共查询到20条相似文献,搜索用时 15 毫秒
1.
Duy Michael Le Anders Damgaard Nielsen Hanne R. Sørensen Anne S. Meyer 《Bioenergy Research》2017,10(4):1025-1035
Efficient methods for lignin characterisation are increasingly important as the field of lignin valorisation is growing with the increasing use of lignocellulosic feedstocks, such as wheat straw and corn stover, in biorefineries. In this study, we characterised a set of authentic lignin biorefinery samples in situ with no prior purification and minimal sample preparation. Lignin chemical formulas and lignin Fourier transform infrared (FTIR) spectra were extracted from mixed spectra by filtering out signals from residual carbohydrates and minerals. From estimations of C, H and O and adjustment for cellulose and hemicelluloses contents, the average chemical formula of lignin was found to be C9H10.2O3.4 with slight variations depending on the biomass feedstock and processing conditions (between C9H9.5O2.8 and C9H11.1O3.6). Extracted FTIR lignin spectra showed many of the same characteristic peaks as organosolv and kraft lignin used as benchmark samples. Some variations in the lignin spectra of biorefinery lignin residue samples were found depending on biomass feedstock (wheat straw, corn stover or poplar) and on pretreatment severity, especially in the absorbance of bands at 1267 and 1032 cm?1 relative to the strong band at ~1120 cm?1. The suggested method of FTIR spectral analysis with adjustment for cellulose and hemicellulose is proposed to provide a fast and efficient way of analysing lignin in genuine lignin samples resulting from biorefineries. 相似文献
2.
Alan J. McCarthy Alistair Paterson Paul Broda 《Applied microbiology and biotechnology》1986,24(4):347-352
Summary
Thermomonospora mesophila degraded [14C]lignin-labelled wheat lignocellulose to yield high molecular weight water-soluble products and a small amount of 14CO2. Solubilisation of [14C]lignin was found to be extracellular and inducible by growth on lignocellulose (straw) and hemicellulose (xylan), but was not correlated with xylanase or cellulase production.The acid-precipitable product of straw degradation by T. mesophila was found to be a complex of lignin, pentose-rich carbohydrate and protein with some similarity to humic acids. Solid-state 13C-NMR spectra of the dried product were generally similar to those of chemically extracted milled straw lignin but showed an increased content of carbonyl groups.The relationship between degradation and solubilisation of lignin is discussed and a role suggested for actinomycetes in humification and the exploitation of lignocellulose bioconversion. 相似文献
3.
Wood-grown cultures of Daldinia concentrica oxidized a permethylated β-14C-labeled synthetic lignin to 14CO2 and also cleaved a permethylated α-13C-labeled synthetic lignin to give Cα-Cβ cleavage products that were detected by 13C nuclear magnetic resonance spectrometry. Therefore, this ascomycete resembles white-rot basidiomycetes in attacking the recalcitrant nonphenolic structures that predominate in lignin. 相似文献
4.
The effect of different treatments on the enzymatic hydrolysis of furfural residue (FR) was investigated in delignification and structural features. In this case, hot water, ethanol, sodium hydroxide, alkali ethanol, and alkaline hydrogen peroxide solution (AHP) were selected as the delignification solvents. The structure and morphology of the original and treated samples were comparatively studied by diffuse reflectance infrared Fourier transform spectrometry (DRIFT), XRD, SEM, and CP/MAS 13C NMR. After AHP treatment, the ratio of total lignin to cellulose content in FR and the absorbance ratio of lignin to cellulose (A 1508/A 1057) on the sample surface in the DRIFT spectra was reduced from 0.99 to 0.13 and from 0.40 to 0.04, respectively, which resulted in the highest conversion of cellulose to glucose (99.3 %). It was found that the crystallinity index of FR linearly increased with the decrease of total lignin to cellulose ratio. DRIFT analysis indicated that the high lignin content on the sample surface resulted in a low enzymatic hydrolysis efficiency. 相似文献
5.
