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PubMed1983

Isolation of a bacterium capable of degrading peanut hull lignin.

Thirty-seven bacterial strains capable of degrading peanut hull lignin were isolated by using four types of lignin preparations and hot-water-extracted peanut hulls. One of the isolates, tentatively identified as Arthrobacter sp., was capable of utilizing all four lignin preparations as well as extracted peanut hulls as a sole source of carbon. The bacterium was also capable of degrading specifically labeled [C]lignin-labeled lignocellulose and [C]cellulose-labeled lignocellulose from the cordgrass Spartina alterniflora and could also degrade [C]Kraft lignin from slash pine. After 10 days of incubation with [C]cellulose-labeled lignocellulose or [C]lignin-labeled lignocellulose from S. alterniflora, the bacterium mineralized 6.5% of the polysaccharide component and 2.9% of the lignin component.

Journal Article↗

PubMed1984

Degradation of lignin by cyathus species.

The ability of 12 Cyathus species to degrade C-labeled lignin in kenaf was studied. The sum of C released into solution plus C released into the gas phase over a 32-day fermentation period was used to determine average daily rates of lignin biodegradation. Cyathus pallidus. C. africanus, and C. berkeleyanus delignified kenaf most rapidly. C. canna showed the greatest preference for lignin degradation over other plant components, and its rate of lignin degradation was only slightly lower than the three most active species. The apparent ability of fungi to metabolize low-molecular-weight lignin breakdown products correlated well with their overall delignification rates. C. stercoreus metabolized degradation products of lignin from wheat straw better than those from kenaf lignin, based on the amount of low-molecular-weight products left in solution.

Journal Article↗

PubMed1989

Detection of lignin peroxidase and xylanase by immunocytochemical labeling in wood decayed by basidiomycetes.

The white rot fungi used in this study caused two different forms of degradation. Phanerochaete chrysosporium, strain BKM-F-1767, and Phellinus pini caused a preferential removal of lignin from birch wood, whereas Trametes (Coriolus) versicolor caused a nonselective attack of all cell wall components. Use of polyclonal antisera to H8 lignin peroxidase and monoclonal antisera to H2 lignin peroxidase followed by immunogold labeling with protein A-gold or protein G-gold, respectively, showed lignin peroxidase extra-and intracellularly to fungal hyphae and within the delignified cell walls after 12 weeks of laboratory decay. Lignin peroxidase was localized at sites within the cell wall where electron-dense areas of the lignified cell wall layers remained. In wood decayed by Trametes versicolor, lignin peroxidase was located primarily along the surface of eroded cell walls. No lignin peroxidase was evident in brown-rotted wood, but slight labeling occurred within hyphal cells. Use of polyclonal antisera to xylanase followed by immunogold labeling showed intense labeling on fungal hyphae and surrounding slime layers and within the woody cell wall, where evidence of degradation was apparent. Colloidal-gold-labeled xylanase was prevalent in wood decayed by all fungi used in this study. Areas of the wood with early stages of cell wall decay had the greatest concentration of gold particles, while little labeling occurred in cells in advanced stages of decay by brown or white rot fungi.

Journal Article↗

PubMed1994

Lignin-Degrading Enzymes of the Commercial Button Mushroom, Agaricus bisporus.

Agaricus bisporus, grown under standard composting conditions, was evaluated for its ability to produce lignin-degrading peroxidases, which have been shown to have an integral role in lignin degradation by wood-rotting fungi. The activity of manganese peroxidase was monitored throughout the production cycle of the fungus, from the time of colonization of the compost through the development of fruit bodies. Characterization of the enzyme was done with a crude compost extract. Manganese peroxidase was found to have a pI of 3.5 and a pH optimum of 5.4 to 5.5, with maximal activity during the initial stages of fruiting (pin stage). The activity declined considerably with fruit body maturation (first break). This apparent developmentally regulated pattern parallels that observed for laccase activity and for degradation of radiolabeled lignin and synthetic lignins by A. bisporus. Lignin peroxidase activity was not detected in the compost extracts. The correlation between the activities of manganese peroxidase and laccase and the degradation of lignin in A. bisporus suggests significant roles for these two enzymes in lignin degradation by this fungus.

