Free-living amoebae (FLA) are protists of ubiquitous distribution characterised by their changing morphology and their crawling movements. They have no common phylogenetic origin but can be found in most protist evolutionary branches. Acanthamoeba is a common FLA that can be found worldwide and is capable of infecting humans. The main disease is a life altering infection of the cornea named Acanthamoeba keratitis. Additionally, Acanthamoeba has a close relationship to bacteria. Acanthamoeba feeds on bacteria. At the same time, some bacteria have adapted to survive inside Acanthamoeba and use it as transport or protection to increase survival. When conditions are adverse, Acanthamoeba is capable of differentiating into a protective cyst. This study had three objectives. First, isolate and identify new FLA and Acanthamoeba strains. Second, identify encystation factors of Acanthamoeba. Third, identify and characterise new potential antimicrobial proteins produced by Acanthamoeba. The isolation of environmental amoebae was performed, and several strains of Acanthamoeba were identified from previously known genotypes. Also, two new species of FLA were identified: Allovahlkampfia minuta and Leptomyxa valladaresi. The dynamics of encystment were studied in different strains of Acanthamoeba. RNAseq was used to study gene expression during differentiation and identify differentially expressed genes. We identified different encystment factors including at least two encystment related proteases. A new antimicrobial zymogram was developed that identified antimicrobial proteins being secreted by Acanthamoeba. A 33 kDa protease was found to be able to lyse bacteria. We created DNA constructs encoding the protease and a lysozyme from Acanthamoeba for heterologous expression. The genes were successfully cloned. However, bacteria were not able to produce the proteins most probably due to their antimicrobial characteristics. Further studies are required regarding encystment and antimicrobial factors identified. Such experiments should help elucidate critical factors of Acanthamoeba's biology that could help treat several infections.

Conversion of <i>Campylobacter upsaliensis</i> to the nonculturable but viable coccoid form was characterized. Chloramphenicol did not prevent the conversion. Severe decreases in isocitrate dehydrogenase activity and oxygen uptake and extensive degradation of ribosomal RNA suggest that the coccoid form is a degenerative form rather than part of a life cycle. The autolysins of spiral and coccoid forms of <i>C. upsaliensis</i> were also studied. Autolytic activity in the soluble and sediment fractions of sonicates of the spiral and the coccoid form of <i>C. upsaliensis</i> could not be demonstrated by native (nondenaturing) PAGE. Autolysins were detected, however, by using denaturing SDS-PAGE gels containing either purified <i>E. coli </i> peptidoglycan or whole cells of <i>Micrococcus luteus</i> as the turbid substrate, with subsequent renaturation by treatment with Triton X-100 buffer. In renaturing gels that contained <i>E. coli</i> peptidoglycan, 14 autolytic bands were detected ranging from 200 kDa to 12 kDa. In similar gels containing whole cells of <i>M. luteus</i> , only a single band appeared having a molecular weight of 34 kDa. This band corresponded to one of the bands present in the gels containing <i>E. coli </i> peptidoglycan. This common autolysin was isolated by adsorbing it from <i>C. upsaliensis</i> lysates onto <i>M. luteus</i> cells and then subjecting these cells to renaturing SDS-PAGE in gels containing <i>E. coli</i> peptidoglycan. The 34 kDa autolysin differed from a single 51 kDa autolysin unique to the <i>M. luteus cells</i>. The 34 kDa autolysin was isolated from an SDS-PAGE gel and was pure when tested by isoelectric focusing. The N-terminal amino acid sequence analysis showed the first 15 amino acids of the 34 kDa autolysin to have 67% identity with a part of antigenic protein PEB4 of <i>Campylobacter jejuni</i>. The purified autolysin was used to immunize rabbits and the antibodies produced precipitated autolytic activity from cell lysates. The specificity of the antibodies was shown by Western blotting: only a single specific band occurred, with a molecular weight of 34 kDa, and thus it seems unlikely that the 34 kDa autolysin was derived from any of the other autolysins that were detected. / Ph. D.