H. Nadji P.N. Diouf A. Benaboura Y. Bedard B. Riedl T. Stevanovic 《Bioresource technology》2009,100(14):3585-3592
Soda lignin, dioxane lignin and milled lignin were isolated from Alfa grass (Stipatenacissima L.). The physico-chemical characterization of three different lignins: one industrial lignin precipitated from soda spent liquor and two lignin preparations isolated under laboratory conditions from Alfa grass (also know as Esparto grass) was performed. The structures of lignins were studied by three non-destructive (FT-IR, solid state 13C NMR and UV/visible spectroscopy) and two destructive (nitrobenzene oxidation and thermogravimetric analysis) methods. Elemental analysis and the methoxyl content determination were performed in order to determine the C9 formulae for the studied lignins. The total antioxidant capacity of the studied lignins has been determined and compared to commercial antioxidants commonly used in thermoplastic industry. 相似文献
6.
《International biodeterioration & biodegradation》2005,55(3):175-185
Chemical changes of polysaccharides and lignin in Prunus armeniaca decayed by the ascomycete fungus Hypocrea sulphurea were investigated. Solid-state 13C NMR spectra showed that polysaccharides were the main components of fresh and decayed wood. Decomposition of cellulose and hemicellulose by the fungus was minimal although a slight preference for crystalline as compared with amorphous cellulose was recognised. Comparison of the signal intensity of the resonance at 145 ppm in fresh and decomposed wood suggested that the fungus had decomposed tannin constituents. Thermochemolysis with tetramethylammonium hydroxide (TMAH) and product identification by gas chromatography–mass spectrometry revealed that the ratio of syringyl-type (S) units to guaiacyl-type (G) units decreased from 1.8 to 1.1 following fungal attack. Increases in both guaiacyl and syringyl acid-aldehyde ratios (Ad/Al)G, (Ad/Al)S together with an increase from 0.82 to 3.54 in the ratio of methyl 3,4-dimethoxybenzoate to the sum of 1-(3,4-dimethoxyphenyl)-1,2,3-trimethoxypropane (threo and erythro-isomers) ΓG from the decayed wood confirmed oxidative Cα–Cβ cleavage for the mechanism of lignin decay by this ascomycete. 相似文献
7.
Cultural conditions affecting lignin degradation by Phanerochaete chrysosporium in various lignocellulosic materials were studied in comparison to an isolated lignin preparation. With shallow mycelial cultures, the degradation of lignin in wood proceeded more slowly in a 100% O2-atmosphere than in an air atmosphere, indicating that pure oxygen was toxic to the fungus. The organism was able to degrade lignin efficiently even under 30% CO2 and 10% O2 concentrations. Evolution of 14CO2 from labelled lignocellulosic materials was shown not to be representative of total lignin degradation. Addition of glucose to the culture did not affect lignin degradation measured by 14CO2 evolution, whereas lignin degradation measured by Klason lignin method stopped completely (poplar) or slowed considerably (straw). Due to partial depolymerization of lignin to soluble products, measuring only the evolution of 14CO2 results in an underestimation of the total amount of lignin bioaltered. The soluble products from all of the tested lignocellulosic materials and from the isolated lignin had an average molecular weight of about 1,000 and the products could be further fractionated by ion exchange chromatography. The relative amount of these products could be varied from 15 to 45% from the original lignin. 相似文献
8.
Carsten Sievers Teresita MarzialettiTravis J.C. Hoskins Mariefel B. Valenzuela OlartePradeep K. Agrawal Christopher W. Jones 《Bioresource technology》2009,100(20):4758-4765
The composition of solid residues from hydrolysis reactions of loblolly pine wood with dilute mineral acids is analyzed by 13C Cross Polarization Magic Angle Spinning (CP MAS) NMR spectroscopy. Using this method, the carbohydrate and lignin fractions are quantified in less than 3 h as compared to over a day using wet chemical methods. In addition to the quantitative information, 13C CP MAS NMR spectroscopy provides information on the formation of additional extractives and pseudo lignin from the carbohydrates. Being a non-destructive technique, NMR spectroscopy provides unambiguous evidence of the presence of side reactions and products, which is a clear advantage over the wet chemical analytical methods. Quantitative results from NMR spectroscopy and proximate analysis are compared for the residues from hydrolysis of loblolly pine wood under 13 different conditions; samples were treated either at 150 °C or 200 °C in the presence of various acids (HCl, H2SO4, H3PO4, HNO3 and TFA) or water. The lignin content determined by both methods differed on averaged by 2.9 wt% resulting in a standard deviation of 3.5 wt%. It is shown that solid degradation products are formed from saccharide precursors under harsh reaction conditions. These degradation reactions limit the total possible yield of monosaccharides from any subsequent reaction. 相似文献
9.
