Growth of Chaetomium cellulolyticum on Alkali-Pretreated Hardwood Sawdust Solids and Pretreatment Liquor

The treatment of a hardwood sawdust with 1% NaOH solution at 121°C dissolved 19.7% of the dry matter, mainly hemicellulose and lignin. Fermentation of the treated solids by Chaetomium cellulolyticum for 48 h gave a product containing 12.5% crude protein (total N × 6.25) on a dry weight basis. The in vitro rumen digestibility of the 48-h fermentation product was 30%, compared to 24% for the alkali-treated but unfermented sawdust. Growth was independent of sawdust particle size in the range 40 to 100 mesh. Fermentation of the pretreatment liquor gave a product containing up to 50% crude protein (dry weight basis) with an in vitro rumen digestibility of 65 to 76%. Approximately 6.7 g of crude protein was obtained from the treated solids and 2.2 g from the pretreatment liquor per 100 g of sawdust treated. The product from the pretreatment liquor fermentation has potential as a high-protein animal feed supplement but could not be produced economically without an outlet for the relatively indigestible product from the solids fermentation. Growth on the pretreatment liquor was strongly pH dependent; there was a considerable increase in the lag phase when the pH was lowered from 7.5 to 5.2. This effect appears to be due to an inhibitor whose toxicity is reduced at high pH.     

Biodegradation of tannins in oak (Quercus incana) leaves by Sporotrichum pulverulentum

Fermentation of oak leaves with Sporotrichum pulverulentum decreased the contents of total phenols and condensed tannins by 58 and 66% respectively in 10 d. The protein precipitation capacity decreased by 65%. Further increase of fermentation time up to 40 d did not increase substantially, the tannin degradation. Following fermentation, neutral detergent fibre, acid detergent fibre, hemicellulose, cellulose and lignin decreased by 12–16%, 8–10%, 31–51%, 0.3-3% and 14–15% respectively. The loss in dry matter was from 17–21%. The in sacco dry matter digestibility of the fermented leaves was 17% compared to 27% for the unfermented leaves.     

In vitro studies and short-term feeding trial in lambs to evaluate plantain sheath (Musa sapientum) as a feed for ruminants

Plantain sheath (Musa sapientum) contained 6.4% dry matter and 3.4% crude protein, 31.4% crude fibre, 34.6% cellulose, 15.5% hemicellulose and 6% lignin in dry matter.

Digestibility in vitro studies with fistulated bucks revealed a dry matter disappearance of 53.3% after 24 h incubation. The digestibility of neutral detergent fibre (NDF), acid detergent fibre (ADF) and cellulose after 24 h fermentation was 32.2, 21.5 and 30.3%, respectively. After 48 h fermentation, the dry matter digestibility increased to 63.4%, NDF to 47.0%, ADF to 32.2% and cellulose to 42.3%.

A 45-day feeding trial was conducted with 16 crossbred lambs. Plantain sheath replaced paragrass hay dry matter at 32.6, 54.7 and 76.6% levels. Dried plantain sheath, which contributed 14.1, 25 and 34.5% of total dry matter intake, helped a daily gain of 31.1, 28.9 and 37.8 g when fed mixed with concentrate feed.     

Investigation of the spinnability of cellulose/alkaline ferric tartrate solutions

Dynamic rheology, UV/VIS spectrometry with temperature programming cuvette and reaction calorimetry were conducted on cellulose pulp/FeTNa (NaOH solution containing ferric tartaric acid complex) solutions to investigate their thermostability and spinnability. Color of cellulose/FeTNa solutions changed above 90 °C due to the decomposition of the complex. Thermal activity of cellulose/FeTNa solution started above 130 °C induced by water vapor evolution and complex decomposition. Regeneration of cellulose/FeTNa solutions in a non-solvent (acetic acid and Na-gluconate mixture) resulted in transition from cellulose I into cellulose II structure as revealed by WAXS measurements. Wet-spinning attempts of cellulose/FeTNa solutions yielded fiber-like shaped bodies with a brittle structure.     

Pretreatments to enhance the digestibility of lignocellulosic biomass

Lignocellulosic biomass represents a rather unused source for biogas and ethanol production. Many factors, like lignin content, crystallinity of cellulose, and particle size, limit the digestibility of the hemicellulose and cellulose present in the lignocellulosic biomass. Pretreatments have as a goal to improve the digestibility of the lignocellulosic biomass. Each pretreatment has its own effect(s) on the cellulose, hemicellulose and lignin; the three main components of lignocellulosic biomass. This paper reviews the different effect(s) of several pretreatments on the three main parts of the lignocellulosic biomass to improve its digestibility. Steam pretreatment, lime pretreatment, liquid hot water pretreatments and ammonia based pretreatments are concluded to be pretreatments with high potentials. The main effects are dissolving hemicellulose and alteration of lignin structure, providing an improved accessibility of the cellulose for hydrolytic enzymes.     

