Lignin Loss Research Articles

Isolation and characterization of cellulose nanofibers from Agave gigantea by chemical-mechanical treatment

Nanocellulose is a renewable and biocompatible nanomaterial that evokes much interest because of its versatility in various applications. This study reports the production of nanocellulose from Agave gigantea (AG) fiber using the chemical-ultrafine grinding treatment. Chemical treatment (alkalization and bleaching) removed non-cellulose components (hemicellulose and lignin), while ultrafine grinding reduced the size of cellulose microfibrils into nanocellulose. From the observation of Transmission Electron Microscopy, the average diameter of nanocellulose was 4.07 nm. The effect of chemical-ultrafine grinding on the morphology and properties of AG fiber was identified using chemical composition, Scanning Electron Microscopy, X-ray Diffraction, Fourier Transform Infrared, and Thermogravimetric Analysis. The bleaching treatment increased the crystal index by 48.3% compared to raw AG fiber, along with an increase in the cellulose content of 20.4%. The ultrafine grinding process caused a decrease in the crystal content of the AG fiber. The crystal index affected the thermal stability of the AG fiber. The TGA results showed that AG fiber treated with bleaching showed the highest thermal stability compared to AG fiber without treatment. The FTIR analysis showed that the presence of CH vibrations from the ether in the fiber. After chemical treatment, the peaks at 1605 and 1243 cm−1 disappeared, indicating the loss of lignin and hemicellulose functional groups in AG fiber. As a result, nanocellulose derived from AG fiber can be applied as reinforcement in environmentally friendly polymer biocomposites.

LIGNOCELLULOSE WASTE VALORIZATION BY AN ENZYMATIC COCKTAIL OF P. ERYNGII AND P. PULMONARIUS

The present study aimed to characterize Pleurotus eryngii and P. pulmonarius ligninolytic enzymes and to determine their potential for polymer degradation in common agroforestry residues. The peak of laccase activity (36052.33 U L-1) was observed after P. pulmonarius cultivation on oak sawdust. The maximal Mn-dependent peroxidase activity was reached by P. eryngii (2511.36 U L-1), while the highest level of versatile peroxidase activity was noted in P. pulmonarius (3053.03 U L-1), after fermentation of corn stalks. The highest level of lignin loss (46.28%) was achieved after cultivation of P. pulmonarius on corn stalks, but the most selective degradation of lignocellulose polymers was observed after P. eryngii cultivation on wheat straw. The obtained results lead to the conclusion that the studied P. eryngii and P. pulmonarius strains are good producers of ligninolytic enzymes and effective and selective depolymerizers of agroforestry residues, and therefore their use would be beneficial in numerous environmentally friendly technologies.

Combined effect of olive pruning residues and spent coffee grounds on Pleurotus ostreatus production, composition, and nutritional value.

No previous study assessed the combined effect of olive pruning residues (OLPR) and spent coffee grounds (SCG) on P. ostreatus production and nutritional value. The aim of this study was to determine the capacity of P. ostreatus to degrade lignocellulosic nature of combined OLPR and SCG as well as their resultant nutrient composition. A complete randomized design was adopted with five treatments: S1:100%wheat straw (WS) (control), S2:33%WS+33%SCG+33%OLPR,S3:66%WS+17%SCG+17%OLPR,S4:17%WS+66%SCG+17%OLPR, and S5:17%WS+17%SCG+66%OLPR, and ten replicates per treatment. Substrate’s and mushroom’s composition were analyzed on chemical scale, including fatty acids and heavy metals profiles, following international standards. Only S1, S2, and S3 were productive, with comparable biological yield, economical yield, and biological efficiency. Organic matter loss decreased with increasing proportions of OLPR and SCG. Percentage lignin loss was higher in S1 than in S2 and S3 (53.51, 26.25, and 46.15% respectively). Mushrooms of S3 had some enhanced nutritional attributes compared to control: decrease in fat, increase in protein, increase in monounsaturated fatty acids, and lower zinc accumulation. Lead was less accumulated in S2 than S1 mushrooms. Sodium content of mushroom decreased in S2 and S3. The latter substrates yielded mushrooms with lower polyunsaturated fatty acids (PUFA) and higher saturated fatty acids (SFA) contents. All mushrooms had a valuable PUFA/SFA. This study suggests using OLPR and SCG in low proportions as nutritional supplements to the commercial wheat straw.

