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1.
Rice straw was fermented with Cellulomonas sp. and Alcaligenes faecalis. Microbial cells and undigested residue, as well as chemically treated (NaOH or NH4OH) and untreated straws, were analyzed for nutrient composition and in vitro digestibility. In a typical fermentation, 75% of the rice straw substrate was digested, and 18.6% of the total substrate weight that disappeared was recovered as microbial protein. The microbial cell fraction was 37% protein and 5% crude fiber; the residue was 12% protein and 45% crude fiber. The microbial protein amino acid profile was similar to alfalfa, except for less cysteine. The microbial cells had more thiamine and less niacin than Torula yeast. In vitro digestibility of the microbial protein was 41.2 to 55%; that of cellulose was 52%.  相似文献   

2.
Activities of several enzymes associated with cellulolysis were compared using as substrates cell-walls of Lolium multiflorum and cotton cellulose. Purified enzymes C1 (see Ref. 1 for definition), C.x (CM-cellulase) and β-glucosidase were employed as well as culture filtrates containing Cx. Activities were determined by ability to digest the substrates and to release H2O-soluble phenolic compounds from the grass cell-walls. The culture filtrates most active on cotton cellulose were obtained using the fungi Trichoderma viride and Fusarium solani; with grass cell-walls the most active were from T. viride, Gliocladium roseum, a species of Basidiomycetes, and one strain of Myrothecium verrucaria (IMI Strain 25 291). For the crude enzyme preparations tested, there were highly significant correlations between the digestibility of grass cell-walls and the UV-absorption of the filtrate at λmax 290 nm and at λmax 324 nm but there was no significant correlation between the digestibility of grass cell-walls and that of cotton cellulose. Partially purified C1 and Cx from two different fungal sources showed activity on both substrates. Differences in MW of the H2O-soluble phenolic compounds obtained by treatment of grass cell-walls with C1 and Cx components suggest that these enzymes could have different modes of action. Synergism between C1 and Cx from T. koningii occurred with both substrates but with C1 and Cx from F. solani synergism only occurred with cotton cellulose.  相似文献   

3.
《Small Ruminant Research》2003,47(3):203-212
Effects of sodium bicarbonate (NaHCO3) inclusion on rumen fermentation characteristics and ciliate protozoal population in high concentrate-fed lambs were studied. Twenty-four weaner (90 days old) Malpura lambs divided into four equal groups (G1, G2, G3 and G4) were fed basal (25:75 roughage and concentrate) diet (G1) or basal diet supplemented with 0.75% (G2), 1.50% (G3) and 2.25% (G4) sodium bicarbonate for 90 days. Daily dry matter (DM) intake and digestibility of organic matter (OM), crude protein (CP), gross energy and plane of nutrition were similar in all the groups while cellulose digestibility was higher in G4 than in G2 and G1. Ruminal pH increased (P<0.05) with increasing levels of dietary sodium bicarbonate. Concentrations of total volatile fatty acids (TVFA), total nitrogen and trichloroacetic acid-precipitable nitrogen (TCA-ppt.-N) were higher while ammonia nitrogen was lower in the rumen fluid of G4 and G3 than in G2 and G1. The number of total protozoa, Isotricha, Dasytricha, large and small spirotrichs were higher (P<0.01) in the rumen of G4 and G3 than in G2 and G1. Total live weight gain and average daily gain were also higher in lambs supplemented with sodium bicarbonate. It is concluded that sodium bicarbonate inclusion at the rate of 1.50% of total ration increased cellulose digestibility, ciliate protozoal number, ruminal pH and total nitrogen concentration resulting in improved growth of lambs maintained on high concentrate diet.  相似文献   

