔXAC0024 mutant also showed increased formation of xanthan gum, decreased ability to self-aggregation and inviolability in biofilm formation compared to wild Xac. This is the first evidence that ORF XAC0024 interfere with bacterial virulence affects the production of xanthan gum and cell aggregation Xac 306. The hypothesis is that the protein encoded by ORF XAC0024 participate in the peptidoglycan degradation in division system cell in Xac, and further experiments are needed to confirm this hypothesis.

Made available in DSpace on 2014-06-11T19:27:21Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-03-20Bitstream added on 2014-06-13T20:35:45Z : No. of bitstreams: 1 pigatto_g_me_sjrp.pdf: 376138 bytes, checksum: 0d3df3ba13a94adf6610c9416261a91c (MD5) / Xanthomonas campestris é uma bactéria fitopatogênica que causa a podridão negra no sistema vascular das plantas da família das cruciferaceaes. Produz um exopolissacarídeo denominado goma xantana, que possui propriedades reológicas únicas sendo utilizada amplamente como agente de suspensão, espessante, emulsionante e estabilizante. É aplicados em indústrias petrolíferas, alimentícias, farmacêuticas, mineração, têxtil, termoquímicas, tintas, cosméticos e produtos agropecuários. O Brasil é um grande produtor mundial de cana de açúcar e álcool etílico. Produtos estes utilizados para a produção de xantana; o primeiro como substrato da fermentação e o segundo para a separação da goma. Apesar de todo esse potencial, o Brasil importa grande quantidade de goma xantana que poderá ser produzida com grande competitividade internacional. Portanto, este trabalho objetivou a utilização da técnica de irradiação ultravioleta, em uma linhagem específica de Xanthomonas campestris, para a obtenção de mutantes estáveis que possam melhorar o rendimento e/ou qualidade de goma obtida. A quantificação foi realizada através da determinação da biomassa, viscosidade, cálculos do rendimento da biomassa e goma. A irradiação UV por 600 segundos causou uma redução de 92,2% na população irradiada e as linhagens sobreviventes foram isoladas e analisadas nos testes de produção e viscosidade da goma xantana. As linhagens I6, I7, I9 e I10 apresentaram um aumento de 102% na produção de goma comparando com a linhagem não irradiada. Em relação à viscosidade do caldo, as linhagens irradiadas obtiveram um aumento de 48% comparadas com as não irradiadas de 20 e 30 rpm. A viscosidade da solução de goma xantana 1%, também foram superiores quando comparadas com a não irradiada. O aumento de... / Xanthomonas campestris is fitopatogenic bacterium that causes the black rotten in the vascular system of the plants of the family of the cruciferaceaes. It produces an exopolysaccharides that forms the xanthan gum, which is used in ample variety as agent of suspension, thicker, emulsifier and stabilizing, and singular rheological properties. It is applied in petroliferous, nourishing, pharmaceutical industries, of mining, textile, thermo chemistries, inks, cosmetics and farming products. Brazil is the worldwide producing greater of sugar cane of sugar and ethyl alcohol. Products theses used for the xanthan production; the first one as substratum of the fermentation, and the second as for the separation of the gum. Despite all this potential, the Brazil imports lot of xanthan gum that could be produced with great international competitiveness. This aimming work the used of the ultraviolet technique of irradiation in a specific strain of Xanthomonas campestris to obtain the mutants that can improve the income and/or quality of produced gum, through the determination of the biomass, viscosity, calculations of the income of the biomass and gum. The UV irradiation during 60 seconds caused a reduce of the 92.2% in the irradiated strains and the survived strains were isolated and analysed in the tests of production and viscosity of xanthan gum. The strains I6, I7, I9 e I10 showed increased in the xanthan production of 102% comparing with the non-irradiated strain. In relation the viscosity of the broth the irradiated strains the increase of 48% in shear rate of 20 and 30 rpm compared with the no irrdiated. The viscosity of the xanthan solution 1% irradiated were higher also whwn compared with no irradiated in both shear rate (20 and 30 rpm. The increase of viscosity was of 17% to rotational speed of 20 rpm and 16% to 30 rpm. The ...(Complete abstract click electronic access below)