Browsing by Author "Gomes, Eleni"
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Item Enhancing the production of the fermentable sugars from sugarcane straw: A new approach to applying alkaline and ozonolysis pretreatments(2021) Ortega, Julieth Orduña; Mora Vargas, Jorge Andrés; Metzker, Gustavo; Gomes, Eleni; da Silva, Roberto; Boscolo, MauricioThe present study, sugarcane straw residue (SCS) was submitted to a combination of mild alkaline pretreatment and ozone cycles in a rotary reactor aiming to obtain fermentable sugars. The SCS exposed to short ozone cycles and short reaction times proved to be as efficient as long ozone exposure times usually employed, with no significant variation on the concentration of the fermentable sugars. Also, studies carried out on the ozone concentration, ozone exposure time, reaction time and biomass amount on the ozonolysis process were conducted. The washing processes after alkaline pretreatment and ozonolysis were also studied. During the alkaline pretreatment, approximately 73% of total phenolic compounds (TPC) was generated. After the first wash 79% of the TPC was washed away and 95% was removed after the second wash. The TPC content in wash solution obtained after ozonolysis is about 2.3% of the TPC generated with the alkaline pretreatment. For the enzymatic hydrolysate 0.20 g L−1 of TPC was obtained, a low value compared to similar studies. The inhibitor detected in the highest concentration was acetic acid for all solutions, except for ozonolysis where fumaric acid predominated. Hydroxymethylfurfural (HMF) and furfural were detected in amounts of less than 10 mg L−1.Item Production and biochemical characterization of xylanases synthesized by the thermophilic fungus Rasamsonia emersonii S10 by solid-state cultivation(2021) Zanoni, Jéssica De Araujo; Oliveira, Isabela Brunozi De; Perrone, Olavo Micali; Ortega, Julieth Ordunã; Boscolo, Maurício; Gomes, Eleni; Bonilla Rodriguez, Gustavo OrlandoThe xylanolytic enzyme complex hydrolyzes xylan, and these enzymes have various industrial applications. The goal of this work was to characterize the endoxylanases produced by the thermophilic fungus Rasamsonia emersonii in solid-state cultivation. Tests were carried out to evaluate the effects of pH, temperature, glycerol and phenolic compounds on enzyme activity. Thermal denaturation of one isolated enzyme was evaluated. The crude extract from R. emersonii was applied to breakdown pretreated sugarcane bagasse, by quantifying the release of xylose and glucose. The optimum pH value for the crude enzymatic extract was 5.5, and 80 °C was the optimum temperature. Regarding the stability of the crude extract, the highest values occurred between the pH ranges from 4 to 5.5. Several phenolic compounds were tested, showing an increase in enzymatic activity on the crude extract, except for tannic acid. Zymography displayed four corresponding endoxylanase bands, which were isolated by extraction from a polyacrylamide gel. The thermodynamic parameters of isolated Xylanase C were evaluated, showing a half-life greater than 6 h at 80 °C (optimum temperature), in addition to high melting temperature (93.3 °C) and structural resistance to thermal denaturation. Pretreated sugarcane bagasse breakdown by the crude enzymatic extract from R. emersonii has good hemicellulose conversion to xylose.