Insetos são os organismos multicelulares mais bem-sucedidos no ecossistema terrestre e sua riqueza se deve, em parte, à simbiose com microrganismos. Geradora de diversidade fenotípica, a comunidade microbiana associada a insetos permite a manutenção de fenótipos complexos capazes de colonizar novos nichos e de se adaptar a fatores de estresse. A relevância da relação de simbiose na ordem Lepidoptera, todavia, tem sido questionada em função da alta variabilidade da comunidade bacteriana associada aos seus representantes. Tendo como modelo de estudo lagartas do gênero Spodoptera (Lepidoptera: Noctuidae), esse trabalho teve por objetivo melhor compreender a composição e diversidade da microbiota associada ao intestino de lepidópteros, assim como verificar o efeito da pressão de seleção direcionada à resistência na sua estrutura e capacidade de utilização de inseticidas como fonte de carbono. Para isso, foi realizada a análise metagenômica da comunidade microbiana intestinal de quatro espécies do gênero Spodoptera assim como de cinco populações naturais de S. frugiperda e de linhagens suscetível e resistentes desse inseto praga. Foram avaliadas linhagens de S. frugiperda resistentes aos inseticidas spinosad, chlorpyrifos, lambda-cyhalothrin, flubendiamide, teflubenzuron e à toxina de Bacillus thuringiensis Cry1A.105+Cry2Ab2. A análise da composição, riqueza e capacidade da comunidade bacteriana utilizar inseticidas foi baseada na determinação de índices de diversidade alfa e beta, no isolamento de bactérias intestinais em meio seletivo e na análise do potencial de crescimento dos isolados em inúmeros inseticidas. Nossos resultados indicam a importância da microbiota intestinal para esse gênero de Lepidoptera. Bactérias do gênero Enterococcus foram predominantes em todas as populações de Spodoptera analisadas, independentemente da espécie, dieta ou pressões de seleção às quais as lagartas foram expostas. Populações naturais de S. frugiperda apresentaram um microbioma mais diverso e com maior número de bactérias capazes de metabolizar inseticidas. A diversidade do microbioma, assim como a presença e capacidade de bactérias utilizarem inseticidas como fonte de carbono para o seu crescimento foram influenciadas pelo nível de exposição a tais compostos, demonstrando que, assim como o hospedeiro, a microbiota intestinal também se encontra em pressão de seleção direcionada a resistência. / Insects are the most successful multicellular organisms in the terrestrial ecosystem and their richness is partially due to symbiosis with microorganisms. The microbial community associated with insects allows the maintenance of complex phenotypes capable of colonizing new niches and adapting to stressors. The relevance of symbiosis in Lepidoptera, however, has been questioned due to the high variability of the bacterial community associated with its representatives. Using Spodoptera larvae as a model, this work aimed to better understand the composition and diversity of the gut microbiota associated with Lepidoptera, as well as to verify the effects of the selection pressure with insecticides in the microbial gut structure and the ability of members of the community to metabolize insecticides as carbon source. Thus, we performed a metagenomic analysis of the gut microbial community of four species of the genus Spodoptera (Lepidoptera: Noctuidae), as well as for five natural populations of S. frugiperda and susceptible and resistant strains of this pest. Strains of S. frugiperda resistant to the insecticides spinosad, chlorpyrifos, lambda-cyhalothrin, flubendiamide, teflubenzuron and Bacillus thuringiensis toxin Cry1A.105 + Cry2Ab2 were evaluated. The analysis of the composition, richness and ability of the bacterial community to metabolize insecticides were carried out through alpha and beta diversity indexes, isolation of intestinal bacteria in selective medium and analysis of the growth potential of isolates in multiple insecticides. Our data indicate the importance of symbiosis for S. frugiperda. Enterococcus prevailed in all populations analyzed, regardless of the species of Spodoptera, food source or selection pressure that the larvae were exposed. Microbial diversity and ability to metabolize insecticides were higher in natural populations exposed to a range of stressors in the field. The diversity of the gut microbial community associated to Spodoptera frugiperda, as well as the ability of its members to metabolize insecticides, were influenced by the degree of exposure to insecticides, showing that, like the host, the gut microbiota is also under selection pressure to resistance.

