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A combination of steam explosion (SE) and alkaline peroxide (AP) used to pretreat bamboo was investigated. Steam explosion at 224 °C for 4 min was applied to bamboo, and the pretreated bamboo was delignified by alkaline peroxide. Enzymatic hydrolysis was compared in the pretreated samples. Steam pretreatment led to remarkable hemicellulose solubilization (63.2%). Lignin solubilization (93.1%) was achieved by alkaline peroxide treatment of steam-pretreated bamboo at 80 °C for 1 h in 0.88% (v/v) H2O2, whereas only 33.4% of lignin was solubilized when using raw bamboo. Pretreatment methods resulted in a low degree of polymerization and increased hydrolysis of cellulose. A maximum glucose yield of 90.5% was achieved with a combined steam explosion and alkaline peroxide pretreatment. The surface structure of treated bamboo and the adsorption of enzyme on the substrate were characterized by X-ray photoelectron spectroscopy. Delignification decreased enzyme adsorption and increased enzymatic conversion. SEM analyses indicated that SE-AP pretreatment disrupted lignin networks and exposed crystalline cellulose in bamboo more effectively than SE or AP pretreatment alone. [ABSTRACT FROM AUTHOR]

Abstract: The enzymatic hydrolysis of sugarcane bagasse was investigated by treating a peroxide–alkaline bagasse with a pineapple stem juice, xylanase and cellulase. Pre-treatment procedures of sugarcane bagasse with alkaline hydrogen peroxide were evaluated and compared. Analyses were performed using 24 factorial designs, with pre-treatment time, temperature, magnesium sulfate and hydrogen peroxide concentration as factors. The responses evaluated were the yield of cellobiose and glucose released from pretreated bagasse after enzymatic hydrolysis. The results show that the highest enzymatic conversion was obtained for bagasse using 2% hydrogen peroxide at 60°C for 16h in the presence of 0.5% magnesium sulfate. Bagasse (5%) was treated with pineapple stem extract, which contains mixtures of protease and esterase, in combination with xylanase and cellulase. It was observed that the amount of glucose and cellobiose released from bagasse increased with the mixture of enzymes. It is believed that the enzymes present in pineapple extracts are capable of hydrolyze specific linkages that would facilitate the action of digesting plant cell walls enzymes. This increases the amount of glucose and other hexoses that are released during the enzymatic treatment and also reduces the amount of cellulase necessary in a typical hydrolysis. [ABSTRACT FROM AUTHOR]

Background Efficient conversion of lignocellulosic biomass to fermentable sugars requires the synergistic action of multiple enzymes; consequently enzyme mixtures must be properly formulated for effective hydrolysis. The nature of an optimal enzyme blends depends on the type of pretreatment employed as well the characteristics of the substrate. In this study, statistical experimental design was used to develop mixtures of recombinant glycosyl hydrolases from thermophilic and anaerobic fungi that enhanced the digestion of alkaline peroxide treated alfalfa hay and barley straw by mixed rumen enzymes as well as commercial cellulases (Accelerase 1500, A1500; Accelerase XC, AXC). Results Combinations of feruloyl and acetyl xylan esterases (FAE1a; AXE16A_ASPNG), endoglucanase GH7 (EGL7A_THITE) and polygalacturonase (PGA28A_ASPNG) with rumen enzymes improved straw digestion. Inclusion of pectinase (PGA28A_ASPNG), endoxylanase (XYN11A_THITE), feruloyl esterase (FAE1a) and β-glucosidase (E-BGLUC) with A1500 or endoglucanase GH7 (EGL7A_THITE) and β-xylosidase (E-BXSRB) with AXC increased glucose release from alfalfa hay. Glucose yield from straw was improved when FAE1a and endoglucanase GH7 (EGL7A_THITE) were added to A1500, while FAE1a and AXE16A_ASPNG enhanced the activity of AXC on straw. Xylose release from alfalfa hay was augmented by supplementing A1500 with E-BGLUC, or AXC with EGL7A_THITE and XYN11A_THITE. Adding arabinofuranosidase (ABF54B_ASPNG) and esterases (AXE16A_ASPNG; AXE16B_ASPNG) to A1500, or FAE1a and AXE16A_ASPNG to AXC enhanced xylose release from barley straw, a response confirmed in a scaled up assay. Conclusion The efficacy of commercial enzyme mixtures as well as mixed enzymes from the rumen was improved through formulation with synergetic recombinant enzymes. This approach reliably identified supplemental enzymes that enhanced sugar release from alkaline pretreated alfalfa hay and barley straw. [ABSTRACT FROM AUTHOR]