4.
Wan C  Li Y 《Bioresource technology》2011,102(16):7507-7512
Different types of feedstocks, including corn stover, wheat straw, soybean straw, switchgrass, and hardwood, were tested to evaluate the effectiveness of fungal pretreatment by Ceriporiopsis subvermispora. After 18-d pretreatment, corn stover, switchgrass, and hardwood were effectively delignified by the fungus through manganese peroxidase and laccase. Correspondingly, glucose yields during enzymatic hydrolysis reached 56.50%, 37.15%, and 24.21%, respectively, which were a 2 to 3-fold increase over those of the raw materials. A further 10-30% increase in glucose yields was observed when pretreatment time extended to 35 d. In contrast, cellulose digestibility of wheat straw and soybean straw was not significantly improved by fungal pretreatment. When external carbon sources and enzyme inducers were added during fungal pretreatment of wheat straw and soybean straw, only glucose and malt extract addition improved cellulose digestibility of wheat straw. The cellulose digestibility of soybean straw was not improved.  相似文献   

5.
Corn is a major food crop with enormous biomass residues for biofuel production. Due to cell wall recalcitrance, it becomes essential to identify the key factors of lignocellulose on biomass saccharification. In this study, we examined total 40 corn accessions that displayed a diverse cell wall composition. Correlation analysis showed that cellulose and lignin levels negatively affected biomass digestibility after NaOH pretreatments at p<0.05 & 0.01, but hemicelluloses did not show any significant impact on hexoses yields. Comparative analysis of five standard pairs of corn samples indicated that cellulose and lignin should not be the major factors on biomass saccharification after pretreatments with NaOH and H2SO4 at three concentrations. Notably, despite that the non-KOH-extractable residues covered 12%–23% hemicelluloses and lignin of total biomass, their wall polymer features exhibited the predominant effects on biomass enzymatic hydrolysis including Ara substitution degree of xylan (reverse Xyl/Ara) and S/G ratio of lignin. Furthermore, the non-KOH-extractable polymer features could significantly affect lignocellulose crystallinity at p<0.05, leading to a high biomass digestibility. Hence, this study could suggest an optimal approach for genetic modification of plant cell walls in bioenergy corn.  相似文献   

6.
《Biological Wastes》1987,19(4):275-280
The basidiomycete cultures, Polyporus strains BH1 and BW1, were cultivated on whole bagasse substrate in a solid-state system. The cultures degraded cellulose, hemicellulose and lignin contents of bagasse, increasing the digestibility and protein content of the product, to be utilized as cattle feed. Untreated and unwashed bagasse proved a good substrate.  相似文献   

7.
Semisolid fermentation of ryegrass straw   总被引:4,自引:3,他引:1       下载免费PDF全文
Candida utilis, Aureobasidium pullulans, and Trichoderma viride were grown on pretreated ryegrass straw. The pretreatment consisted of hydrolysis of straw with 0.5 N H2SO4 (water-substrate, 3:1) at 121 C, 100 C, and room temperature and adjustment of the hydrolysate to pH 4.5 to 5.0 with 5 N NH4OH. The 121 C pretreatment yielded a material containing 30% sugar and 2.3% N. The fermentation was carried on semisolid substrate (moisture level, 75%) in rotating jars for 2 to 3 days at room temperature. The organisms grew rapidly during the period from 18 to 42 h of incubation. During this period the number of microbial cells increased by 20- to 200-fold, and the level of NH3-N decreased from 1.3 to 0.9%. The fermentation resulted in a fourfold increase in protein, fivefold increase in crude fat, and 40% increase in the digestibility of straw. The best result in terms of increasing protein and digestibility of straw was obtained when C. utilis was grown on straw preheated at 121 C.  相似文献   