Journal Article↗

PubMed1997

Stabilization of lignin peroxidases in white rot fungi by tryptophan.

Supplementation of various cultures of white rot fungi with tryptophan was found to have a large stimulatory effect on lignin peroxidase activity levels. This enhancement was greater than that observed in the presence of the lignin peroxidase recycling agent veratryl alcohol. Using reverse transcription-PCR, we found that tryptophan does not act to induce lignin peroxidase expression at the level of gene transcription. Instead, the activity enhancement observed is likely to result from the protective effect of tryptophan against H2O2 inactivation. In experiments using a partially purified lignin peroxidase preparation, tryptophan and its derivative indole were determined to function in the same way as veratryl alcohol in converting compound II, an oxidized form of lignin peroxidase, to ferric enzyme, thereby completing the catalytic cycle. Furthermore, tryptophan was found to be a better substrate for lignin peroxidase than veratryl alcohol. Inclusion of either tryptophan or indole enhanced the oxidation of the azo dyes methyl orange and Eriochrome blue black. Stimulation of azo dye oxidations by veratryl alcohol has previously been shown to be due to its enzyme recycling function. Our data allow us to propose that tryptophan stabilizes lignin peroxidase by acting as a reductant for the enzyme.

Azo Compounds↗

PubMed2006

[Spectra and structural analysis of high boiling solvent lignin from Bagasse].

Bagasse high boiling solvent lignin is a polymer prepared by high boiling solvent pulping process. In the IR spectra, the absorbance of HBS lignin at 1700 and 1 328 cm(-1) is present. It is showed that the nonconjugated carbonyl existed. The strong absorbance of UV spectra of HBS lignin is about 201 nm for n-->pi electron transition, which indicates that the HBS lignin is an unsaturated polymer. Judged from the 1H NMR, the syringyl and guaiacyl group in the lignin is present. The element composition and the content of OCH3 group were investigated. The empirical C9-formula of the lignin is C9H9.79O2.58(OCH)0.75 according to dealing with the experiment data. The weight-average molecular weight of the HBS lignin is 2674 g x mol(-1).

English Abstract↗

PubMed2004

Effect of xylan and lignin removal by batch and flowthrough pretreatment on the enzymatic digestibility of corn stover cellulose.

Compared with batch systems, flowthrough and countercurrent reactors have important potential advantages for pretreating cellulosic biomass, including higher hemicellulose sugar yields, enhanced cellulose digestibility, and reduced chemical additions. Unfortunately, they suffer from high water and energy use. To better understand these trade-offs, comparative data are reported on xylan and lignin removal and enzymatic digestibility of cellulose for corn stover pretreated in batch and flowthrough reactors over a range of flow rates between 160 degrees and 220 degrees C, with water only and also with 0.1 wt% sulfuric acid. Increasing flow with just water enhanced the xylan dissolution rate, more than doubled total lignin removal, and increased cellulose digestibility. Furthermore, adding dilute sulfuric acid increased the rate of xylan removal for both batch and flowthrough systems. Interestingly, adding acid also increased the lignin removal rate with flow, but less lignin was left in solution when acid was added in batch. Although the enzymatic hydrolysis of pretreated cellulose was related to xylan removal, as others have shown, the digestibility was much better for flowthrough compared with batch systems, for the same degree of xylan removal. Cellulose digestibility for flowthrough reactors was related to lignin removal as well. These results suggest that altering lignin also affects the enzymatic digestibility of corn stover.

Bioreactors↗

PubMed1996

Growth of Saccharomyces cerevisiae, Rhodotorula rubra and Bullera alba in the presence of beechwood prehydrolyzate-based lignin fractions.

The growth of yeast strains Saccharomyces cerevisiae, Rhodotorula rubra and Bullera alba isolated from natural lake microflora was examined in the presence of prehydrolysis lignin and/or its water-soluble derivative. The stimulation effect of the water-soluble lignin derivative was higher in comparison with that of unmodified lignin. The structural changes of the lignin macromolecule by the yeasts determined by IR spectroscopy indicate oxidative degradation and demeth(ox)ylation similar to that found with lignin-degrading hyphal fungi. The results indicate a partial utilization of lignin by the yeasts as carbon source.