A fermentação de hidrolisados hemicelulósicos tem como principal dificuldade a presença de compostos inibidores ao metabolismo microbiano, derivados da degradação parcial da lignina, degradação dos açúcares e liberação de radicais acetil durante a etapa de hidrólise dos materiais lignocelulósicos. O presente trabalho teve por objetivo avaliar a influência de diferentes tratamentos de destoxificação sobre a composição e fermentabilidade do hidrolisado hemicelulósico de bagaço de cana-de-açúcar na produção de etanol e xilitol. Foram avaliados os seguintes tratamentos: a) alteração de pH com óxido de cálcio e ácido fosfórico seguido de adsorção com carvão ativo; b) utilização de resinas de troca iônica (A-860, A-500PS e C-150 - Amberlite); e c) extração líquido-líquido com interface imobilizada em membrana de fibra oca (Membrana, Charlote, NC - USA), na qual a fase orgânica foi uma mistura de octanol e Alamina 336 e a fase aquosa foi o próprio hidrolisado. De acordo com os resultados, os tratamentos aplicados (a, b e c) promoveram uma redução na concentração de ácido acético de 46,74%, 64,15% e 44,71% e uma redução na absorbância relativa (A.R.) de 82,0%, 94,59% e 46,07%, respectivamente. Na fermentação dos hidrolisados tratados, pela levedura Candida guilliermondii FTI 20037, após 48h de fermentação, os resultados para o fator de rendimento foram de 0,57g/g, 0,42g/g e 0,33 g/g após os tratamentos a, b e c, respectivamente. Quanto à produtividade volumétrica, na mesma ordem dos tratamentos foram obtidos os seguintes resultados: 0,39 g.L-1.h-1, 0,20 g.L-1.h-1 e 0,16 g.L-1.h-1. Nas fermentações dos hidrolisados tratados (a) e (b) pela levedura Pichia stipitis IMH 43.2, visando a produção de etanol, após 48h os resultados do fator de rendimento foram 0,38 g/g e 0,23 g/g, respectivamente, enquanto a produtividade volumétrica foi de 0,09 g.L-1.h-1 para o tratamento (a) e para o tratamento (b). Para o tratamento (c) não se observou a produção de etanol nas condições de fermentação utilizadas. Considerando os resultados obtidos, sugere-se que, para as condições experimentais empregadas, o hidrolisado seja tratado por alteração de pH seguido de tratamento com carvão ativado, uma vez que este tratamento resultou nos melhores resultados para o fator de rendimento tanto na produção de xilitol quanto na produção de etanol. / The fermentation of hemicellulosic hydrolysates has as main difficult the presence of compounds derived from partial degradation of lignin, sugars and release of acetyl groups, which are inhibitors of microbial metabolism, during the hydrolysis process of lignocellulosic materials. This study aimed to evaluate the influence of different detoxification treatments on the composition and fermentability of the sugarcane bagasse hemicellulosic hydrolyzate in the production of xylitol and ethanol. The following treatments were evaluated: a) change of pH with calcium oxide and phosphoric acid followed by adsorption with activated charcoal, b) use of ion exchange resins (A-860, A-500 PS and C-150 - Amberlite) and c) liquid-liquid extraction with immobilized interface in hollow-fiber membrane (Membrana, Charlote, NC - USA), in which the organic phase was a mixture of octanol and Alamine 336, and the aqueous phase was the hydrolyzate. According to the results, the employed treatments (a, b and c) promoted a reduction of 46.74%, 64.15% and 44.71% in the acetic acid concentration, and a reduction in the relative absorbance (RA) of 82.0%, 94,59% and 46.07% respectively. In the fermentation of the treated hydrolyzates by the Candida guilliermondii FTI 20037 yeast, aiming xylitol production, after 48h of fermentation, the results for xylitol yield were 0.57g/g, 0.42g/g and 0.33g/g, after the treatments a), b) and c), respectively. The volumetric productivity obtained was 0,39 g.L-1.h-1, 0,20 g.L-1.h-1 and 0,16 g.L-1.h-1, in the same order of treatments. In fermentation by Pichia stipitis IMH 43.2 of the hydrolyzates that used treatments (a) and (b), aiming the production of ethanol, after 48h, the results for yield were 0.38g/g and 0.23g/g, respectively, while the volumetric productivity was 0,09 g.L-1.h-1 for both treatments. For treatment (c) there was no ethanol production using the fermentation conditions applied in this work. Considering these results, it is suggested that for the experimental conditions used at this work, the hydrolyzate should be treated by pH change followed by treatment with activated charcoal, since this treatment resulted in better results of yield in the production of xylitol and ethanol.