枯草芽胞杆菌发酵玉米秸秆后对家蝇的饲养效果

作物秸秆是重要的农业资源,为有效利用作物秸秆,本文利用枯草芽胞杆菌发酵玉米秸秆,配制成人工饲料来饲养家蝇。从菌液加入量和发酵天数来考察对家蝇饲养效果的影响,结果表明:枯草芽胞杆菌菌液加入量为3 mL(3.2×10~(11)cfu/mL),发酵天数3d时对家蝇饲养效果较好,幼虫质量为16.91g,与不加菌液的对照组(13.30g)相比存在显著性差异(P0.05)。经过枯草芽胞杆菌发酵和家蝇幼虫处理后,玉米秸秆的纤维素、半纤维素、木质素的绝对含量都显著降低(P0.05)。经过家蝇取食后的饲料残渣,经检测,有机质等均达到国家标准。最优家蝇饲料配方为:枯草芽胞杆菌菌液加入量3mL(3.2×10~(11) cfu/mL),发酵天数3d,玉米秸秆和麦麸各125g,每250g饲料添加初孵幼虫200mg。本研究利用枯草芽胞杆菌发酵玉米秸秆,提高其营养价值,并进一步饲养家蝇,为秸秆的资源化利用和家蝇规模化饲养奠定了基础。     

稀酸和稀碱预处理对四种不同生物质资源制备还原糖的影响

本论文探讨了不同浓度的稀H_2SO_4和稀NaOH预处理对大豆秸秆、水稻秸秆、象草和狼尾草四种不同生物质酶解制备还原糖的影响。结果表明,大豆秸秆、水稻秸秆、象草和狼尾草具有较高的纤维素和半纤维素含量,是制备还原糖的理想原料。与稀H_2SO_4预处理相比,经稀NaOH预处理后的样品表现出较好的酶解性能。通过使用4%的NaOH对大豆秸秆和狼尾草进行预处理,还原糖产量分别为145.8 mg/mL和319.2 mg/mL。此外,以1%NaOH预处理后的水稻秸秆和象草为原料,可以分别获得385.2 mg/mL和231.6 mg/mL还原糖产量。     

Optimization of processing conditions for the fractionation of triticale straw using pressurized low polarity water

Pressurized low polarity water (PLPW) fractionation of triticale straw was optimized to maximize hemicellulose and lignin yield, and to produce a cellulose rich fraction for biofuels production. The optimum PLPW conditions for hemicellulose yield was determined to be 165 °C, with a flow rate of 115 mL/min, and a solvent-to-solid ratio of 60 mL/g. Hemicellulose and lignin yield generally increased with increasing temperature and solvent-to-solid ratio. There was a small decrease in hemicellulose yield with an increase in flow rate. Minimum lignin content of the triticale straw residue after extraction was predicted to occur at a processing condition of 206 °C, 160 mL/min, and 67 mL/g. PLPW was successful in removing 73-78% of the hemicellulose, leaving a cellulose rich fraction (65% glucose concentration). Lignin was equally distributed between the solid residues and the extracts and most of the hemicellulose was extracted in oligomer form. Remaining solid residues after fractionation were highly digestible by cellulase enzymes.     

Pretreatment of wheat straw for fermentation to methane

The effects of pretreating wheat straw with gamma-ray irradiation, ammonium hydroxide, and sodium hydroxide on methane yield, fermentation rate constant, and loss of feedstock constituents were evaluated using laboratory-scale batch fermentors. Results showed that methane yield increased as pretreatment alkali concentration increased, with the highest yield being 37% over untreated straw for the pretreatment consisting of sodium hydroxide dosage of 34 g OH(-)/kg volatile solids, at 90 degrees C for 1 h. Gamma-ray irradiation had no significant effect on methane yield. Alkaline pretreatment temperatures above 100 degrees C caused a decrease in methane yield. After more than 100 days of fermentation, all of the hemi-cellulose and more than 80% of the cellulose were degraded. The loss in cellulose and hemicellulose accounted for 100% of the volatile solids lost. No consistent effect of pretreatments on batch fermentation rates was noted. Semicontinuous fermentations of straw-manure mixtures confirmed the relative effectiveness of sodium and ammonium-hydroxide pretreatments.     