Biodegradation, Environmental↗

PubMed2005

Phyto-availability and speciation change of heavy metals in soils amended with lignin as micro-fertilizer.

Lignin is a primary byproduct from the black liquor treatment in paper making industries, its application as micro-fertilizer in agricultural land might provide a promising alternative to sewage discharge. However, application of such a micro-fertilizer might affect the soil properties and result in soil pollution. In this study, the effects of lignin application on phyto-availability and speciation change of heavy metals in soils were investigated. Greenhouse experiments showed that lignin application improved the growth of winter wheat (Triticum aestivum L.) in all three soils investigated. The increase of the biomass for wheat shoot was 59.7%, 39.8% and 12.3% for Beijing soil, Jiangxi soil and Dongbei soil, respectively. In contrast, lignin amendment decreased the concentrations of heavy metals in wheat shoots from 2.2% to 61.0%. Sequential extraction procedure of a three-step BCR was used to investigate the fraction distribution. The extractable fractions were specified as fraction B1: water soluble, exchangeable and carbonate bound or weakly specifically adsorbed; B2: Fe-Mn oxide bound; B3: organic matter and sulfide bound. The results showed that lignin application led to the redistribution of heavy metals in each fraction. Generally, heavy metals decreased in B1 and B2 fractions and increased in B3 fraction. Upon the results short-term application of lignin in agricultural land not only improves the growth of wheat but also reduces the phyto-abailability of heavy metal in wheat.

Biomass↗

PubMed2002

The influence of lignin content and temperature on the biodegradation of lignocellulose in composting conditions.

The aim of this research was to study the influence of lignin content and composting temperature on the biodegradation of lignin-containing pulp and paper products in a controlled composting test (European standard prEN 14046). Lignin reduced the biodegradation of the samples, and there was a linear correlation between the lignin content and the biodegradation of pulp and paper products at 58 degrees C. The influence of incubation temperature (35, 50 and 58 degrees C) on biodegradation was studied using bleached kraft paper containing 0.2 wt% lignin and mechanical pulp (stone-ground wood) containing 24-27 wt% lignin. Mechanical pulp biodegraded better at lower temperatures, while kraft paper biodegraded well at all three temperatures. Microbial activity was evaluated by measuring CO(2) evolution and the change in ATP content, and fungal biomass by measuring the ergosterol content during the composting experiments. Kraft paper strongly increased microbial activity during the controlled composting test, but the activity returned to the background level at the end of the composting test. The proportion of sample carbon converted to microbial biomass carbon was considerably higher at lower incubation temperatures. Changes in microbial community structure during biodegradation of mechanical pulp and kraft paper at 50 degrees C were studied by the PCR-based technique denaturing gradient gel electrophoresis. Changes in the microbial community were observed during the intensive degradation phase of kraft paper.

Bacteria↗

PubMed2001

Biodegradation of radiolabelled synthetic lignin (14C-DHP) and mechanical pulp in a compost environment.

Mineralization of radioactive synthetic lignin (14C-DHP) was studied in a compost environment at 35, 50 and 58 degrees C. Compost samples were successively extracted with water, dioxane and alkali, and the molecular weight distribution of some extracts was determined by gel permeation chromatography (GPC). Biodegradation of lignin-containing spruce groundwood (SGW) and pine sawdust was concurrently determined in controlled composting tests by measuring evolved CO2. The temperatures were the same as in the 14C-DHP mineralization experiment and bleached kraft paper, with a lignin content of 0.2%, was used as a reference. The mineralization of 14C-DHP was relatively high (23-24%) at 35 degrees C and 50 degrees C, although the mixed population of compost obviously lacks the most effective lignin degraders. At 58 degrees C the mineralization of 14C-DHP, as well as the biodegradation of SGW and sawdust, was very low, indicating that the lignin-degrading organisms of compost were inactivated at this temperature. SGW was poorly biodegradable (<40%) in controlled composting tests compared with kraft paper (77-86%) at all temperatures, which means that lignin inhibits the degradation of carbohydrates. During the incubation, water-soluble degradation products, mainly monomers and dimers, and the original 14C-DHP were either mineralized or bound to humic substances. A substantial fraction of 14C-DHP was incorporated into humin or other insolubles.

