Maria Teresa Borges Pimenta

The Penicillium echinulatum Secretome on Sugar Cane Bagasse

Plant feedstocks are at the leading front of the biofuel industry based on the potential to promote economical, social and environmental development worldwide through sustainable scenarios related to energy production. Penicillium echinulatum is a promising strain for the bioethanol industry based on its capacity to produce large amounts of cellulases at low cost. The secretome profile of P. echinulatum after grown on integral sugarcane bagasse, microcrystalline cellulose and three types of pretreated sugarcane bagasse was evaluated using shotgun proteomics. The comprehensive chemical characterization of the biomass used as the source of fungal nutrition, as well as biochemical activity assays using a collection of natural polysaccharides, were also performed. Our study revealed that the enzymatic repertoire of P. echinulatum is geared mainly toward producing enzymes from the cellulose complex (endogluganases, cellobiohydrolases and β-glucosidases). Glycoside hydrolase (GH) family members, important to biomass-to-biofuels conversion strategies, were identified, including endoglucanases GH5, 7, 6, 12, 17 and 61, β-glycosidase GH3, xylanases GH10 and GH11, as well as debranching hemicellulases from GH43, GH62 and CE2 and pectinanes from GH28. Collectively, the approach conducted in this study gave new insights on the better comprehension of the composition and degradation capability of an industrial cellulolytic strain, from which a number of applied technologies, such as biofuel production, can be generated.

Physical and chemical studies of tungsten carbide catalysts: effects of Ni promotion and sulphonated carbon

Ni promoted tungsten carbides have been shown to be an effective catalyst for cellulose conversion reaction. With the use of both in situ and ex situ techniques an investigation into the physical and chemical aspects of the Ni-promoted tungsten carbide catalyst supported on activated carbon either in pure form or functionalized with sulfuric acid was conducted. In situ XRD analysis performed during the carburization process showed that non-promoted samples formed a mixture of nanosized W2C, WC1−x and WC carbide phases. In the case of Ni promoted catalysts, in situ XRD, XANES, XPS and TEM analysis revealed that Ni aids in lowering the carburization temperature by 50 °C but also assisted in the deposition of polymeric carbon onto the catalyst surface which reduced cellulose conversion. However, the results indicate beneficial effects caused by the high carbon coverage by stopping the W2C to WC carbide phase transition. Thus, carburization of Ni promoted samples produced only W2C phase, which is stable up to 800 °C. The functionalization of activated-carbon with –SO3H not only increases the hydrolysis of cellulose but also lead to a greater dispersion of Ni over the catalyst. The resulting improvement in the interaction between Ni/W/C increases the cellulose transformation in a one-pot synthesis towards the production of ethylene glycol.