Orientador: Anita Jocelyne Marsaioli / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-21T09:27:02Z (GMT). No. of bitstreams: 1 Araujo_FranciscaDianadaSilva_D.pdf: 5387746 bytes, checksum: ae8110c020cf470d09fb0e22f670508f (MD5) Previous issue date: 2012 / Resumo: Aspectos distintos da ecologia química de bactéria, fungo e abelha foram investigados e abordados em três capítulos. O primeiro capítulo descreve o estudo das moléculas sinalizadoras envolvidas no processo de quorum-sensing da bactéria Enterobacter sakazakii (Cronobacter spp.), que resultou na identificação de três acil-homosserina lactonas (acil-HSLs): (S)-(-)-N-heptanoil-HSL, (S)-(-)-N-dodecanoil-HSL e (S)-(-)-N-tetradecanoil-HSL. Estes semioquímicos foram degradados por enzimas de Bacillus cereus. No segundo capítulo o estudo do fungo Epicoccum nigrum possibilitou o isolamento de meleína, 4,5-dimetil-resorcinol, flavipina e de um novo metabólito, denominado epicolactona. O monitoramento destas substâncias em três mutantes de E. nigrum apontou para a produção de 5-hidroxi-meleína, ausente no fungo selvagem, indicando que a rota biossintética de policetídeos em E. nigrum foi alterada, ativando a ação de uma mono-oxigenase responsável pela oxidação da meleína. No terceiro capítulo, foram investigados feromônios produzidos por diferentes castas da abelha social Tetragonisca angustula. Bioensaios com as rainhas indicaram que lipídios cuticulares são possíveis responsáveis pela indução da cópula nos machos. Operárias fundadoras e guardas foram diferenciadas quimicamente por compostos presentes em seus extratos cefálicos e abdominais. Extratos cefálicos de machos em diferentes ciclos de vida mostraram-se semelhantes / Abstract: Different aspects of bacteria, fungus and bee chemical ecology were investigated and discussed in three chapters. First chapter describes the study of signaling molecules involved in the Enterobacter sakazakii (Cronobacter spp.) quorum sensing process that resulted in the identification of three acyl-homoserine lactones (acyl-HSLs): (S)-(-)-N-heptanoyl-HSL, (S)-(-)-N-dodecanoyl-HSL and (S)-(-)-N-tetradecanoyl-HSL. These semiochemicals were modified by Bacillus cereus enzymes. Second chapter describes the study of Epicoccum nigrum (fungus) revealing the isolation of mellein, 4,5-dimethylresorcinol, flavipin and of a novel metabolite, named epicolactone. Monitoring these compounds in three E. nigrum mutants pointed to the production of 5-hydroxymellein, absent in wild fungus strain, indicating that biosynthetic route of polyketides in E. nigrum has been modified, activating a monooxygenase responsible for mellein oxidation. Third chapter describes pheromones produced by different castes of Tetragonisca angustula social bee. Bioassays with queens indicated that cuticular lipids might be responsible for copulation induction in males. Cephalic and abdominal extracts of founded and guard workers were chemically different, while cephalic extracts of males at different life cycles were similar / Doutorado / Quimica Organica / Doutora em Ciências

Cronobacter species cause serious infections such as meningitis and enteritis in newborns and neonates, with the major vehicle being contaminated powdered infant formula. The main objectives of this study were i) to identify potential virulence factors, such as enterotoxin production; ii) characterize the gene(s) involved in adhesion and invasion of the human brain microvascular endothelial cells (HBMEC); and iii) determine whether strains from clinical, food, and environmental sources differ in their ability to produce surface-attached bacterial aggregates, known as biofilms. Random transposon mutagenesis was used on strains demonstrating the best adherence and invasion to blood- brain barrier cell lines (BBB). Isogenic mutants were then screened for increased or decreased adherence and invasion. Screening of the transposon library identified one isogenic mutant of a clinical strain which lost the ability to adhere to BBB cells. The transposon rescue revealed the insertion site to be within a diguanylate cyclase (DGC) gene. The major function of DGC in many Gram-negative bacteria is to synthesize cyclic diguanylate (c-di-GMP), a secondary bacterial metabolite known for regulating biofilm formation, motility, and virulence or aspects of microbial pathogenicity. Based on the findings of this study, DGC appears to play an important role in Cronobacter species’ ability to produce biofilms and may also have a role of the pathogenicity in the microorganism.

Cronobacter species cause serious infections such as meningitis and enteritis in newborns and neonates, with the major vehicle being contaminated powdered infant formula. The main objectives of this study were i) to identify potential virulence factors, such as enterotoxin production; ii) characterize the gene(s) involved in adhesion and invasion of the human brain microvascular endothelial cells (HBMEC); and iii) determine whether strains from clinical, food, and environmental sources differ in their ability to produce surface-attached bacterial aggregates, known as biofilms. Random transposon mutagenesis was used on strains demonstrating the best adherence and invasion to blood- brain barrier cell lines (BBB). Isogenic mutants were then screened for increased or decreased adherence and invasion. Screening of the transposon library identified one isogenic mutant of a clinical strain which lost the ability to adhere to BBB cells. The transposon rescue revealed the insertion site to be within a diguanylate cyclase (DGC) gene. The major function of DGC in many Gram-negative bacteria is to synthesize cyclic diguanylate (c-di-GMP), a secondary bacterial metabolite known for regulating biofilm formation, motility, and virulence or aspects of microbial pathogenicity. Based on the findings of this study, DGC appears to play an important role in Cronobacter species’ ability to produce biofilms and may also have a role of the pathogenicity in the microorganism.

Cronobacter species cause serious infections such as meningitis and enteritis in newborns and neonates, with the major vehicle being contaminated powdered infant formula. The main objectives of this study were i) to identify potential virulence factors, such as enterotoxin production; ii) characterize the gene(s) involved in adhesion and invasion of the human brain microvascular endothelial cells (HBMEC); and iii) determine whether strains from clinical, food, and environmental sources differ in their ability to produce surface-attached bacterial aggregates, known as biofilms. Random transposon mutagenesis was used on strains demonstrating the best adherence and invasion to blood- brain barrier cell lines (BBB). Isogenic mutants were then screened for increased or decreased adherence and invasion. Screening of the transposon library identified one isogenic mutant of a clinical strain which lost the ability to adhere to BBB cells. The transposon rescue revealed the insertion site to be within a diguanylate cyclase (DGC) gene. The major function of DGC in many Gram-negative bacteria is to synthesize cyclic diguanylate (c-di-GMP), a secondary bacterial metabolite known for regulating biofilm formation, motility, and virulence or aspects of microbial pathogenicity. Based on the findings of this study, DGC appears to play an important role in Cronobacter species’ ability to produce biofilms and may also have a role of the pathogenicity in the microorganism.