《Inorganica chimica acta》1988,145(2):273-277
The 13C and 15SN NMR spectra of eleven cis-Fe(S2CNRR′)2(CO)2 complexes, where R and R′ are organic substituents, have been measured at ambient temperature in CDCl3 (0.08–0.16 M). The 13C absorptions for the carbonyl ligands correlate well with the force constants for the CO stretching vibrations in CHCl3 solution. Each of the parameters (13CO absorption and kcis for CO) correlate well with the aqueous solution pKa for+H2NRR′, corrected for the phenyl-containing substituents, high pKa values corresponding to high 13CO absorptions and low kcis CO force constants. [p ]Evidence was found in the 13C NMR spectra for hindered rotation about the CN bond in S2CNC2 in complexes with higher pKa(corr) values and in the 13C spectra of the corresponding thiuram disulfides. [p ]The 15N (natural abundance) NMR spectra for each of the complexes was determined. Each revealed a single sharp absorption in a region of the 15N NMR spectrum which indicates substantial CN double bond character, as one would expect for coordinated dithiocarbamate ligands. 相似文献
10.
Jehle S Hiller M Rehbein K Diehl A Oschkinat H van Rossum BJ 《Journal of biomolecular NMR》2006,36(3):169-177
A simple spectroscopic filtering technique is presented that may aid the assignment of 13C and 15N resonances of methyl-containing amino-acids in solid-state magic-angle spinning (MAS) NMR. A filtering block that selects methyl resonances is introduced in two-dimensional (2D) 13C-homonuclear and 15N–13C heteronuclear correlation experiments. The 2D 13C–13C correlation spectra are recorded with the methyl filter implemented prior to a 13C–13C mixing step. It is shown that these methyl-filtered 13C-homonuclear correlation spectra are instrumental in the assignment of Cδ resonances of leucines by suppression of Cγ–Cδ cross peaks. Further, a methyl filter is implemented prior to a 15N–13C transferred-echo double resonance (TEDOR) exchange scheme to obtain 2D 15N–13C heteronuclear correlation spectra. These experiments provide correlations between methyl groups and backbone amides. Some of the observed sequential 15N–13C correlations form the basis for initial sequence-specific assignments of backbone signals of the outer-membrane protein G. 相似文献
11.
T. K. Kirk E. Schultz W. J. Connors L. F. Lorenz J. G. Zeikus 《Archives of microbiology》1978,117(3):277-285
Culture parameters influencing metabolism of synthetic14C-lignins to14CO2 in defined media have been studied in shallow batch cultures of the ligninolytic wood-destroying HymenomycetePhanerochaete chrysosporium Burds. Study of the effect of O2 concentration in the gas phase above non-agitated cultures indicated essentially complete absence of attack on the lignin polymer at 5% O2 in N2, and a 2- to 3-fold enhancement by 100% O2 as compared to air (21% O2). Agitation of the cultures resulting in the formation of mycelial pellets greatly suppressed lignin decomposition. The optimum culture pH for lignin decomposition was 4 to 4.5, with marked suppression above 5.5 and below 3.5. The source of nutrient nitrogen (NO
3
–
, NH
4
+
, amino acids) had little influence on lignin decomposition, but the concentration of nitrogen was critical; decomposition at 24 mM was only 25–35% of that at 2.4 mM N. Thiamine was the only vitamin required for growth and lignin decomposition. Under the optimum conditions developed, decomposition of 5 mg of synthetic lignin was accompanied by utilization of approximately 100 mg of glucose. The influence of the various culture parameters was analogous for metabolism of synthetic lignin labeled in the ring-,side chain-, and methoxyl carbon atoms. 相似文献
12.