Comparative ligninolytic and polysaccharolytic potentials of an alkaliphilic basidiomycete on native ligninocellulose

A comparison of the ligninolytic, cellulolytic and hemicellulolytic abilities of an alkaliphilic white-rot fungus. Coprinus fimetarius, on wheat straw under varying conditions of solid-substrate fermentation is presented. The extent of fractional degradation (percentage of the original dry weight of the fraction) of straw under an optimized set of cultural conditions (pH 9·0, moisture 65%, temperature 37°C, period 21 days) was in the following order: lignin (45%), cellulose (42%), hemicellulose (27%). Urea nitrogen favoured the degradation of lignin as well as cellulose and hemicellulose up to a certain level (1·5% sterile urea or 3% unsterile urea on a dry weight basis) beyond which the degradation of lignin was relatively more adversely affected than cellulose. The addition of phosphorus and sulphur was found essential for selective lignin removal. Increasing the C:N ratio by addition of free carbohydrates resulted in an overall decrease in the degradation wherein cellulose utilization was the most affected event. The pre-treatment (physical or chemical) of the substrate caused a general increase in biodegradation of lignin, cellulose and hemicellulose. The degrading activity of the fungus declined with the scaling-up of the fermentation particularly under non-sterile conditions.     

Effect of chemical treatments on the degradability of cotton straw by rumen microorganisms and by fungal cellulase

Three different chemical treatments—sulfur dioxide, ozone, and sodium hydroxide—were applied on cotton straw, and the effect on cell-wall degradability was assessed by using rumen microorganism and Trichoderma reesei cellulase. Sulfur dioxide (applied at 70°C for 72 h) did not change the lignin content of cotton straw but reduced the concentration of hemicellulose by 48%. Ozone exerted a dual effect, both on lignin (a 40% reduction) and hemicellulose (a 54% decrease). The treatment with NaOH did not solublize cell-wall components. The in vitro organic matter digestibility with rumen fluid of cotton straw was increased significantly by ozone and SO₂ treatments, by 120% and 50%, respectively, but not by NaOH. T. reesei cellulase was applied on the chemically pretreated cotton straw at a low level (6 filter paper U/g straw, organic matter), and the release of reducing sugars was determined. The highest level of reducing sugars (30.6 g/100 g organic matter) was obtained with the O₃-cellulase combination, which solubilized 64% of the cellulose and 88% of the hemicellulose. the SO₂- and the NaOH-pretreated cotton straw were hydrolyzed by T. reesei cellulase to the same extent (21 g reducing sugars/100 g organic matter). The rumen fluid digestibility of the enzymatic ally hydrolyzed straw was not increased further over the effect already obtained with the chemical pretreatments. However, the fermentability of the combined treatments was increased markedly. In the O₃-cellulase-treated cotton straw, 83% of the rumen fluid digestible material consisted of highly fermentable components. Although ozone proved to be the most potent pretreatment for enzymic saccharification in this study, the absolute result was modest. The limited effect of the combined O₃-cellulase treatment was probably associated with the pretreatment limitations, but not with the enzyme level. Based on the differential response of the chemically treated cotton straw to attack by rumen microorganisms on the one hand, and by T. reesei cellulase on the other hand, a hypothesis has been suggested as to the location of lignin and hemicellulose in the cellwall unit of cotton straw.     

Alkaline peroxide assisted wet air oxidation pretreatment approach to enhance enzymatic convertibility of rice husk

Pretreatment of rice husk by alkaline peroxide assisted wet air oxidation (APAWAO) approach was investigated with the aim to enhance the enzymatic convertibility of cellulose in pretreated rice husk. Rice husk was presoaked overnight in 1% (w/v) H₂O₂ solution (pH adjusted to 11.5 using NaOH) (equivalent to 16.67 g H₂O₂ and 3.63 g NaOH per 100 g dry, untreated rice husk) at room temperature, followed by wet air oxidation (WAO). APAWAO pretreatment resulted in solubilization of 67 wt % of hemicellulose and 88 wt % of lignin initially present in raw rice husk. Some amount of oligomeric glucose (?8.3 g/L) was also observed in the APAWAO liquid fraction. APAWAO pretreatment resulted in 13‐fold increase in the amount of glucose that could be obtained from otherwise untreated rice husk. Up to 86 wt % of cellulose in the pretreated rice husk (solid fraction) could be converted into glucose within 24 hours, yielding over 21 g glucose per 100 g original rice husk. Scanning electron microscopy was performed to visualize changes in biomass structure following the APAWAO pretreatment. Enzymatic cellulose convertibility of the pretreated slurry at high dry matter loadings was also investigated. © 2011 American Institute of Chemical Engineers Biotechnol. Prog., 2011     