This study focuses on the extraction of nanocrystalline cellulose (NCC) from the dried stalk of Corchorus olitorius, commonly known as jute, using a combination of a microwave-assisted alkaline peroxide pulping process (AHP) and ultrasonication. Dried jute stalk powder was pretreated using sodium hydroxide under microwave irradiation for the removal of lignin. The partially delignified sample was bleached using 30% hydrogen peroxide solution. The resulting crude cellulose was hydrolyzed using ultrasonication in the presence of ionic liquid and sulfuric acid. The effect of hydrolyzing medium on the physicochemical characteristics of the extracted nanocellulose was investigated. The nanocrystalline cellulose (NCC) obtained after combined treatments was rod-like, with diameters of 10 to 15 nm and lengths of 92 to 105 nm. Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction analysis (XRD) showed that some breakages of intramolecular hydrogen bonds and glycosidic bonds occurred during the hydrolysis reaction of pretreated biomass. Ultrasonication in the presence of an acid hydrolyzing medium most effectively accelerated these breakages in the long chain cellulose biopolymer, leading to the formation of nanocrystalline cellulose (NCC) with higher crystallinity. [ABSTRACT FROM AUTHOR]

The viability of most fermentation processes is very much dependent on the cheap fermentation medium used. Palm kernel cake (PKC) is an abundant biomass generated from the palm oil processing industry that can be used as the carbon source for the growth and production of acetone-butanolethanol fermentation (ABE) by Clostridia. In this study, ABE production from the fermentation of PKC using Clostridium acetobutylicum YM1 in a batch culture was conducted. The PKC was subjected to treatment with acids (sulphuric and hydrochloric acids), alkali (sodium hydroxide and alkaline peroxide), enzymatic hydrolysis, and hydrothermal treatment (in autoclave). The sulphuric acid-treated PKC (2% SAPKC) method produced the highest concentration of reducing sugars (30 g/L) compared with the other methods applied. The results showed that increasing the concentration of H2SO4 up to 3% decreased the amounts of generated reducing sugars to 20.4 g/L, which is about 32% less. The fermentation of 1%, 2%, and 3% SAPKC resulted in the production of ABE of 1.07, 5.72, and 3.48 g/L, respectively. This study showed that the pretreatment of PKC improved the content of fermentable sugars and subsequently enhanced the production of ABE by C. acetobutylicum YM1. This study also revealed that PKC can be regarded as a potentially low cost substrate for ABE fermentation. [ABSTRACT FROM AUTHOR]

King Grass is a fast growing, high yield, hybrid grass that grows in a variety of soil conditions and does not compete with food crops. King Grass is perennial and can be harvested several times per year. Therefore it has a high potential for ethanol production in tropical countries. The pretreatments alkaline delignification (66.6–133 °C, 30–180 min, solid to liquid ratio 1:13.3–1:20 wt and NaOH concentration 0.7–2% wt), diluted acid hydrolysis (2% wt sulfuric acid, solid to liquid ratio of 1.0 g biomass/mL solution, stirring at 90 °C for 90 min), steam explosion (at 180 °C for 5 min, i.e., severity 3.05), alkaline peroxide (2% vol. H 2 O 2 , liquid to solid ratio of 20:1 wt, pH 11.5, stirring at 35 °C for 3 h) and aqueous ammonia soaking (15% wt ammonia solution, 8 mL of ammonia solution per gram of material, at 60 °C for 6 h) were studied. The alkaline pretreatment with NaOH led to the highest concentration of reducing sugars, i.e., 58.6 g/L, and to the highest ethanol concentration, i.e., 17.9 g/L. A more detailed study of the effect of the alkaline pretreatment conditions (temperature, solid to liquid ratio, NaOH concentration and residence time) on the production of ethanol from King Grass was carried out. Under pretreatment conditions of 120 °C for 1 h with 2% wt NaOH and a solid to liquid ratio of 1:20 the highest ethanol yield reported so far was obtained, i.e., 27.7 g/L (165.9 mg ethanol/g dry biomass, 92% of theoretical yield). Furthermore, this pretreatment allowed the removal of most of lignin present in King Grass, i.e., 94%, and allowed a high recovery of the cellulosic fraction in the solid (93–99%). Under typical growing conditions of King Grass in Colombia this maximum ethanol yield corresponds to 12,616 L/ha/year which is higher than that obtained from sugar cane bagasse (4602 L/ha/year). [ABSTRACT FROM AUTHOR]