Biodegradation, Environmental↗

PubMed2006

Raman imaging to investigate ultrastructure and composition of plant cell walls: distribution of lignin and cellulose in black spruce wood (Picea mariana).

A detailed understanding of the structural organization of the cell wall of vascular plants is important from both the perspectives of plant biology and chemistry and of commercial utilization. A state-of-the-art 633-nm laser-based confocal Raman microscope was used to determine the distribution of cell wall components in the cross section of black spruce wood in situ. Chemical information from morphologically distinct cell wall regions was obtained and Raman images of lignin and cellulose spatial distribution were generated. While cell corner (CC) lignin concentration was the highest on average, lignin concentration in compound middle lamella (CmL) was not significantly different from that in secondary wall (S2 and S2-S3). Images generated using the 1,650 cm(-1) band showed that coniferaldehyde and coniferyl alcohol distribution followed that of lignin and no particular cell wall layer/region was therefore enriched in the ethylenic residue. In contrast, cellulose distribution showed the opposite pattern-low concentration in CC and CmL and high in S2 regions. Nevertheless, cellulose concentration varied significantly in some areas, and concentrations of both lignin and cellulose were high in other areas. Though intensity maps of lignin and cellulose distributions are currently interpreted solely in terms of concentration differences, the effect of orientation needs to be carefully considered to reveal the organization of the wood cell wall.

Acrolein↗

PubMed2006

Involvement of AtLAC15 in lignin synthesis in seeds and in root elongation of Arabidopsis.

Laccase, EC 1.10.3.2 or p-diphenol:dioxygen oxidoreductase, has been proposed to be involved in lignin synthesis in plants based on its in vitro enzymatic activity and a close correlation with the lignification process in plants. Despite many years of research, genetic evidence for the role of laccase in lignin synthesis is still missing. By screening mutants available for the annotated laccase gene family in Arabidopsis, we identified two mutants for a single laccase gene, AtLAC15 (At5g48100) with a pale brown or yellow seed coat which resembled the transparent testa (tt) mutant phenotype. A chemical component analysis revealed that the mutant seeds had nearly a 30% decrease in extractable lignin content and a 59% increase in soluble proanthocyanidin or condensed tannin compared with wild-type seeds. In an in vitro enzyme assay, the developing mutant seeds showed a significant reduction in polymerization activity of coniferyl alcohol in the absence of H(2)O(2). Among the dimers formed in the in vitro assay using developing wild-type seeds, 23% of the linkages were beta-O-4 which resembles the major linkages formed in native lignin. The evidence strongly supports that AtLAC15 is involved in lignin synthesis in plants. To our knowledge, this is the first genetic evidence for the role of laccase in lignin synthesis. Changes in seed coat permeability, seed germination and root elongation were also observed in the mutant.

Arabidopsis↗

PubMed2004

On the relationships between leaf-litter lignin and net primary productivity in tropical rain forests.

We investigated if tropical rainforest trees produced more-lignified leaves in less productive environments using forests on Mount Kinabalu, Borneo. Our investigation was based on two earlier suggestions that slower litter decomposition occurs under less productive forests and that trees under resource limitation invest a large amount of carbon as lignin as a defense substance to minimize the loss from herbivores. When nine forests at different altitudes (700-3100 m) and soil conditions (derived from sedimentary or ultrabasic rocks) but with the same gentle relief position were compared, the concentrations of leaf-litter lignin were positively correlated with litterfall rates and leaf-litter nitrogen concentrations. These patterns would be reinforced in intact leaves if the effects of resorption at the time of leaf shedding were taken into account, because greater magnitude of resorption of mobile elements but not of lignin would occur in less productive environments (i.e. dilution of lignin in intact leaves). These results did not support earlier suggestions to explain the variation of leaf-litter lignin. Instead, we suggest that lower lignin contents are adaptive to recycle minerals without retarding decomposition in less productive environments.