Lignin decomposition is sustained under fluctuating redox conditions in humid tropical forest soils
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Steven J. Hall Whendee L. Silver Vitaliy I. Timokhin Kenneth E. Hammel 《Global Change Biology》2015,21(7):2818-2828
Lignin mineralization represents a critical flux in the terrestrial carbon (C) cycle, yet little is known about mechanisms and environmental factors controlling lignin breakdown in mineral soils. Hypoxia is thought to suppress lignin decomposition, yet potential effects of oxygen (O2) variability in surface soils have not been explored. Here, we tested the impact of redox fluctuations on lignin breakdown in humid tropical forest soils during ten‐week laboratory incubations. We used synthetic lignins labeled with 13C in either of two positions (aromatic methoxyl or propyl side chain Cβ) to provide highly sensitive and specific measures of lignin mineralization seldom employed in soils. Four‐day redox fluctuations increased the percent contribution of methoxyl C to soil respiration relative to static aerobic conditions, and cumulative methoxyl‐C mineralization was statistically equivalent under static aerobic and fluctuating redox conditions despite lower soil respiration in the latter treatment. Contributions of the less labile lignin Cβ to soil respiration were equivalent in the static aerobic and fluctuating redox treatments during periods of O2 exposure, and tended to decline during periods of O2 limitation, resulting in lower cumulative Cβ mineralization in the fluctuating treatment relative to the static aerobic treatment. However, cumulative mineralization of both the Cβ‐ and methoxyl‐labeled lignins nearly doubled in the fluctuating treatment relative to the static aerobic treatment when total lignin mineralization was normalized to total O2 exposure. Oxygen fluctuations are thought to be suboptimal for canonical lignin‐degrading microorganisms. However, O2 fluctuations drove substantial Fe reduction and oxidation, and reactive oxygen species generated during abiotic Fe oxidation might explain the elevated contribution of lignin to C mineralization. Iron redox cycling provides a potential mechanism for lignin depletion in soil organic matter. Couplings between soil moisture, redox fluctuations, and lignin breakdown provide a potential link between climate variability and the biochemical composition of soil organic matter. 相似文献
13.
Oana Dima Kris Morreel Bartel Vanholme Hoon Kim John Ralph Wout Boerjan 《The Plant cell》2015,27(3):695-710
Lignin is an aromatic polymer derived from the combinatorial coupling of monolignol radicals in the cell wall. Recently, various glycosylated lignin oligomers have been revealed in Arabidopsis thaliana. Given that monolignol oxidation and monolignol radical coupling are known to occur in the apoplast, and glycosylation in the cytoplasm, it raises questions about the subcellular localization of glycosylated lignin oligomer biosynthesis and their storage. By metabolite profiling of Arabidopsis leaf vacuoles, we show that the leaf vacuole stores a large number of these small glycosylated lignin oligomers. Their structural variety and the incorporation of alternative monomers, as observed in Arabidopsis mutants with altered monolignol biosynthesis, indicate that they are all formed by combinatorial radical coupling. In contrast to the common believe that combinatorial coupling is restricted to the apoplast, we hypothesized that the aglycones of these compounds are made within the cell. To investigate this, leaf protoplast cultures were cofed with 13C6-labeled coniferyl alcohol and a 13C4-labeled dimer of coniferyl alcohol. Metabolite profiling of the cofed protoplasts provided strong support for the occurrence of intracellular monolignol coupling. We therefore propose a metabolic pathway involving intracellular combinatorial coupling of monolignol radicals, followed by oligomer glycosylation and vacuolar import, which shares characteristics with both lignin and lignan biosynthesis. 相似文献
14.