Production of ethanol from wood and agricultural residues by Neurospora crassa

The feasibility of utilizing the rapidly growing tropical woods for ethanol production by Neurospora crassa has been studied. Hydrolysis of cold alkali pretreated wood gave a saccharification of 68% based on the available carbohydrate. The direct fermentation of pretreated wood (20 g l^?1) by Neurospora crassa gave quantitative conversion of available hemicellulose/cellulose to ethanol in 5 days. Increasing the substrate concentration to 50 g l^?1lowered the conversion to 40–60% yielding 12 g l^?1of ethanol. Fermentation of wood (50 g l^?1) pretreated with hot 1 m NaOH followed by neutralization with HCl gave only 6 g l^?1of ethanol.     

Alkali treatment of corn stover to improve sugar production by enzymatic hydrolysis

Alkali treatment of corn stover improves the avaliability of cellulose and hemicellulose for enzymatic attack. Treatments were carried out for 1 to 60 min at temperatures and NaOH concentrations ranging from 100 to 150 degrees C and 0 to 2%, respectively. Solubilization of the stover and sugar production by enzymatic hydrolysis (Trichoderma viride cellulase) of the solid residue and the dissolved solids were used to measure the effect of caustic treatment. At 150 degrees C and 2% NaOH concentration, 65% of the original stover was dissolved after 5 min and 52% saccharificatin (g sugar/g stover) of the residue and dissolved solids by enzymatic hydrolysis was achieved compared to 20% for untreated corn stover.     

Hydrolysis of wheat straw hemicellulose with trifluoroacetic acid. Fermentation of xylose with Pachysolen tannophilus

Treatment of wheat straw with 1N trifluoroacetic acid (TFA) for 7 h at reflux temperature yielded 23% xylose based upon initial straw weight. This corresponds to about an 80% xylose yield based on the xylan content of the hemicellulose. The cellulose component of wheat straw was largely unaffected, as evidenced by low glucose yields. Decomposition of xylose by prolonged refluxing (23 h) was minimal in 1N TFA compared to 1N HCl. Treatment of wheat straw with refluxing 1N TFA converts about 10% of the lignin initially present in straw into water-soluble lignin fragments. Fermentation of the xylose-rich wheat straw hydrolyzate to ethanol with Pachysolen tannophilus was comparable to the fermentation of reagent grade xylose, indicating that furfural and toxic lignin by-products were not produced by 1N TFA in sufficient amounts to impair cell growth and ethanol production. Cellulase treatment of the wheat straw residue after TFA hydrolysis resulted in a 70-75% conversion of the cellulose into glucose.     

Corn fiber, cobs and stover: enzyme-aided saccharification and co-fermentation after dilute acid pretreatment

Three corn feedstocks (fibers, cobs and stover) available for sustainable second generation bioethanol production were subjected to pretreatments with the aim of preventing formation of yeast-inhibiting sugar-degradation products. After pretreatment, monosaccharides, soluble oligosaccharides and residual sugars were quantified. The size of the soluble xylans was estimated by size exclusion chromatography. The pretreatments resulted in relatively low monosaccharide release, but conditions were reached to obtain most of the xylan-structures in the soluble part. A state of the art commercial enzyme preparation, Cellic CTec2, was tested in hydrolyzing these dilute acid-pretreated feedstocks. The xylose and glucose liberated were fermented by a recombinant Saccharomyces cerevisiae strain. In the simultaneous enzymatic saccharification and fermentation system employed, a concentration of more than 5% (v/v) (0.2 g per g of dry matter) of ethanol was reached.     

Ethanol production from candidate energy crops: water hyacinth (Eichhornia crassipes) and water lettuce (Pistia stratiotes L.)

Fermentation modes and microorganisms related to two typical free-floating aquatic plants, water hyacinth and water lettuce, were investigated for their use in ethanol production. Except for arabinose, sugar contents in water lettuce resembled those in water hyacinth leaves. Water lettuce had slightly higher starch contents and lower contents of cellulose and hemicellulose. A traditional strain, Saccharomyces cerevisiae NBRC 2346, produced 14.4 and 14.9 g l(-1) ethanol, respectively, from water hyacinth and water lettuce. Moreover, a recombinant strain, Escherichia coli KO11, produced 16.9 and 16.2 g l(-1) ethanol in the simultaneous saccharification and fermentation mode (SSF), which was more effective than the separated hydrolysis and fermentation mode (SHF). The ethanol yield per unit biomass was comparable to those reported for other agricultural biomasses: 0.14-0.17 g g-dry(-1) for water hyacinth and 0.15-0.16 g g-dry(-1) for water lettuce.     