Insecticide resistance is a global problem. Insecticide resistance management is very important, considering the time, effort, and cost of discovering and developing a new insecticide. There are diverse resistance mechanisms, but enhanced detoxification through overexpression of cytochrome P450s and target site insensitivity through mutation in insecticide binding site are the two most common mechanisms. The xenobiotic detoxification is divided into three successive phases (I, II and III), which ensures the metabolism and excretion of the detrimental toxins. Each phase comprises of a specific group of metabolizing enzymes such as P450s (phase I), GSTs (phase II) and ABC transporters (phase III). The major goal of my research was to understand the molecular mechanism of insecticide resistance in two economically important coleopteran pests, Leptinotarsa decemlineata and Tribolium castaneum. The transcriptional regulation of the P450 genes mediating insecticide resistance in L. decemlineata (imidacloprid-resistant) and T. castaneum (deltamethrin-resistant) were studied and the xenobiotic trans and cis-elements identified. RNA interference (RNAi), and reporter assays revealed that the cytochrome P450 genes involved in insecticide resistance are regulated by transcription factor Cap n Collar ‘CncC’ and muscle aponeurosis fibromatosis ‘Maf’ belonging to the b-ZIP transcription factor family. Site-directed mutagenesis was employed to identify the binding site for CncC and Maf. Sequencing of RNA isolated from CncC knockdown T. castaneum identified genes regulated by CncC and involved in insecticide detoxification. RNAi and insecticide bioassays confirmed the function of select phase II (glutathione-S-transferases) and phase III (ABC transporters) identified by RNA sequencing. Overall, these data revealed that the xenobiotic transcription factor CncC is the master regulator of multiple genes that are involved in insecticide resistance.

Smectite clay has been shown in studies over the past 20 years to sorb aflatoxin B1 (AfB1) in animal feed and thereby reduce its toxic influence on animals. In this study, 20 smectite samples were selected from industrial products or reference minerals. In the initial steps, it was shown that AfB1 entered the interlayer galleries of smectites and a 10-fold range in sorption ability was observed in a set of 20 smectite samples. Yet, it was not clear which clay properties (CEC, pH, base saturation) influenced this variation. In an effort to further explore properties that might influence the sorption of AfB1, three good sorbent samples were chosen from our set of 20 samples along with one sample of low sorption capacity. Those samples were fractionated into sand, silt, coarse clay (CC), and fine clay (FC) fractions. From all sample fractions, sorption isotherms and X-ray diffraction patterns were obtained. Additionally, a vermiculite and a palygorskite were examined with regard to sorption capacity. Concentration of smectite and their adsorption test suggest that differences in smectite composition are responsible for difference in sorption, not so much their relative abundance or other mineral phases. Initial infrared analysis indicates that weathered aluminous smectites, which have no octahedral iron or magnesium, belong to the poor AfB1 sorbents. Palygorskite and vermiculite are not effective sorbents. Based on the findings in this study, tentative quality criteria of sorbent selection for their use in animal feed were established. These criteria are: pH between 6.5 and 8.5, CEC > 75cmolc/kg, organic carbon < 2.5 g/kg, expression of XRD smectite peak and AlFeOHbending in FTIR and Langmuir adsorption capacity for AfB1 > 0.40 mol/kg.

Thesis (Ph. D.)--University of Hong Kong, 2009. / Includes bibliographical references (leaves 165-168). Also available online.

Diss. (sammanfattning). Uppsala : Sveriges lantbruksuniv., 2003. / Härtill 5 uppsatser.