Submitted by (edna.saturno@ufrpe.br) on 2017-02-15T12:55:08Z No. of bitstreams: 1 Juliana Ferreira dos Santos.pdf: 1085722 bytes, checksum: bc27ca78be261c584393597a02c7998d (MD5) / Made available in DSpace on 2017-02-15T12:55:08Z (GMT). No. of bitstreams: 1 Juliana Ferreira dos Santos.pdf: 1085722 bytes, checksum: bc27ca78be261c584393597a02c7998d (MD5) Previous issue date: 2008-02-29 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The influence of different dietary concentrations of shrimp protein hydrolysate on the enzymatic activity of intestine of Nile tilapia juveniles were evaluated and correlated with growth parameters (final weight, weight gain, average daily gain, specific growth rate, feed conversion ratio and protein efficiency ratio) and body composition (protein and lipid content). Shrimp protein hydrolysate was included in the diets at concentrations of 0 (SPH 0), 1.5 (SPH 1.5), 3 (SPH 3) and 6% (SPH 6) and a commercial diet was used as reference. The enzymatic activity was carried out using azocasein, BApNA, SApNA, AA- naphytilamide and starch as substrate. Despite some statistical differences observed, there was no logical correlation between enzyme activity and different concentrations of shrimp protein hydrolysate in the diets. Zymogram was also performed to analyze the changes caused by the inclusion of protein hydrolysate on profile of Nile tilapia digestive proteases. Zymograms revealed 12 proteolytic bands, of which 7 have responded to incorporation of shrimp protein hydrolysate. Three trypsins decreased their activity and the inverse was observed for one aminopeptidase. Moreover, three non-identified proteases (lower molecular weight) increased their activity. Bestatin inhibited significantly nine enzymes Nile tilapia intestine, while TPCK, PMSF, Benzamidine and TLCK were less effective. There was a correlation between activity of trypsin and aminopeptidase with some growth parameters, protein and lipid content. It was also found a distinct protease profiles foreach treatment, suggesting the known high adaptability of Nile tilapia to the different diets. / Foi avaliada a influência de diferentes concentrações de hidrolisado protéico de camarão nas atividades enzimáticas dos intestinos de juvenis de tilápia do Nilo, e correlacionadas com parâmetros de crescimento (peso final, ganho de peso, ganho de peso diário, fator de crescimento específico, fator de conversão alimentar, fator de eficiência protéica) e composição do corpo (conteúdo de proteína e lipídio). Hidrolisado protéico de camarão foi incluído nas dietas em concentrações de 0 (SPH 0), 1,5 (SPH 1,5), 3 (SPH 3) e 6% (SPH 6), uma dieta comercial foi usada como referência. O ensaio enzimático foi realizado com os substratos azocaseína, BApNA, SApNA, AA- naphytilamide e amido. Apesar de algumas diferenças estatísticas serem observadas, não houve uma correlação lógica entre atividade enzimática e as diferentes concentrações de hidrolisado protéico de camarão nas dietas. Análises de zimogramas também demonstraram as mudanças causadas pela inclusão de proteína hidrolisada no perfil das proteases digestivas da tilápia do Nilo. Zimogramas revelaram doze bandas proteolíticas, sendo que sete delas responderam a inclusão de hidrolisado protéico de camarão. Três tripsinas diminuíram suas atividades, e o inverso foi observado para uma aminopeptidase. Além disso, três proteases não identificadas (baixo peso molecular)aumentaram suas atividades. Bestatina inibiu significativamente nove enzimas do intestino de tilápia do Nilo, sendo que TPCK, PMSF, Benzamidina e TLCKapresentaram menor efeito. Houve uma correlação entre tripsina e aminopeptidase com alguns parâmetros de crescimento, conteúdo de proteína e lipídio. Também foi observado perfis de proteases distintos para cada tratamento, sugerindo a alta adaptabilidade da tilápia do Nilo a diferentes dietas.

