Dilute acid pretreatment for enhancing the enzymatic saccharification of agroresidues using a Botrytis ricini endoglucanase.

The enormous amount of agroindustrial residues generated in Brazil can be used as biomass to produce fermentable sugars. This study compared the pretreatments with different proportions of dilute acid. The method involved pretreatment with 0.5%, 1%, and 1.5% (v/v) sulfuric acid, followed by hydrolysis using the halotolerant and thermostable endoglucanase from Botrytis ricini URM 5627. The physicochemical characterization of plant biomass was performed using XRD, FTIR, and SEM. The pretreatment significantly increased the production of fermentable sugars following enzymatic saccharification from wheat bran, sugarcane bagasse, and rice husk: 153.67%, 91.98%, and 253.21% increment in sugar production; 36.39 mg⋅g-1 ± 1.23, 39.55 mg⋅g-1 ± 1.70, and 42.53 mg⋅g-1 ± 7.61 mg⋅L-1 of glucose; and 3.26 ± 0.35 mg⋅g-1 , 3.61mg⋅g-1 ± 0.74 and 3.59 mg⋅g-1 ± 0.80 of fructose were produced, respectively. In conclusion, biomass should preferably be pretreated before the enzymatic saccharification using B. ricini URM 5627 endoglucanase.

Thermostable trypsin-like protease by Penicillium roqueforti secreted in cocoa shell fermentation: Production optimization, characterization, and application in milk clotting.

The increased demand for cheese and the limited availability of calf rennet justifies the search for milk-clotting enzymes from alternative sources. Trypsin-like protease by Penicillium roqueforti was produced by solid-state fermentation using cocoa shell waste as substrate. The production of a crude enzyme extract that is rich in this enzyme was optimized using a Doehlert-type multivariate experimental design. The biochemical characterization showed that the enzyme has excellent activity and stability at alkaline pH (10-12) and an optimum temperature of 80°C, being stable at temperatures above 60°C. Enzymatic activity was maximized in the presence of Na+ (192%), Co2+ (187%), methanol (153%), ethanol (141%), and hexane (128%). Considering the biochemical characteristics obtained and the milk coagulation activity, trypsin-like protease can be applied in the food industry, such as in milk clotting and in the fabrication of cheeses.

Comparison between the univariate and multivariate analysis on the partial characterization of the endoglucanase produced in the solid state fermentation by Aspergillus oryzae ATCC 10124.

Endoglucanase production by Aspergillus oryzae ATCC 10124 cultivated in rice husks or peanut shells was optimized by experimental design as a function of humidity, time, and temperature. The optimum temperature for the endoglucanase activity was estimated by a univariate analysis (one factor at the time) as 50°C (rice husks) and 60°C (peanut shells), however, by a multivariate analysis (synergism of factors), it was determined a different temperature (56°C) for endoglucanase from peanut shells. For the optimum pH, values determined by univariate and multivariate analysis were 5 and 5.2 (rice husk) and 5 and 7.6 (peanut shells). In addition, the best half-lives were observed at 50°C as 22.8 hr (rice husks) and 7.3 hr (peanut shells), also, 80% of residual activities was obtained between 30 and 50°C for both substrates, and the pH stability was improved at 5-7 (rice hulls) and 6-9 (peanut shells). Both endoglucanases obtained presented different characteristics as a result of the versatility of fungi in different substrates.

Prickly palm cactus husk as a raw material for production of ligninolytic enzymes by Aspergillus niger.

Prickly palm cactus husk was used as a solid-state fermentation support-substrate for production of the ligninolytic enzymes laccase, peroxide manganese, and lignin peroxidase by Aspergillus niger. Effects of water activity, temperature, and fermentation time on enzymatic production were evaluated using a central composite rotatable design. Response surface methodology revealed that maximum enzyme production was achieved at 73.38 h of fermentation, a water activity of 0.87 Aw, at 28.74°C for laccase, at 65.33 h, 0.89 Aw, and 28.96°C for lignin peroxidase, and at 70.44 h, 0.91 Aw, and 28.84°C for manganese peroxidase. Optimized enzyme production was 9,023.67 UI/L for laccase, 2,234.75 UI/L for lignin peroxidase, and 8,534.81 UI/L for manganese peroxidase. Thermostability and pH stability were observed for all enzymes. Enzymatic deactivation kinetic experiments indicated that enzymes remained active after freezing of crude extracts.