Streptomyces is a genus of Gram-positive bacteria that grows in various environments, and its shape resembles filamentous fungi. The morphological differentiation of Streptomyces involves the formation of a layer of hyphae that can differentiate into a chain of spores. The most interesting property of Streptomyces is the ability to produce bioactive secondary metabolites, such as antifungals, antivirals, antitumorals, anti-hypertensives, immunosuppressants, and especially antibiotics. The production of most antibiotics is species specific, and these secondary metabolites are important for Streptomyces species in order to compete with other microorganisms that come in contact, even within the same genre. Despite the success of the discovery of antibiotics, and advances in the techniques of their production, infectious diseases still remain the second leading cause of death worldwide, and bacterial infections cause approximately 17 million deaths annually, affecting mainly children and the elderly. Self-medication and overuse of antibiotics is another important factor that contributes to resistance, reducing the lifetime of the antibiotic, thus causing the constant need for research and development of new antibiotics.

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Neste trabalho foram avaliados 212 fungos isolados de plantas da Região Amazônica quanto ao potencial de aplicação em biocatálise como fornecedores de lipases ligadas ao micélio. Estes isolados foram submetidos a ensaios de atividade hidrolítica e sintética. Quando submetidos ao ensaio com o substrato tributirina, 87% dos isolados apresentaram atividade hidrolítica. Destes, 30% mostraram bom crescimento em meio líquido indutor de lipase, e foram submetidos à avaliação sintética em reações de esterificação e transesterificação em solvente orgânico. Os nove fungos que apresentaram os melhores desempenhos sintéticos foram avaliados quanto a sua enantiosseletividade na reação de resolução do (R,S)-2-octanol. O isolado UEA_115 foi o biocatalisador mais versátil, apresentando bom desempenho nas reações de esterificação (conversão > 90%) e boa capacidade para a resolução do (R,S)-2-octanol (ee s 29%; ee p 99%; c 22%; E > 200). Com este estudo foi possível demonstrar o grande potencial dos fungos amazônicos como fornecedores de lipases para biocatálise.In this study, 212 fungi were isolated from Amazon region plants, aiming to obtain mycelium bound-lipase-producing biocatalysts. These isolates were submitted to hydrolytic and synthetic activity assays. When submitted to the tributyrine substrate test, 87% of the isolates showed hydrolytic activity. Of these, 30% showed good growth in lipase inducing liquid media and were submitted to evaluation of synthetic activity in esterification and transesterification reactions in organic solvents. The nine fungi which had the best synthetic activity were evaluated in the (R,S)-2-octanol resolution reaction, in order to verify the enantioselectivity of mycelium-bound lipases. The isolate UEA_115 was the most versatile biocatalyst, showing good performance in esterification reactions (conversion > 90%) and good ability for the resolution of (R,S)-2-octanol (ee s 29%; ee p 99%; c 22%; E > 200). Thus, this study has demonstrated the great potential of the Amazonian fungi as lipase suppliers for biocatalysts. Keywords: fungi, Amazon region, mycelium-bound lipase, biocatalyst screening, biocatalysis IntroductionIn recent years, global concern regarding the impact of human actions on the environment has been growing. The implementation of the concept of sustainable development in several productive activities has become an urgent issue. Fortunately, biotechnology also offers an increasing potential to meet the global demands for processes and products in greater harmony with the sustainability concept. 1,2 In this regard, one of the most promising tools in biotechnology is the field of applied biocatalysis, also referred to by some authors as biotransformation or enzymatic technology. 2,3 The advantages of using enzymes as biocatalysts in industrial processes have been shown to be ever more evident. Great versatility of catalyzed reactions, mild reaction conditions, and regio, chemo and enantioselective natures are those most frequently mentioned in the literature. 4 Such characteristic...

Aos meus pais Arlindo e Shigue, os grandes responsáveis pela minha formação, pelo amor e carinho constantes, pela alegria, compreensão e incentivo durante toda a minha vida. Dedico As minhas irmãs que amo tanto Mayrise e Maylena, aos meus cunhados Vlademir e Vítor Fabiano e aos meus queridos sobrinhos, Danilo e Débora, pelo apoio, carinho, amor e torcida para o meu sucesso. Ofereço AGRADECIMENTOS Agradeço a todos aqueles que tornaram possível a realização deste trabalho e de forma especial: À Profa. Dra. Aline A. Pizzirani-Kleiner pela orientação, por ter me apoiado nos momentos mais difíceis, pela confiança e pela valiosa amizade. Ao Dr. Welington Luiz de Araújo pelo apoio indispensável no desenvolvimento desta tese, pela atenção e paciência constantes e a quem tenho profundo agradecimento. Ao Prof. Dr. João Lúcio de Azevedo pelas sugestões, pelo seu exemplo profissional e a quem admiro muito.

Bands of dsRNA were detected in five out of seven isolates of the entomopathogenic fungus Metarhizium flavoviride. The identity of these bands was proven by RNase and S1-nuclease treatments. The transference of dsRNA between isolates (from CG291 to CG442) was successfully carried out through forced heterokaryons. Isogenic strains, with or without dsRNA, were submitted to virulence tests against the grasshopper Rhammatocerus schistocercoides. In contrast to what has been found in some phytopathogenic fungi, these dsRNA fragments did not cause hypovirulence to M. flavoviride.