8.
Chopped maize stover, ammoniated at ambient and elevated temperatures or steamed, was evaluated with eight wether lambs in a 4 × 4 double Latin square design. Treatments were: (i) control, 60% H2O, ensiled for at least 40 days; (ii) 3% NH3, 60% H2O for 30 days at 21°C; (iii) 3% NH3, 60% H2O for 12 h at 90°C; (iv) steamed at 16.2 kg/cm2 and 213°C for 4 min. Ammoniated materials were aerated prior to feeding. All rations were equally supplemented with molasses and soya bean meal while urea was added to treatments (i) and (iv) to increase the crude protein content to at least 12%. Ammoniation at ambient and elevated temperatures increased (P < 0.05) organic matter intake by 30 and 39%, respectively. No difference in intake occurred between the control and steam-treated stovers. However, apparent digestibility of dry matter, organic matter, neutral detergent fibre, acid detergent fibre and cellulose increased (P < 0.05) with all treated stovers. Thermoammoniation produced the greatest (P < 0.05) improvements in digestibility. Improvements in nitrogen retention were slight and non-significant with ammoniated stovers.Thermoammoniation of maize stover with 3% NH3 and 60% H2O for 12 h at 90°C increased the extent of digestion over ambient ammoniation and steam treatment, and is a rapid and effective method of improving the feeding value of low quality roughages.  相似文献   

9.
Hydrothermal pretreatment was performed on the leaves and internodes portions of Alamo switchgrass, Panicum virgatum L., to enhance the digestibility of cellulose towards cellulase. It was observed that extractives free leaves portion provided 18.1% lower pretreatment gravimetrical yield and 33.8% greater cellulose-to-glucose yield than internodes portion. The degree of polymerization (DP) and ultrastructure of cellulose were determined by gel-permeation chromatography and solid-state cross polarization/magic angle spinning 13C NMR experiments. The results suggested that hydrothermal pretreatment hydrolyzed amorphous cellulose and yielded a product enriched in paracrystalline cellulose. Furthermore, the DP of cellulose was reduced to one third of the origin value after hydrothermal pretreatment. The resulting biomass after pretreatment for leaves and internodes has similar cellulose ultrastructure and chemical profiles. The results of the enzymatic hydrolysis studies of cellulose suggest that the reduced DP of cellulose of pretreated switchgrass was an important factor influencing the enhanced digestibility of pretreated switchgrass.  相似文献   

10.
Samples of nine species or types of commercial grass seed straws grown in Oregon were analyzed and treated with anhydrous ammonia in the laboratory. Enzymatic digestibility of treated and untreated materials was determined using commercial cellulase and protease. The mean composition of all nine species/types (based on six each within-group replicates) was: crude protein, 5.4%; NDF, 72.2%; ADF, 43.6%; hemicellulose, 26.4%; cellulose, 34.8%; and lignin, 6.9%. Significant species/type compositional differences were found. From their composition, several of the grass straws appeared to have better nutritional value than most cereal straws. Enzymatic digestibility of all straws was improved by ammoniation (average increase, 62%). Enzymatic digestibility ranged from about 27–42% for untreated materials to 43–66% for NH3-treated products.  相似文献   

11.
Fungal treatment followed by FeCl3 treatment was used to improve saccharification of wood from Populus tomentosa. Combined treatments accumulated lignin and slightly degraded cellulose, whereas almost all hemicelluloses were removed. The white rot fungus, Trametes orientalis, and the brown rot fungus, Fomitopsis palustris, both accompanied by FeCl3 post-treatment resulted in 98.8 and 99.7 % of hemicelluloses loss at 180 °C, respectively, which were over twice than that of hot water pretreatment at the same level. In addition, the solid residue from the T. orientalis-assisted and F. palustris-assisted FeCl3 treatment at 180 °C released 84.5 and 95.4 % of reducing sugars, respectively: 1.4- and 1.6-fold higher than that of FeCl3 treatment alone at the same temperature. Combined treatments disrupted the intact cell structure and increased accessible surface area of cellulose therefore enhancing the enzymatic digestibility, as evidenced by XRD and SEM analysis data.  相似文献   