Effect of inclusion of tree leaves in feed on nutrient utilization and rumen fermentation in sheep

The effect of inclusion of tree leaves in mustard (Brassica campestris) straw (MS) based complete feed blocks (CFB) on nutrient utilization and rumen fermentation was studied in adult male sheep. Four types of CFB diets (Roughage:Concentrate:Molasses, 70:25:5) were prepared. The compaction process increased bulk density (g/cm(3)) of MSB, MSNL, MSSL and MSAL by 2.9, 1.79, 2.40 and 2.26 times, respectively. The dry matter intake (g/day) was higher (P<0.05) in MSSL and MSAL than in MSB. Digestibility coefficients of crude protein and hemicellulose increased (P<0.05) due to inclusion of tree leaves, while digestibility of dry matter and organic matter showed small improvement. However, inclusion of tree leaves did not affect digestibility of neutral detergent fibre, cellulose and energy. The concentration of total volatile fatty acids in rumen was significantly higher in MSAL than in MSB or MSSL. Blood bio-chemical parameters were within the normal physiological range in all the groups.     

Modification of wheat straw in a high-shear mixer

Wheat straw (Ws)was treated in a pilot-scale continuous mixer to disrupt the lignin-hemicellulose-cellulose (LHC) complex. An efficient and practical method was desired to remove lignin and hemicellulose (pentosans)rapidly and efficiently from the lignocellulose complex and to make the cellulose accessible to enzymatic hydrolysis. Milled WS in the presence of various chemicals in aqueous solutions was extruded from the mixer under several processing conditions. Chemicals used were sodium hydroxide (NaOH) sodium sulfide (Na(2)S), anthraquinone (AQ), anthrahydroquinone (AHQ), hexamethylenediamine (HMDA), hexamethylenetetramine (HMTA) hydrogen peroxide (H(2)O(2)), and ferrous ammonium sulfate (FAS), which were used alone and in selected combinations. Concomitantly, WS was treated in laboratory batches using similar reaction conditions, except for mixing and shearing. In extrusion treatments of WS at 20% concentration at 97 degrees C for 5.5 min with NaOH (15.7%, dry WS basis), NaOH (15.7%) + AHQ (0.3%), and NaOH (12.7%) + Na(2)S (5.0%), 64-72% of the WS lignin and 36-43% of the pentosans were removed from aqueously washed extrudates (residues). This compares with 46-56% and 23-27%, respectively, for batch treatments. AHQ and Na(2)S enhanced delignification. Cellulase treatment of the residues, which contained about 99%of the WS cellulose, converted 90-92%of the cellulose to glucose compared with 61-69%for the batch pretreatments. Treatments of WS with amines and H(2)O(2) (alone or combined with NaOH)were less effective for LHC disruption. In all instances the relatively high-shear extrusion treatments were superior to the laboratory-batch treatments.     

Unique purified hydrated-gelatin diet for feeding dietary fiber to Wistar rats

A purified hydrated gelatin diet was developed for feeding dietary fibers to Wistar rats. A dry fiber mix was prepared that consisted of 54.91 dextrose, 13.80 casein, 2.97 AIN mineral mix, 1.28 AIN vitamin mix, 0.17 dl-methionine, 6.80 lard and 5.10 gelatin (g/100g total dry feed). Either cellulose, hemicellulose, lignin, or pectin (15 g/100 g total dry feed) was added to the hydrated dry fiber mix and blended until complete distribution and hydration of the fiber was achieved. After gelling, these hydrated diets were stable for up to 24 hours in environmental conditions commonly encountered in animal facilities. Gel weep was minimal thus permitting feed consumption to be monitored conveniently by weighing the residue in the feeders. In situ examination of stomach contents after feeding such hydrated diets to rats indicated that the gelatin gel was readily degraded and did not confound gel formation by fiber itself. Feed efficiency values (g gain/100 kcal digestible energy) for these diets following a 26-day feeding trial were as follows: no fiber, 6.21; cellulose, 6.38; hemicellulose, 6.23; lignin, 6.52; and pectin, 5.53.