Tomohiro Kimura Krishna Vukoti Diane L. Lynch Dow P. Hurst Alan Grossfield Michael C. Pitman Patricia H. Reggio Alexei A. Yeliseev Klaus Gawrisch 《Proteins》2014,82(3):452-465
The global fold of human cannabinoid type 2 (CB2) receptor in the agonist‐bound active state in lipid bilayers was investigated by solid‐state 13C‐ and 15N magic‐angle spinning (MAS) NMR, in combination with chemical‐shift prediction from a structural model of the receptor obtained by microsecond‐long molecular dynamics (MD) simulations. Uniformly 13C‐ and 15N‐labeled CB2 receptor was expressed in milligram quantities by bacterial fermentation, purified, and functionally reconstituted into liposomes. 13C MAS NMR spectra were recorded without sensitivity enhancement for direct comparison of Cα, Cβ, and C?O bands of superimposed resonances with predictions from protein structures generated by MD. The experimental NMR spectra matched the calculated spectra reasonably well indicating agreement of the global fold of the protein between experiment and simulations. In particular, the 13C chemical shift distribution of Cα resonances was shown to be very sensitive to both the primary amino acid sequence and the secondary structure of CB2. Thus the shape of the Cα band can be used as an indicator of CB2 global fold. The prediction from MD simulations indicated that upon receptor activation a rather limited number of amino acid residues, mainly located in the extracellular Loop 2 and the second half of intracellular Loop 3, change their chemical shifts significantly (≥1.5 ppm for carbons and ≥5.0 ppm for nitrogens). Simulated two‐dimensional 13Cα(i)? 13C?O(i) and 13C?O(i)? 15NH(i + 1) dipolar‐interaction correlation spectra provide guidance for selective amino acid labeling and signal assignment schemes to study the molecular mechanism of activation of CB2 by solid‐state MAS NMR. Proteins 2014; 82:452–465. © 2013 Wiley Periodicals, Inc. 相似文献
15.
Effects of Nitrogen Supplements on Degradation of Aspen Wood Lignin and Carbohydrate Components by Phanerochaete chrysosporium 总被引:7,自引:7,他引:0
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Ian D. Reid 《Applied microbiology》1983,45(3):830-837
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
16.
A. Rodríguez A. Carnicero F. Perestelo G. de la Fuente O. Milstein M. A. Falcn 《Applied microbiology》1994,60(8):2971-2976
A strain of Penicillium chrysogenum has been isolated from pine forest soils in Tenerife (Canary Islands). This strain was capable of utilizing hydroxylated and nonhydroxylated aromatic compounds, in particular cinnamic acid, as its sole carbon source. In an optimum medium with high levels of nitrogen (25.6 mM) and low levels of glucose (5.5 mM), it was able to decolorize Poly B-411 and to transform kraft, organosolv, and synthetic dehydrogenative polymerisate lignins. After 30 days of incubation, the amount of recovered kraft lignin was reduced to 83.5 and 91.3% of that estimated for uninoculated controls by spectrophotometry and klason lignin, respectively. At the same time, the pattern of molecular mass distribution of the lignin remaining in cultures was changed. The amount of organosolv lignin recovered from cultures was reduced to 90.1 and 94.6% of the initial amount as evaluated by spectrophotometry and klason lignin, respectively. About 6% of total applied radioactivity of O14CH3-organosolv lignin was recovered as 14CO2 after 30 days of incubation, and 18.5% of radioactivity from insoluble O14CH3-organosolv lignin was solubilized. After 26 days of incubation, 2.9% of 14C-β-dehydrogenative polymerisate and 4.1% of 14C-ring-dehydrogenative polymerisate evolved as 14CO2. 相似文献
17.