12.
In vitro cultures of ruminal microorganisms were used to determine the effect of cinnamic acid and vanillin on the digestibility of cellulose and xylan. Cinnamic acid and vanillin depressed in vitro dry matter disappearance of cellulose 14 and 49%, respectively, when rumen fluid was the inoculum. The number of viable Bacteroides succinogenes cells, the predominant cellulolytic organism, was threefold higher for fermentations which contained vanillin than for control fermentations. When xylan replaced cellulose as the substrate, a 14% decrease in the digestibility of xylan was observed with vanillin added; however, the number of viable xylanolytic bacteria cultured from the batch fermentation was 10-fold greater than that of control fermentations. The doubling time of B. succinogenes was increased from 2.32 to 2.58 h when vanillin was added to cellobiose medium, and absorbance was one-half that of controls after 18 h. The growth rate of Ruminococcus albus and Ruminococcus flavefaciens was inhibited more by p-coumaric acid than by vanillin, although no reduction of final absorbance was observed in their growth cycles. Vanillin, and to a lesser extent cinnamic acid, appeared to prevent the attachment of B. succinogenes cells to cellulose particles, but did not affect dissociation of cells from the particles. B. succinogenes, R. albus, R. flavefaciens, and Butyrivibrio fibrisolvens all modified the parent monomers cinnamic acid, p-coumaric acid, ferulic acid, and vanillin, with B. fibrisolvens causing the most extensive modification. These results suggest that phenolic monomers can inhibit digestibility of cellulose and xylan, possibly by influencing attachment of the fibrolytic microorganisms to fiber particles. The reduced bacterial attachment to structural carbohydrates in the presence of vanillin may generate more free-floating fibrolytic organisms, thus giving a deceptively higher viable count.  相似文献   

13.
Seventeen sets of apparent digestibility data derived from 10 experiments, in which both cattle and sheep had been fed on the same hays, were examined. The study was restricted to low-quality hays of less than 60% apparent digestibility of dry matter. On average, digestibility was higher for cattle than for sheep, and the difference was greatest with the samples of lowest digestibility. A linear equation found to describe best the relationship between the digestibility of hays by cattle and sheep was:
y = 0.673 x + 20.3
where y = digestibility of hay to cattle (%) and x = digestibility to sheep (%) (r = 0.843; Sy.x, ± 3.41; standard error of the slope, ± 0.111). This equation may be used to correct apparent digestibility values of 60% or less measured with sheep, or estimated in vitro with the use of sheep standards, if the digestibility data are to be applied to cattle.  相似文献   

14.
《Insect Biochemistry》1987,17(2):277-282
The nitrogenous and carbohydrate components of ryegrass and faeces from larvae of Tipula paludosa Meigen, fed on ryegrass (Lolium perenne L.), were compared. Proteins in ryegrass were efficiently digested and uric acid was the major nitrogenous excretory product. The alkaline midgut (pH 9.1) was considered to enhance the digestibility of hemicellulose, by removing inhibitory acetyl groups, and of cellulose by altering its crystallinity. T. paludosa larvae assimilated 50% of ryegrass cellulose, and 50% of an isolated 14C-labelled cellulose, whereas 86% of hemicellulose was digested.  相似文献   

15.
Plant lignocellulose constitutes an abundant and sustainable source of polysaccharides that can be converted into biofuels. However, the enzymatic digestion of native plant cell walls is inefficient, presenting a considerable barrier to cost-effective biofuel production. In addition to the insolubility of cellulose and hemicellulose, the tight association of lignin with these polysaccharides intensifies the problem of cell wall recalcitrance. To determine the extent to which lignin influences the enzymatic digestion of cellulose, specifically in secondary walls that contain the majority of cellulose and lignin in plants, we used a model system consisting of cultured xylem cells from Zinnia elegans . Rather than using purified cell wall substrates or plant tissue, we have applied this system to study cell wall degradation because it predominantly consists of homogeneous populations of single cells exhibiting large deposits of lignocellulose. We depleted lignin in these cells by treating with an oxidative chemical or by inhibiting lignin biosynthesis, and then examined the resulting cellulose digestibility and accessibility using a fluorescent cellulose-binding probe. Following cellulase digestion, we measured a significant decrease in relative cellulose content in lignin-depleted cells, whereas cells with intact lignin remained essentially unaltered. We also observed a significant increase in probe binding after lignin depletion, indicating that decreased lignin levels improve cellulose accessibility. These results indicate that lignin depletion considerably enhances the digestibility of cellulose in the cell wall by increasing the susceptibility of cellulose to enzymatic attack. Although other wall components are likely to contribute, our quantitative study exploits cultured Zinnia xylem cells to demonstrate the dominant influence of lignin on the enzymatic digestion of the cell wall. This system is simple enough for quantitative image analysis, but realistic enough to capture the natural complexity of lignocellulose in the plant cell wall. Consequently, these cells represent a suitable model for analyzing native lignocellulose degradation.  相似文献   