Submitted by Marlene Santos (marlene.bc.ufg@gmail.com) on 2014-11-10T18:07:11Z No. of bitstreams: 2 Dissertação - Douglas Endrigo Perez Pereia - 2014.pdf: 1726049 bytes, checksum: 6458dcad45ca242b032db7ff26c4f792 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Jaqueline Silva (jtas29@gmail.com) on 2014-11-10T20:00:00Z (GMT) No. of bitstreams: 2 Dissertação - Douglas Endrigo Perez Pereia - 2014.pdf: 1726049 bytes, checksum: 6458dcad45ca242b032db7ff26c4f792 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2014-11-10T20:00:00Z (GMT). No. of bitstreams: 2 Dissertação - Douglas Endrigo Perez Pereia - 2014.pdf: 1726049 bytes, checksum: 6458dcad45ca242b032db7ff26c4f792 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2013-05-06 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Lignocellulosic biomass is constituted by cellulose, hemicellulose and lignin in the plant cell walls. The conversion of lignocellulose to fermentable sugars mainly depends on the action of a complex of enzymes that hydrolyze cellulose and hemicellulose. This study was to analyze the production of cellulases and xylanases by fungi isolated from soil and decaying material in Cerrado. Initially, the fungi were analyzed for cellulase production capacity among the fungal cellulase-producing fungus capable of producing the highest levels of cellulase was selected for the experiments of xylanase and cellulase production by submerged fermentation and biochemical analysis of the enzyme secreted. Among the isolated fungi, fungus called IFBMD01 was that higher activity of cellulase in the supernatant when cultivated with wheat bran as carbon source. This was identified as Aspergillus cf niger. The enzymes studied with their respective results were: FPase with better production time of 7 days, showing activity of 0.10 U / mL, optimum pH 5.5, optimum temperature of 60 ° C; CMCase with better time production 6 days, showing activity of 8.19 U / mL, pH optimum of 5, optimum temperature of 70 º C; Avicelase with better production time of 9 days, showing activity of 0.01 U / mL, pH optimum of 5.5 and optimum temperature of 60 ° C; xylanase, with better production time 3 days, showing activity of 35.5 U / mL, and the optimum pH of 5 and the optimum temperature of 50 ° C, the β-Glycosidase, with higher production on the sixth day showing activity of 0.98 U / mL, with the optimum pH 5 and optimum temperature of 60 ° C. The activity of β-glucosidase showing in the culture supernatant was influenced by the ions Mn2 +, NH4, K +, Mg2 +, Ca2 +, Ba2 +, Al3 +, Na +, and Co2+, as well as EDTA, glucose, xylose and cellobiose. In the culture supernatant of the fungus A. niger IFBMD01 grown on FT for 3 and 6 days protein bands were visualized with activity against xylan and CMC molecular weight be 30 to be 66 kDa. / A biomassa lignocelulósica é constituída pela celulose, hemicelulose e lignina, presentes na parede das células vegetais. A xilana é o principal componente da fração de hemicelulose da lignocelulose. A conversão da lignocelulose à açúcares fermentáveis é realizada por um complexo de celulases e xilanases: enzimas que hidrolisam as frações de celulose e xilana. O objetivo deste trabalho foi analisar a produção de celulases e xilanases por fungos isolados a partir de solo e material em decomposição do Bioma Cerrado. Inicialmente, os fungos foram analisados quanto à capacidade de produção de celulases por atividade em placa, neste experimento, os fungos produtores de maiores níveis de celulases foram selecionados para os experimentos de produção de celulases e xilanases por fermentação submersa utilizando meio suplementado com resíduos lignocelulósicos como fonte de carbono. Dentre os fungos analisados, o isolado IFBMD01 apresentou maior atividade de celulases e xilanases no sobrenadante de cultura do fungo cultivado em meio com farelo de trigo, sendo que o pico de produção FPAses, CMCases, Avicelases e xilanases foram obtidos após 7, 6, 9 e 3 dias de cultivo respectivamente. A caracterização bioquímica das celulases e xilanases produzidas pelo isolado IFBMD01 demonstrou que: as enzimas com atividade de FPase apresentaram atividade de 0,10 U/mL, pH e temperatura ótimos de 5,5e 60ºC; as CMCases apresentaram atividade de 8,19 U/mL, pH ótimo de 5 e temperatura ótima de 70ºC; as Avicelases apresentaram atividade de 0,01 U/mL, pH ótimo de 5,5 e temperatura ótima de 60ºC; as xilanase apresentaram atividade de 35,5 U/mL, sendo o pH ótimo de 5 e a temperatura ótima de 50ºC e as β-glicosidases apresentaram atividade de 0,98 U/mL, com o pH ótimo de 5 e temperatura ótima de 60ºC. A atividade de β-glicosidase presente no sobrenadante de cultura foi influenciada pelos íons Mn2+, NH4, K+, Mg2+, Ca2+, Ba2+, Al3+, Na+ e Co2+, assim como por EDTA, glicose, xilose e celobiose. No sobrenadante de cultura do isolado IFBMD01 cultivado em FT por 3 e 6 dias foram visualizadas bandas de proteínas com atividade contra xilana e CMC, com massa molecular aproximada de 30 a 66 kDa. A identificação morfológica e molecular do isolado IFBMD01 demonstrou que é um isolado de Aspergillus cf niger.