Cellulolytic enzyme production from agricultural residues for biofuel purpose on circular economy approach.

This study evaluated the production of cellulolytic enzymes from different agricultural residues. The crude enzyme extract produced was characterized and applied for saccharification of some agricultural residues. Maximum cellulolytic activities were obtained using soybean hulls. All enzymatic activities were highly stable at 40 °C at a pH range of 4.5-5.5. For stability at low temperatures, the enzyme extract was stored at freezing temperature and cooling for about 290 days without major loss of activity. The Km values found for total cellulase (FPase), endoglucanase (CMCase), and xylanase were 19.73 mg ml-1, 0.65 mg ml-1, and 22.64 mg ml-1, respectively, and Vmax values were 0.82 mol min-1 mg-1, 0.62 mol min-1 mg-1, and 104.17 mol min-1 mg-1 to cellulose, carboxymethyl cellulose, and xylan, respectively. In the saccharification tests, the total amount of total reducing sugars (TRS) released from 1 g of soybean hulls catalyzed by the enzymes present in the crude enzyme extract was 0.16 g g-1 dry substrate.

Immobilization of inulinase from Kluyveromyces marxianus NRRL Y-7571 using modified sodium alginate beads.

An experimental design was carried out to evaluate the effect of the concentrations of sodium alginate, glutaraldehyde and activated coal on the immobilization of inulinase from Kluyveromyces marxianus NRRL Y-7571. The experimental condition of 20 g/L of sodium alginate, 50 mL/L of glutaraldehyde and 30 g/L of activated coal led to the highest specific activity (2,063.5 U/mg of protein), corresponding to an enhancement of about 26 times compared to the activity of the free enzyme (79.1 U/mg of protein). The effect of pH and temperature on the immobilized enzyme activity was also evaluated, showing optimal activities at pH of 5.5 and 55 °C. The study of storage of immobilized inulinase in different temperatures showed that the extract kept its initial activity after 43 days of storage at 40 and 50 °C and after 138 days of storage either at 4 or 25 °C.

Characterization of a commercial cellulase for hydrolysis of agroindustrial substrates.

This work is focused on the characterization of a commercial cellulase in terms of optimum pH and temperature, stability to pH and temperature and affinity of this enzyme to several substrates, determining the Michaelis-Menten parameters. Maximum activity of cellulase was obtained for the temperature range from 40 to 50 °C and pH from 5.2 to 5.5. Enzyme activity decreased only 15% after 150 h of reaction at temperatures between 30 and 50 °C. No loss of activity was observed at pH 5.0 and 5.5. The cellulase showed satisfactory results in the hydrolysis of agroindustrial substrates, since similar activity was verified on filter paper and other agroindustrial substrates.

Insecticidal and repellency activity of essential oil of Eucalyptus sp. against Sitophilus zeamais Motschulsky (Coleoptera, Curculionidae).

BACKGROUND: The objective of this work was to evaluate the insecticidal and repellent effect of essential oils of Eucalyptus dunnii, E. saligna, E. benthamii, E. globulus and E. viminalis in the control of Sitophilus zeamais in maize grains. RESULTS: The essential oils chemical composition showed that the E. benthamii presents the cis-ocimene (56.88%) as major compound. Results permitted us to verify that the evaluated species presented different insecticidal action under Sitophilus zeamais. About 100% of mortality was achieved with doses of 65, 100 and 400 microL for E. dunnii, E. saligna and E. benthamii, respectively. After regression analysis the LD(50) values were calculated and E. dunnii was shown to be the most efficient (25.03 microL), followed by E. saligna (37.93 microL) and E. benthamii (121.09 microL). Using the previously calculated LD(50) values, the repellency activity was calculated, allowing us to conclude that all species presented significant values in terms of this important parameter. CONCLUSION: The essential oil of Eucalyptus sp. presented insecticidal and repellency against Sitophilus zeamais Motschulsky (Coleoptera, Curculionidae). Although from an economic point of view synthetic chemicals are still more frequently used as repellents, natural products (essential oils) have the potential to provide efficient and safer repellents for humans and the environment.

Newly Isolated Penicillium sp. for Cellulolytic Enzyme Production in Soybean Hull Residue

Abstract (1) Background: The aim of this study was to evaluate the production and partial characterization of xylanase and avicelase by a newly isolated Penicillium sp. in solid-state fermentation, using soybean hulls as substrate. (2) Methods: Temperature, time, number of spores, and substrate moisture on xylanase and avicelase bioproduction were evaluated, maximizing activity with 30°C, 1x106 spores/g substrate, 14 and 7 days of fermentation with 70 and 76% substrate moisture contents, for xylanase and avicelase, respectively. (3) Results: Different solvents, temperatures, and agitation in the enzymatic extraction were evaluated, obtaining higher activities, 430.77 and 26.77 U/g for xylanase and avicelase using 30 min extraction and 0.05 M citrate buffer solution (pH 4.5 ), respectively at 60°C and 175 rpm and 50°C and 125 rpm. The optimum pH and temperature for enzymatic activity determination were 5.3 and 50°C. Enzyme extract stability was evaluated, obtaining higher stability with pH between 4.5 and 5.5, higher temperature of up to 40°C. The kinetic thermal denaturation (Kd), half-life time, D-value, and Z-value were similar for both enzymes. The xylanase Ed value (89.1 kJ/mol) was slightly lower than the avicelase one (96.7 kJ/mol), indicating higher thermostability for avicelase. (4) Conclusion: In this way, the production of cellulases using alternative substrates is a way to reduce production costs, since they represent about 10% of the world demand of enzymes, with application in animal feed processing, food production and breweries, textile processing, detergent and laundry production, pulp manufacturing and the production of biofuels.

Pretreatment of sugarcane bagasse using supercritical carbon dioxide combined with ultrasound to improve the enzymatic hydrolysis.

This work evaluates the pretreatment of sugarcane bagasse combining supercritical carbon dioxide (SC-CO2) and ultrasound to enhance the enzymatic hydrolysis of pretreated bagasse. In a first step the influence of process variables on the SC-CO2 pretreatment to enhance the enzymatic hydrolysis was evaluated by mean of a Plackett-Burmann design. Then, the sequential treatment combining ultrasound+SC-CO2 was evaluated. Results show that treatment using SC-CO2 increased the amount of fermentable sugar obtained of about 280% compared with the non-treated bagasse, leading to a hydrolysis efficiency (based on the amount of cellulose) as high as 74.2%. Combining ultrasound+SC-CO2 treatment increased about 16% the amount of fermentable sugar obtained by enzymatic hydrolysis in comparison with the treatment using only ultrasound. From the results presented in this work it can be concluded that the combined ultrasound+SC-CO2 treatment is an efficient and promising alternative to carry out the pretreatment of lignocellulosic feedstock at relatively low temperatures without the use of hazardous solvents.