The Effect of Alkali and Fumigation Treatments on King Pineapple Fiber Properties and Interfacial Bonding of King Pineapple Fiber/Unsaturated Polyester on Microcrystalline Cellulose Reinforced Composite

This study aims to determine and compare the effect of alkaline and fumigation treatment on the properties of King pineapple fibers (KPF) and the interfacial bond between King pineapple fibers/ unsaturated polyester and microcrystalline cellulose. Chemically, King pineapple fiber was extracted and dried at room temperature. The fiber was made using the alkaline method by soaking in 5% NaOH for 4 hours, 6 hours, 8 hours, and 10 hours. The fumigation treatment method was carried out for 0 hours, 4 hours, 8 hours, and 12 hours. The single fiber tensile strength test results showed an increase of 51.99% after the fumigation treatment and 59.62 % after the alkaline treatment. The increase in interface shear strength (IFSS) was 32.12% after fumigation treatment and 47.38% after alkaline treatment. The increase in fiber tensile strength and interfacial shear strength (IFSS) is caused by the loss of hemicellulose, pectin, lignin, and other impurities. These results indicate that the alkaline treatment is still better than the fumigation treatment.

Litter decomposition in European coniferous and broadleaf forests under experimentally elevated acidity and nitrogen addition

Atmospheric sulfur (S) and nitrogen (N) deposition has impacted many regions across the Northern Hemisphere inducing acidification and eutrophication of terrestrial ecosystems. However, acidification and eutrophication processes may differently impact litter decomposition and thus soil carbon (C) dynamics. We performed a field soil chemistry manipulation in two mountainous temperate forest stands (Picea abies and Fagus sylvatica) historically affected by acid (S and N) deposition. In each stand, four treatments were established: control, acid addition (H2SO4 – 50 kg S·ha− 1·year− 1), N addition (NH4NO3 – 50 kg N·ha− 1·year− 1) and their combination. In fourth year of manipulation, we established litter decomposition experiment. Litter bags of contrasting quality and origin (green tea, rooibos tea, spruce needles and beech leaves), in total 1536 samples, were buried below the organic layer and left to decompose up to 24 months. Retrieved samples were analysed for mass loss, C/N, and concentration of CuO oxidation lignin. Data were complemented by monitoring soil water pH and soil CO2 efflux. Acid additions decreased soil water pH, soil respiration and suppressed decomposition of the high-quality litter (green tea) in both stands, whereas mass loss of remaining litter was reduced only in the spruce stand. Nitrogen treatments, when coupled with decreasing soil water pH, constrained needle decomposition in the naturally more acidic spruce stand. Our study demonstrates a suppressing effect of soil acidity on decomposition processes and soil C dynamics. The effect of N addition, as a nutrient, was insignificant, likely because of previous ecosystem adaptation to historical N loadings.

Signatures of an abiotic decomposition pathway in temperate forest leaf litter

Photodegradation helps explain why leaf litter mass loss rates are comparable between mesic environments and drylands, despite water availability limiting decomposer activity in drylands. With photodegradation, light energy directly mineralizes photoreactive organic molecules such as lignin, which contrasts with biotically-driven decomposition where lignin persists in decomposing leaf litter relative to other compounds. Photodegradation of leaf litter has largely been studied in dryland systems, but whether it occurs in mesic, deciduous forest systems is uncertain. As such, we examined potential photodegradation in maple and oak litter in the Southern Appalachian Mountains (USA) during the non-growing season, when newly fallen leaves are exposed to maximum solar radiation without deciduous canopies. The proportion of oxidized lignin in the leaf litter relative to other carbon compounds decreased with maximum solar radiation during the non-growing season. With a closed canopy, however, the proportion of total lignin relative to other compounds in the leaves increased. This pattern was particularly strong for the syringyl- S6 and guaiacyl-G6 lignin monomers. The relative proportion of S6 and G6 in the litters was reduced by 10–65% in the first 5 months. The largest reductions in lignin occurred on south-facing mountain slopes where solar radiation was highest (relative to north-facing slopes) in the Northern Hemisphere. Overall, however, the changes in lignin did not alter cumulative litter mass lost. Our results suggest that photodegradation promotes the transformation and relative loss of lignin in the early stages of litter decomposition in mesic deciduous forests.