16.
The article discusses the effect on solubility in cellulolytic enzyme suspensions, digestibility in vitro and crude protein content (F × 6.25) of treating barley straw with various dosages of NH3 (2.6–5.9%), at various temperatures (15–75°C) for various treatment times (1–14 days).An increase in any of the above factors resulted in an increased intensity of treatment, with an increase in temperature of 15°C being equal to an increased NH3-dosage level of 1.5% or prolongation of the treatment time by a factor of 4.5Digestibility in vitro increased with increased intensity of treatment, until a maximum level was obtained. Beyond this point, an increase in NH3-dosage, or especially in temperature, tended to decrease digestibility in vitro. Maximum digestibility could be obtained, for example, with 2.6% NH3, 62°C and 4 days incubation, or 5.9% NH3, 30°C and 3–7 days incubation.Likewise, both solubility in cellulolytic enzyme suspensions and crude protein content increased with increased intensity of treatment, up to a certain level. Thereafter, increased dosing with NH3, higher temperatures or longer incubation times had little or no effect. However, maximum values were obtained with a greater intensity of treatment than the maximum digestibility in vitro, and no tendency towards decreased values was observed.Increased enzyme solubility, beyond that corresponding to maximum digestibility in vitro, was accompanied by an increased rate of fermentation and a decreased content of neutral detergent fibre.Treatment with heat (100°C) and pressure after incubation, to simulate pelleting before evaporation of surplus NH3, was also investigated. Only after the lowest incubation temperatures, however, was there an obvious tendency towards increased digestibility. The enzyme solubility was, on the other hand, very obviously increased. Crude protein content was also slightly increased by the heat- and pressure-treatment.  相似文献   

17.
Experiments were conducted in vitro and in vivo to determine the effects of sulphur (S) supplementation of a good quality fescue hay containing 0.27% total S and a tropical star grass hay containing 0.20% total S. Addition of S was on an isosulphurous basis of either sodium sulphate or D,L-methionine. Cellulose digestion in vitro was improved (P < 0.001) by the addition of 1% urea. Supplementation of forage with 0.05, 0.10 or 0.15% S from either sodium sulphate or methionine also stimulated cellulose digestion in vitro. There were no differences between S sources. The addition of 0.4 or 0.8% nitrate-nitrogen (nitrate-N) (potassium nitrate) depressed (P < 0.05) cellulose digestion in vitro of both hays. No effect of animal adaptation to nitrate was evident. Addition of S partially counteracted the depression in cellulose digestion due to nitrate. Trials were conducted in vivo in which 12 crossbred wether lambs (fescue experiment) or 12 crossbred intact male lambs (star grass experiment) were randomly assigned to one of three treatments: control (forage with no addition of S); forage plus 0.15% S as sodium sulphate; and forage plus 0.15% S as D,L-methionine. Lambs were housed in metabolism crates and each experiment was replicated twice. Dry matter intakes were highest for methionine-supplemented fescue and for S-supplemented star grass, regardless of S source. Dry matter digestibility tended to increase with S addition (fescue experiment) and was significantly higher for S-supplemented star grass. There was a significant increase (P < 0.05) in neutral detergent fibre (NDF) and acid detergent fibre (ADF) digestibility due to supplemental S, regardless of S source. Nitrogen retention, ammonia-N and ruminal volatile fatty acids were unaffected by S supplementation.  相似文献   

