Produção de celulases por fungos de ambiente marinho e terrestre para uso na hidrólise do bagaço de cana-de-açúcar e produção de 2,3-butanodiol pela bactéria <i>Serratia marcescens</i> a partir de glicose e glicerol

Abstract

In Chapter 1 it is reported the cellulase production by 4 marine-derived fungi strains (Aspergillus sydowii CBMAI 934, A. sydowii CBMAI 935, Penicillium citrinum CBMAI 1186 and Mucor racemosus CBMAI 847) and 1 terrestrial fungi strain (Aspergillus sp. CBMAI 1198). They were grown in solid state fermentation using wheat straw as substrate (5 g) and with addition of peptone solution (0,75 g.L -1 ) enriched with inorganic salts. It was performed the enhancement of the growth conditions by changing the temperature, initial pH and moisture. The optimum temperature for all strains varied between 25-35 °C but A. sydowii CBMAI 935 with 40 °C. The optimum pH was different for each strain, varying from acidic to alkaline conditions. The optimum moisture content also varied accordingly the studied strain. In order enhance the cellulose hydrolysis performed by the produced cellulases, it was varied the pH, temperature and amount of the crude cellulase extract during the filter paper hydrolysis reaction. The obtained optimum values were different among strains and, in some cases, there were two optimum pH and temperature for the hydrolysis of the filter paper. Then, the obtained cellulases, using the best conditions for hydrolysis, were used in the sugarcane bagasse hydrolysis (10 FPU/g of sugarcane bagasse). The cellulases from the strains Aspergillus sp. CBMAI 1198 and A. sydowii CBMAI 934 were capable of degrading 75% and 78% of the sugarcane bagasse, respectively, generating reducing sugars. In Chapter 2, the capability of 6 strains (Bacillus subtilis LQOB-SE1, B. coagulans LQOB-SE2, B. pumillus LQOB-SE3, Brevibacillus brevis LQOB-SE4, Lysinibacillus sp. LQOB-SE5 and Serratia marcescens LQOB-SE6), isolated from peat soil, of producing 2,3-butanediol from glycerol fermentation. The only strain that produced 2,3-butanediol was S. marcescens LQOB-SE6, which was also applied in 2,3-butanediol production from glucose fermentation. Therefore, wastes from biodiesel and bioethanol production can be reused in industrial scale. The best conditions for glycerol fermentation: initial pH 7, Nutrient Broth (8 g. Tabela 3. Rendimento e produtividade obtidos de 2,3-butanodiol a partir da fermentação do glicerol pela bactéria S. marcescens LQOB-SE6 ao longo do tempo de cultivo. 182Tabela 4. Comparação entre os valores de rendimentos e produtividades obtidos na produção de 2,3-butanodiol a partir da fermentação do glicerol com resultados descritos na literatura para diferentes microrganismos. 183Tabela 5. Rendimentos e produtividades obtidos a partir da fermentação da glicose pela bactéria S. marcescens LQOB-SE6 ao longo do tempo de cultivo. 191Tabela 6. Dados de rendimentos e produtividades obtidos na produção de 2,3-butanodiol a partir da fermentação da glicose com microrganismos relatados na literatura e com a bactéria S. marcescens LQOB-SE6.