The solution behavior of the single-stranded CCAAT-containing octamer 1 , d(AGCCAATA), that comprises part of the nuclear factor I (NF-I) recognition site at the origin of replication of human adenovirus has been studied by nmr spectroscopy at 500 and 600 MHz. Proton resonance assignments for 1 were aided by selective 13C enrichment at C1′ of A1 or A5. High-resolution 13C-1H heteronuclear multiple-bond coherence spectra of the 13C-labeled oligomers permitted the selective detection of furanosyl ring protons within each labeled residue due to short- and long-range 13C-1H couplings to the enriched C1′. The resulting assignments provided firm starting points in the interpretation of double quantum filtered correlated spectra, yielding information supplemented by total correlated spectroscopy (TOCSY) and rotating frame nuclear Overhauser effect spectroscopic data to completely assign the 1H-nmr spectrum of 1 and extract 3JHH values for furanose con-formational analysis. Several 13C-1H spin-coupling constants within the 13C-enriched A1 or A5 residues were measured from cross-peak shifts in TOCSY spectra, and their signs determined by inspection of the relative orientations of these shifts. 1H-2-H and 13C-1H spin-couplings both indicate a preference (> 75%) for south (C2′-endo) conformations by the furanosyl rings of 1 . © 1994 John Wiley & Sons, Inc. 相似文献
18.
Selective methyl labeling combined with HMQC spectroscopy that exploits a TROSY effect in 13CH3 spin systems has significantly extended the utility of solution NMR spectroscopy in studies of high molecular weight particles.
Herein we compare the utility of 13CH3- versus 13CHD2-labeling of Ile, Leu, Val probes in supra-molecular systems through quantification of relative signal-to-noise ratios in
optimized spectra of highly deuterated, 13CH3- and 13CHD2-labeled samples of the half proteasome (α7α7, 360 kDa). It is shown that the sensitivity of spectra recorded on Ile, Leu, Val 13CH3-labeled samples is between 1.5 and 2 fold higher than the corresponding data sets obtained on α7α7 with 13CHD2 probes. Thus, labeling of supra-molecules with 13CH3 isotopomers remains the method of choice, but in applications where 13CHD2 moieties are required, sensitivity will in general not be limiting. 相似文献
19.
We studied the dynamics of the stable C isotope ratio (δ13C) of Swida controversa and Fagus crenata leaf litter during decomposition for 35 months with reference to the relative enrichment of the residue by lignin fraction-derived
C. The study was carried out on upper and lower parts of a forest slope in a cool temperate forest in Japan. The enrichment
of lignin fraction-C was associated with a decrease in the δ13C of S. controversa residue. The decrease in δ13C was greater at the lower than the upper site for S. controversa. In contrast, the relative increase in lignin fractions in F. crenata residue was not associated with the changes of δ13C. 13C nuclear magnetic resonance analysis, which revealed the relative decrease in alkyl-C and O-alkyl-C and the relative increase
in aromatic-C and carbonyl-C, provided further evidence for the contribution of the selective preservation of lignin of plant
origin to the increase in the lignin fraction. 相似文献
20.
The consumption rate of chlorine dioxide in the reaction with the residual lignin was studied using measurements of the potential of a redox couple ClO2/ClO 2 ? in an aqueous suspension of lignocellulose powder material. The methodology was developed for the study of reaction kinetics of chlorine dioxide with the residual lignin using the first order reaction model with the initial lignin concentration in the reaction medium varying in the range of (1–17) × 10–4 М at the initial chlorine dioxide concentration of 4.48 × 10–4 М. The monochronic rate constant of the second order reaction of chlorine dioxide with the residual lignin was calculated by the dependence keff(I) = keff(II)[L]0 under the lignin excess conditions, it was 1462 ± 108 М–1 s–1. Considering the initial concentrations of reagents, it was found that, with increasing the degree of lignin conversion Θ from ≈0.27 to 0.54, its reactivity in the interaction with the chlorine dioxide is reduced, and the value of keff(II) decreased from ≈1280 to 900 М–1 s–1, which according to the theory of polychronic kinetics was a manifestation of the kinetic nonequivalence of the various ensembles of macromolecules of the residual lignin. Thus, it was experimentally shown for the first time that residual lignin of lignocellulose powder material had a kinetic nonequivalence in the interaction with chlorine dioxide. 相似文献