18.
Use of markers for the measurement of digestibility is a less labour intensive method than total faecal collection. The objectives of the present study were: (1) to evaluate chromic oxide (Cr2O3), titanium dioxide (TiO2) and acid-insoluble ash (AIA) markers for the calculation of digestibility and (2) to examine the reliability of grab sampling as a technique for measuring digestibility in group-housed animals. For marker comparison, eight entire males were housed in individual metabolism crates and offered a cereal-based diet. Pigs were randomly allotted to treatments for total collection period one, four to the diet with 1 g chromic oxide and 1 g titanium dioxide added per kilogram (Treatment A) and four to the same the diet without marker (Treatment B). During total collection period two, the treatments were reversed. AIA was measured for all animals in crates. For grab sampling study, grouped-housed animals (13–14 per pen) were fed the same cereal-based diet as for marker comparison above and AIA marker was used. Faecal samples were taken from a representative number of animals (minimum eight) in a pen while held in a weighing scales. All feed and faeces samples were analysed for marker content and digestibility. Feed analysis showed 0.93 g/kg of Cr2O3 and 1.02 g/kg of TiO2 added to the diet. Faecal marker recovery was 96, 92.3 and 99.9% (S.E. 2.27) for Cr2O3, TiO2 and AIA, respectively. Mean energy digestibility values were 0.858, 0.848, 0.844 and 0.855 (S.E. 0.003, P<0.01) for total collection, Cr2O3, TiO2, AIA, respectively. Energy digestibility coefficients were 0.852 and 0.861 (S.E. 0.004, P>0.10) for total collection (as measured in marker comparison) and grab sampled animals, respectively. In conclusion, acid-insoluble is a reliable marker for the measurement of digestibility and grab sampling offers a rapid and reliable alternative to the labour intensive metabolism crate method.  相似文献   

19.
A supplement of KH2PO4, MgSO4, CaCl2, trace elements, and thiamine accelerated the initial rate of aspen wood decay by Phanerochaete chrysosporium but did not increase the extent of lignin degradation. Asparagine, casein hydrolysate, and urea supplements (1% added N) strongly inhibited lignin degradation and weight loss. The complex nitrogen sources peptone and yeast extract stimulated lignin degradation and weight loss. Albumen and NH4Cl had intermediate effects. Conversion of [14C]lignin to 14CO2 and water-soluble materials underestimated lignin degradation in the presence of the complex N sources. The highest ratio of lignin degradation to total weight loss and the largest increase in cellulase digestibility occurred during the decay of unsupplemented wood. Rotting of aspen wood by P. chrysosporium gives smaller digestibility increases than have been found with some other white-rot fungi.  相似文献   

20.
Forage digestibility is one of the most important factors in livestock performance. As grasses grow and mature, dry matter increases but they become fibrous with secondary cell wall deposition and lignification of sclerenchyma cells, and forage quality drops. In rice (Oryza sativa), the SECONDARY WALL NAC DOMAIN PROTEIN2 fused with the modified EAR-like motif repression domain (OsSWN2-SRDX) reduces secondary cell wall thickening in sclerenchyma cells. We introduced OsSWN2-SRDX under the control of the OsSWN1 promoter into tall fescue (Festuca arundinacea Schreb.) to increase cell wall digestibility. Of 23 transgenic plants expressing OsSWN2-SRDX, nine had brittle internodes that were easily broken by bending. Their secondary cell walls were significantly thinner than those of the wild type in interfascicular fibers of internodes and in cortical fiber cells between leaf epidermal cells and vascular bundles. The dry matter digestibility increased by 11.8% in stems and by 6.8% in leaves compared with the wild type, and therefore forage quality was improved. In stem interfascicular fibers, acid detergent fiber and acid insoluble lignin were greatly reduced. Thus, the reduction of indigestible fiber composed of cellulose and lignin increased the degradability of sclerenchyma cell walls. OsSWN2-SRDX plants offer great potential in the genetic improvement of forage digestibility.  相似文献   

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