Pretreated Sugarcane Bagasse Result in More Efficient Degradation by Streptomyces sp S2

Streptomyces genera plays important role in lignocellulose degradation. Many research founds Streptomyces has cellulolytic and ligninolytic enzymes that sufficient to degrade lignocellulosic materials. However, minimum lignocellulosic material condition that can efficiently degraded by Streptomyces sp. has not been fully understood. In this research, three pretreament conditions (physical, alkaline-hydrotermal, and hydrogen-peroxide chemical treatments) of sugarcane bagasse used as lignocellulosic material, to further degraded by Streptomyces sp. S2. Lignocellulose component measurement conclude that raw (physical treated only) bagasse wasn’t efficiently degraded by Streptomyces sp S2. Hydrogen-peroxide was effective on reducing both syringil and guaiacyl lignin, meanwhile alkaline-hydrotermal pretreatment was very effective on reducing syringil lignin. This study suggest that hydrogen-peroxide pretreatment can be used in many type of lignocellulosic material, which can be further degraded by Streptomyces sp. S2. Alkaline-hydrotermal preteatment on the other hand is best suited to degrade lignocellulosic material that have high percentage of syringil lignin.

IMMOBILIZATION OF CELLULASES ON CHITOSAN: APPLICATION FOR SUGARCANE BAGASSE HYDROLYSIS

In this work, a commercial cellulolytic cocktail was immobilized on glutaraldehyde activated chitosan gel. The chitosan concentration in the gel preparation, pH, immobilization time and enzymatic loading were evaluated. Immobilized cellulases showed better hydrolysis performance when an enzyme loading of 134 mg protein/g carrier was used for immobilization at pH 9.0 for 30 minutes. Hydrolysates with a glucose content of 13.43 and 10.35 g/L were obtained when Avicel and pretreated sugarcane bagasse were used as substrate, respectively. Immobilized cellulase lost 60% of its hydrolysis performance after 8 cycles using Avicel, and 75% after 6 cycles for sugarcane bagasse. The hydrolysis performance associated with the reuse of the immobilized cellulases indicates that an improvement in the immobilization of cellulases, coupled with an improvement in the pretreatment of lignocellulosic biomass, will allow the development of a continuous hydrolysis system with the enzyme retained in the reactor.

Production and biochemical characterization of xylanases synthesized by the thermophilic fungus Rasamsonia emersonii S10 by solid-state cultivation

The 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.