Altitude↗

PubMed1993

Lignin-degrading peroxidases of Phanerochaete chrysosporium.

Lignin and manganese peroxidases are secreted by the basidiomycete Phanerochaete chrysosporium during secondary metabolism. These enzymes play major roles in lignin degradation. The active site amino acid sequence of these lignin-degrading peroxidases is similar to that of horseradish peroxidase (HRP) and cytochrome c peroxidase (CcP). The mechanism by which they oxidize substrates also appears to be the similar. pH has a similar effect on lignin peroxidase compound I formation as on HRP or CcP; however, the pKa controlling compound I formation for lignin peroxidase appears to be much lower. Lignin-degrading peroxidases are able to catalyze the oxidation of substrates with high redox potential. This unique ability is consistent with a heme active site of low electron density, which is indicated by high redox potential.

Amino Acid Sequence↗

PubMed1992

Reversible binding of the cooked food mutagen MeIQx to lignin-enriched preparations from wheat bran.

The binding of the mutagen 3,8-dimethyl-3H-imidazo[4,5-f]quinoxaline-2-amine (MeIQx) to various fibre preparations from wheat bran was studied. The physical structures of wheat bran and lignin-enriched preparations were determined by scanning electron microscopy. With increasing mutagen concentration from 0.5-16 micrograms/ml, the fraction of MeIQx bound to cellulase-treated lignin was nearly constant, for a certain lignin density. The binding between cellulase-treated lignin and MeIQx was reversible. Incubation temperature influenced the rate at which the equilibrium between lignin and MeIQx was established, but had less effect on the equilibrium itself. With increasing fibre densities and a constant mutagen concentration, complete binding was apparently reached at a high fibre density. This was illustrated by plotting the data according to Scatchard. Increased binding of the MeIQx was obtained with increased enrichment of lignin in different fibre preparations.

Dietary Fiber↗

PubMed2006

Characterization of lignin isolated from some nonwood available in Bangladesh.

Lignins isolated from cotton stalks, jute stick and dhaincha by acidolytic dioxane were characterized using alkaline nitrobenzene oxidation, elemental analysis, methoxyl analysis and molecular weight analysis and UV, IR (1)H NMR spectroscopy. The C(9) formulas for cotton stalks, jute stick and dhaincha (Sesbania aculeata) lignin were C(9)H(9.36)O(4.50)(OCH(3))(1.23), C(9)H(9.02)O(4.57)(OCH(3))(1.35) and C(9)H(8.88)O(4.65)(OCH(3))(1.50), respectively. All three lignins were of the guaiacyl-syringyl type. Cotton stalks lignin contained more p-hydroxy phenyl unit than dhaincha and jute stick lignins as observed by alkaline nitrobenzene oxidation products. The beta-O-4 units in these nonwood lignins had predominately erythro stereochemistry type.

Bangladesh↗

PubMed2006

Lignin--from natural adsorbent to activated carbon: a review.

The present review compiles the work done over the last few decades on the use of lignin and lignin-based chars and activated carbons as adsorbents for the removal of substances from water and focuses on the utilisation of lignin as adsorbent, its conversion to chars and activated carbons and the use of these materials as adsorbents. Moreover, the review also examines the textural and surface chemical properties of lignin-based activated carbons. The work so far carried out indicates that lignin is relatively non-reactive and probably the component of lignocellulosic precursors primarily responsible for the microporosity of activated carbons. Under appropriate conditions of activation it is possible to obtain materials with surface areas and pore volumes approaching 2000 m(2)g(-1) and 1cm(3)g(-1), respectively, and these materials have capacities for the aqueous phase adsorption of metallic pollutants that are comparable to those of commercial activated carbons. Relatively little work has so far been published and there is considerable scope for more detailed studies on the preparation, characterisation and adsorption applications of lignin-based activated carbons.

Adsorption↗