cellulase and sodium-bisulfite

Topics: Carbohydrates; Cellulase; Ethylenediamines; Glucose; Hydrogen Peroxide; Hydrolysis; Maillard Reaction; Models, Theoretical; Molecular Weight; Sodium Hypochlorite; Spectroscopy, Fourier Transform Infrared; Sulfites; Temperature; Waste Products; Xylose; Zea mays

This study investigates the potential for extracting sugars from the polysaccharides of Eastern redcedar. Pretreatment temperature, time, sulfuric acid loading, sodium bisulfite loading and impregnation time were varied using factorial treatment design experiments for identifying near optimal overall wood glucan-to-glucose yields during acid bisulfite pretreatments. The highest overall wood glucan-to-glucose yield of 87% was achieved when redcedar was impregnated with pretreatment liquor containing 3.75 g of sulfuric acid/100g of dry wood and 20 g of sodium bisulfite/100g of dry wood at 90 °C for 3h followed by increasing the temperature to 200 °C with a hold time of 10 min. Hemicellulose and lignin removal during pretreatments made the substrate amenable to enzymatic hydrolysis using 0.5 ml of Accelerase® 1500/g of glucan at 2% (w/w) solid loading. Preliminary mass balances showed 97% glucan recovery at pretreatment condition with 87% overall wood glucan-to-glucose yield and 59% delignification.

Topics: Biotechnology; Carbohydrate Metabolism; Cellulase; Glucans; Glucose; Hydrolysis; Juniperus; Sulfites; Sulfuric Acids; Surface-Active Agents; Temperature; Time Factors; Wood

Lodgepole wood chips were pretreated by sulfite pretreatment to overcome recalcitrance of lignocelluloses (SPORL) at 25% solids loading and 180 °C for 20 min with sulfuric acid and sodium bisulfite charges of 2.2 and 8 wt/wt% on an oven-dry wood basis, respectively. The pretreated wood chips were disk-milled with pretreatment spent liquor and water, and the solid fraction was separated from the liquor stream. The liquor was neutralized and concentrated through vacuum evaporation. Quasi-simultaneous enzymatic saccharification of the cellulosic solids and combined fermentation with the concentrated liquor was conducted at up to 20% total solids loading. Fed-batching of the solids facilitated liquefaction and saccharification, as well as managing instantaneous inhibitor concentrations. At a commercial cellulase (CTec2) loading of only 9 FPU or 0.06 mL/g untreated wood, a maximum ethanol titer of 47.4 g/L was achieved, resulting in a calculated yield of 285 L/tonne of wood using Saccharomyces cerevisiae YRH400 at 35 °C and pH 5.5.

Topics: Biofuels; Cellulase; Ethanol; Fermentation; Pinus; Saccharomyces cerevisiae; Sulfites; Sulfuric Acids

Native aspen (Populus tremuloides) was pretreated using sulfuric acid and sodium bisulfite (SPORL) and dilute sulfuric acid alone (DA). Simultaneous enzymatic saccharification and fermentation (SSF) was conducted at 18% solids using commercial enzymes with cellulase loadings ranging from 6 to 15 FPU/g glucan and Saccharomyces cerevisiae Y5. Compared with DA pretreatment, the SPORL pretreatment reduced the energy required for wood chip size-reduction, and reduced mixing energy of the resultant substrate for solid liquefaction. Approximately 60% more ethanol was produced from the solid SPORL substrate (211 L/ton wood at 59 g/L with SSF efficiency of 76%) than from the solid DA substrate (133 L/ton wood at 35 g/L with SSF efficiency 47%) at a cellulase loading of 10 FPU/g glucan after 120 h. When the cellulase loading was increased to 15 FPU/g glucan on the DA substrate, the ethanol yield still remained lower than the SPORL substrate at 10 FPU/g glucan.

Topics: Biofuels; Cellulase; Chromatography, Gas; Chromatography, Ion Exchange; Ethanol; Fermentation; Populus; Saccharomyces cerevisiae; Sulfites; Sulfuric Acids

This study investigated the effects of chemical pretreatment and disk-milling conditions on energy consumption for size-reduction and the efficiency of enzymatic cellulose saccharification of a softwood. Lodgepole pine wood chips produced from thinnings of a 100-year-old unmanaged forest were pretreated by hot-water, dilute-acid, and two SPORL processes (Sulfite Pretreatment to Overcome Recalcitrance of Lignocellulose) at acid charge on oven dry (od) wood of 0% and 2.21%. The pretreated wood chips were then milled using a laboratory disk mill under various solids-loadings and disk-plate gaps to produce substrates for enzymatic hydrolysis. We found that post-chemical-pretreatment size-reduction of forest biomass can decrease size-reduction energy consumption by 20-80% depending on the pretreatment applied under 20% solids-loading and a disk-plate gap of 0.76 mm in milling. SPORL with a sodium bisulfite charge of 8% and sulfuric acid charge of 2.21% on wood was the most effective in decreasing size-reduction energy consumption. Solids-loading had the most significant effect on disk-milling energy. When solids-loading was reduced from 30% to 3%, disk-milling energy could be decreased by more than a factor of 10 for wood chips pretreated by both SPORL and dilute-acid at an acid charge of 2.21%. The enzymatic hydrolysis glucose yields (EHGY) from the substrates produced by all pretreatments were independent of the solids-loading in milling, indicating that these energy savings in size-reduction can be realized without affecting EHGY. When wood chips were pretreated by SPORL with 2.21% acid charge, size-reduction energy consumption was decreased to less than 50 Wh/kg od wood at a practical solids-loading of approximately 10-20%, equivalent to that used in size-reduction of agriculture biomass, with excellent EHGY of about 370 g per kg od wood. Similar effects on size-reduction energy savings and excellent EHGY were also achieved when large disk-plate gaps (up to 1.52 mm studied) were applied in disk-milling of wood chips pretreated by SPORL with acid.

Topics: beta-Glucosidase; Biofuels; Biotechnology; Cellulase; Chromatography, Ion Exchange; Conservation of Energy Resources; Hydrolysis; Pinus; Sulfites; Sulfuric Acids; Wood