Thesis (Ph. D.)--University of Hong Kong, 2009. / Includes bibliographical references (leaves 165-168). Also available in print.

Thèse (M.Ps.) -- Université du Québec à Chicoutimi, programme en extension de l'Université du Québec à Trois-Rivières, 2006. / "Mémoire présenté à l'Université du Québec à Chicoutimi comme exigence partielle de la maîtrise en psychologie offerte à l'Université du Québec à Chicoutimi en vertu d'un protocole d'entente avec l'Université du Québec à Trois-Rivières." Comprend des réf. bibliogr. : f. [213]-232. Document électronique également accessible en format PDF.

Made available in DSpace on 2014-06-11T19:24:41Z (GMT). No. of bitstreams: 0 Previous issue date: 2001-07Bitstream added on 2014-06-13T19:31:26Z : No. of bitstreams: 1 pantaroto_s_me_botfca.pdf: 713863 bytes, checksum: b770073600a204323c2ead910c060f71 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Durante o processamento de raízes de mandioca para a produção de farinha e fécula, são geradas grandes quantidades de resíduos, dentre os quais destacam-se a manipueira como água proveniente da prensa da massa de mandioca ralada para a produção de farinha ou água residual de fecularia, neste caso a manipueira diluída com água de extração. A linamarina é um b-glicosídeo de acetona cianidrina e etil-metil-cetona cianidrina, presente em todas as células da planta de mandioca. A clivagem deste glicosídeo, em decorrência da lise das paredes celulares da planta, dá início à cianogênese, ou seja, a produção de ácido cianídrico. A linamarina é solúvel em água, sendo carreada juntamente com os efluentes líquidos, gerando problemas tanto ambientais quanto econômicos, no que se refere à disposição final e aproveitamento dos mesmos como sub-produtos do processamento de mandioca. Na literatura há relatos sobre a habilidade de microrganismos a metabolizar a linamarina, como única fonte de carbono e energia. O presente estudo teve por objetivo o isolamento, seleção e identificação de microrganismos aeróbios, provenientes de amostras de manipueira e solo aos arredores de lagoas destinadas à decantação destes efluentes, avaliando-os quanto ao metabolismo de linamarina in vitro, visando o emprego das linhagens selecionadas em estudos futuros de biorremediação dos resíduos. Das amostras foram isoladas 118 culturas, das quais 66 caracterizaram-se como morfotipos bacterianos e 52 como leveduras. Dentre estes microrganismos, 31 morfotipos, sendo 26 bactérias e 5 por leveduras, escolhidos aleatoriamente, foram avaliados em meio mínimo contendo linamarina como única fonte de carbono e energia...( Resumo completo, clicar acesso eletrônico abaixo). / During the processing of cassava roots to produce flour and starch, residues are generated, where stand out the liquid effluents. The linamarin is a ß-glucoside of aceton cyanidrin and ethyl-methyl-ceton cyanidrin, it is present in all cassava plant. The cyanoglucoside broke begins the cyanogenese, thus producing cyanidric acid. The linamarin is soluble in water, and it is carried with the liquid effluents, and it generates ambiental and economics problems. The literature describe some microorganisms ability to metabolite linamarin. The present work aims the isolament, the selection and the identification of aerobies microorganisms from cassava liquid effluents and from adjacent soils samples of stabilization lagoons. Microbial cultures isolated have been available for linamarin in vitro metabolism. 118 strains are isolated, that 66 was characterized as bacteria and 52 as yeasts. 31 morfotypes were selected, choosed by chance, in minimum medium (MM), with linamarin as only carbon and energy source. Eight strains were selected ( seven bacterias and one yeast). The bacterias were identified by phylogenetic analyses, as three strains of Serratia marcescens, two strains of Bacillus, one strain of Acinetobacter johnnsonii, and one microbial culture of Proteobacteria group. The last one was not yet identified by literature. The yeast have been characterized by conventional taxonomy as Rhodotorulla glutinis...(Complete abstract, click electronic address below).

Made available in DSpace on 2014-10-09T12:49:20Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:02:35Z (GMT). No. of bitstreams: 1 09998.pdf: 7978978 bytes, checksum: 0d05419d6a29044ea66445399e3ae075 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP