Volume 8 Issue 4

Sporisorium reilianum is a phytopathogenic fungus that produces the maize head smut. Hydrolytic enzymes such as xylanases have not been studied in this basidiomycete, although these enzymes are widely used within the industry. In this study, the characterization of a xylanase produced by S. reilianum grown in submerged and solid-state fermentation using different culture media was performed. Submerged fermentation with a medium containing birch xylan and yeast extract showed the highest xylanase activity (12.6 U/mL). The enzyme, purified through ion exchange chromatography, had a molecular weight of 42 kDa, as determined by SDS-PAGE, and a Km and Vmax of 1.72 mg/mL and 2.48 μmol/mL/min, respectively. The optimal values of pH and temperature were 5.0 and 70 °C, respectively. The enzyme showed activity over a broad range of temperatures and pHs. Zn2+, Fe3+, and Mn2+ ions increased xylanase activity. Sequence protein analysis showed 100% similarity with the theoretical protein encoded by the sr14403 gene of S. reilianum, encoding a putative endo-b-1,4-xylanase. This is the first report on the production and purification of a xylanase from this fungus, which has interesting biochemical characteristics for application in biotechnological processes.

Hemicellulose material is an abundant and relatively under-utilized hetero-polysaccharide material present in lignocellulosic materials. In this study, an alkaline treatment was applied to sweetgum and Eucalyptus globulus chips to extract hemicelluloses prior to kraft pulping to subsequently evaluate the final product and process. An alkaline extraction (10 and 50% NaOH by weight on wood) for 60 min at 100 °C followed by precipitation in ethanol recovered 4.3% of the biomass as a predominantly xylan material (sweetgum 50% NaOH) with an average degree of polymerization around 250 and functional groups similar to a commercial xylan (sweetgum 10% NaOH). This process in comparison to autohydrolysis (water extraction at 100 °C) produced a much higher molecular weight and more pure hemicellullose. The results obtained indicate a promising combination between the effective extraction of hemicellulose from wood and a distillation process that recovers the ethanol, which may be an attractive alternative to recover liquor and ethanol after hemicellulose precipitation. Hemicellulose from sweetgum showed more thermal stability with high molecular weight compared to the hemicellulose extracted from Eucalyptus globulus. An attractive alternative looks to be to recover liquor and ethanol after hemicellulose precipitation.

Alkaline precipitate isolated from red liquor of acidic magnesium sulfite pulping exhibited obvious stratification. The properties of the stratified alkaline precipitate were investigated via infrared spectroscopy, ion chromatography, thermogravimetric analysis, and high efficiency liquid chromatography. The sulfonic group of lignosulfonate showed a characteristic absorption peak from 1210 cm^-1 to 1170 cm^-1. There were no significant differences between the structures of the functional groups of the upper and lower layers of the precipitate. The peak time of the sulfonic group was 6.350 min, as measured by ion chromatography. Compared with the upper precipitate, the lower precipitate had more groups with high carbon and low oxygen contents and did not easily decompose. The relative molecular weight of the lower precipitate was greater than that of the upper precipitate. The difference in relative molecular weight of the precipitates gave rise to the observed stratification.

Water hyacinth was analyzed to determine its hemicellulose/lignin content, evaluating the conditions for the saccharification process with commercial microbial enzymes. Plant material, including leaves and stalks, was pretreated at several temperatures (100, 110, and 120 °C) with different sulfuric acid concentrations (0.5, 1.0, 1.5, 2.0, 2.5, and 3%) and residence times (0, 15, 30, 45, 60, 90, and 120 min). Total reducing sugars were measured by the dinitrosalicylic acid method. The optimum conditions that maximized the yield of reducing sugars included a pretreatment with 2% (v/v) sulfuric acid at 110 °C for 90 min. The optimum conditions for enzymatic saccharification used the commercial enzyme Celluclast at 50 °C for 24 h of hydrolysis. The maximum yield was 0.54 g of fermentable sugars per gram of biomass. Data demonstrated that E. crassipes is suitable as a raw material for products such as bioethanol; however, further fermentation studies are required.

The vibrational properties of Japanese cedar wood at high temperature were measured. The specimen, its support system, a magnetic driver, and a deflection sensor were placed in an electric drying oven, where vibration tests were conducted. The heating temperatures ranged from 25 ºC to 200 ºC in 25 ºC increments. The resonance frequency decreased with higher heating temperature and decreased most dramatically in the temperature range of 150 ºC to 200 ºC. The loss tangent had a minimum value at 100 ºC and changed more in the temperature range from 150 ºC to 200 ºC than in the range from 25 ºC to 150 ºC. The changes in the resonance frequency and loss tangent of the specimens with larger distance from the pith (d) were smaller than those around the pith. These tendencies are believed to have occurred because the portion with a larger d had a smaller number of intercellular layers than the portion around the pith.

A biodegradable planting container made with rice straw and starch adhesives modified by polyvinyl alcohol was studied in this paper. The effect of heat treatment and polyamide resin on the properties of planting containers was investigated. The physical property and biodegradibility were characterized by means of hygroscopicity, FTIR, degradability, and the thermogravimetric analysis. The results showed that the dry strength of planting containers increased as a result of both treatments. The wet strength of planting containers increased as a result of heat treatment, while the wet strength of planting containers decreased as a result of polyamide resin. The hygroscopicity of planting containers decreased with heat treatment and polyamide resin. The effect of heat treatment was more obvious than the effect of polyamide resin. It was observed that the peak intensity and position were changed for the 3400 cm^-1, 2900 cm^-1, 1640 cm^-1, 1500 cm^-1, 1400 cm^-1, and 1050 cm^-1 under the treatment of polyamide resin. The weight loss of specimens treated with polyamide resin was larger because of the presence of nitrogen in the resin. The appearance of planting containers showed the heat treatment containers were not easily prone to mildew when used for planting. The thermogravimetric analysis (TGA) showed that heat treatment can improve the thermal stability, while the polyamide resin was shown to promote the degradation of planting containers.

In order to decrease the viscosity and improve the wet shear strength of soybean meal (SM) adhesive, in this study, SM adhesive, enzyme-treated SM adhesive(ESM), and the ESM grafted GMA (ESM-g-GMA) adhesive were prepared . The properties of these adhesives were characterized by rheological measurement, mechanical performance testing, Fourier transform infrared spectroscopy (FTIR), and thermogravistric analysis (TGA ). The results indicated that the apparent viscosity of the adhesives decreased due to the enzymatic treatment and the presence of GMA. The wet shear strength of the plywood panels bonded with ESM-g-GMA adhesive was significantly improved from 0.45 MPa to 1.05 MPa, which met the interior plywood requirement (≥0.7 MPa) of the China National Standard. This study also investigated the pot life of the ESM-g-GMA adhesive and the impact of hot pressing. The change in wet shear strength was not obvious within 24 h. The optimum hot press temperature and time were 150 oC and 6 min, respectively. FTIR showed that GMA was successfully grafted onto the ESM adhesive. TGA indicated that the peak degradation temperature of the ESM-g-GMA adhesive was higher than that of the SM adhesive due to the cross-linking reaction that created the macromolecular dense structure between the ESM adhesive and the GMA monomer.

To increase the water resistance and reduce the viscosity of soybean meal (SM)-based non-formaldehyde wood adhesives, polyethyleneglycol diacrylate (PEGDA) used as crosslinker and viscosity reducer was introduced into the SM adhesive system. The apparent viscosity was evaluated by rheological measurements; gel content and water absorption of adhesives, the wet shear strength of plywood bonded with these modified adhesives were tested to evaluate their water resistance. In addition, the crosslink structures of modified adhesives were characterized by Fourier transform infrared (FTIR) spectroscopy and solid-state 13C NMR analysis. The results indicated that all of the SM adhesives were pseudoplastic fluids with the property of shear-thinning. The viscosity of modified SM adhesives effectively decreased by 35% compared with the addition of PEGDA, and the wet shear strength of their bonded plywood increased; the wet shear strength of plywood bonded with 4% PEGDA-modified SM adhesive increased 114.2% compared to SM adhesive. FTIR spectroscopy and solid-state 13C NMR analysis demonstrated that the crosslinking reaction of the PEGDA occurred successfully during the curing process of PEGDA modified SM adhesive, and no crosslinking reaction between the PEGDA and soy meal adhesive appeared to have occurred. Interpenetrating networks (IPNs) might be formed between the cured PEGDA and SM adhesive system.

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.

Pretreatment of forest residues using N-methylmorpholine-N-oxide(NMMO or NMO) prior to anaerobic digestion was investigated, where the effects of particle size, NMMO concentration, and pretreatment time were the primary focus. The pretreatments were carried out on forest residues; with different particle sizes of 2, 4 and 8 mm, at 120 °C for 3, 7, and 15 h in two different modes of NMMO-treatment: dissolution by 85% NMMO and swelling without dissolution using 75% NMMO solution in water. The pretreatment process led to minor changes in the composition of the forest residues. The best improvement in methane yield of the forest residues was achieved by pretreatment using 85% NMMO for 15 h at 120 °C. This treatment resulted in 0.17 Nm3/kg VS methane yield, which corresponds to 83% of the expected theoretical yield of carbohydrates present in the material. Additionally, the accumulated methane yield and the rate of the methane production were highly affected by the amounts of remaining NMMO when it was not well separated during the washing and filtration steps after the treatment. The presence of concentrations even as low as 0.008% NMMO resulted in a decrease in the final methane yield by 45%, while the presence of 1% of this solvent in the digester completely terminated the anaerobic digestion process.