The acetyl bromide lignin method accurately quantitates lignin in forage

The acetyl bromide lignin (ABL) has been shown to provide a similar relationship between lignin concentration and fiber degradability for grasses and legumes. In contrast, the acid detergent lignin (ADL) method results in different regression equations for grasses and legumes with a larger slope for grasses. The difference may be due to solubilization and loss of lignin in the grasses during the acid detergent fiber (ADF) procedure. While ADL and ABL values for legumes were about the same, ADL values for grasses were about half of those for ABL, supporting the theory that lignin was lost in grasses in the ADL method. We estimated this loss at about 60 %, so multiplying the ADL in grasses by 2.4 would yield the actual lignin concentrations. Applying this multiplier to ADL in grasses, but not in legumes, resulted in analogous regression lines for forage degradability, that were similar to those obtained with the ABL method. The nutritional entity ABL behaves uniformly for grasses and legumes and may properly determine measures of lignin, allowing further research on the mechanisms by which lignin acts as a barrier to enzymatic degradation of forage cell wall polysaccharides, which may provide information on the potential nutritive value of specific plants for herbivores.

EFFECT OF REACTION TIME AND SODIUM HYDROXIDE CONCENTRATION ON DELIGNIFICATION AND ENZYMATIC HYDROLYSISOF BREWER’S SPENT GRAIN FROM WO BRAZILIAN BREWERS

Brazil, being one of the main beer producers, generates brewer’s spent grain as a main by-product of this industry, which is mainly composed of cellulose, hemicelluloses, lignin and extractives. The alkaline pretreatment of brewer’s spent grain received from two breweries is studied in this work, namely breweries Imperial (B1) and Colombina (B2). Factorial design (22) was realized with three experiments at the central point: contact time (30, 60, 90 min) and NaOH concentration (4%, 6%, 8%). It was found that the presence of extractives causes interference in the characterization of the material. The delignification process allowed obtaining materials with lower lignin percentages when higher NaOH concentrations were used, reaching percentages of lignin loss with values between 85-95%, in both materials, but for these conditions, the losses of cellulose were considerable – of 35-43%. Enzymatic hydrolysis of the pretreated materials achieved conversions greater than 70%, emphasizing that the greatest conversions were obtained with material B1, where almost the whole cellulose was hydrolyzed.

Pretreatment of Tropical Lignocellulosic Biomass for Industrial Biofuel Production : A Review

As energy demand increase with human activities, the practical solution this far is to use more fossil-based energy to meet those demand. Diminishing fossil energy reserves that can cause crisis and also the increasing price of fossil energy are the main challenges for the world, and are a big problem for developing countries. Environmental factors, sustainability, and national resilience are the main considerations for replacing fossil energy with non-fossil alternative energy such as solar energy, hydro energy, wind energy and biomass or biofuel energy. Lignocellulosic biomass which is a waste from the agricultural industry, livestock industry waste, solid waste and other materials is the most abundant source of biomass that can be used to produce biofuels. In Indonesia, the most abundant sources are palm oil empty fruit bunches, corn stover, rice husks, rice straw, sugarcane bagasse, and coconut husk. Utilization of lignocellulosic biomass to be converted into energy requires pretreatment to change interactions between components found in plant cell walls. Pretreatment can remove physical and chemical barriers that make lignocellulosic material difficult to react and difficult to access by enzymes for the hydrolysis process. While the hydrolysis process is a vital stage in the biochemical process from lignocellulose to sugar-based energy conversion. By comparing several pretreatments based on glucose yield and other technical factors, it can be concluded that steam explosion is the best pretreatment by the reason of not requiring a small sizing on the biomass so that it is more energy efficient; not use chemicals; low water content causes energy saving; no degradation of cellulose and lignin so that sugar yields are higher and lignin can be recovered; and also the results of hemicellulose degradation can be separated by leaching and having economical value. The mechanism of the process that occurs in the steam explosion pretreatment is that high temperatures cause the release of acetyl groups on the hemicellulose structure which causes autohydrolysis to degrade hemicellulose; high temperatures cause steam to be acidic and degrade hemicellulose and hydrolyze some cellulose; sudden pressure drop causes redistribution of the lignin structure so that the lignin structure is not damaged and can be recovered; the loss of lignin and hemicellulose which blocks enzyme access to cellulose causes an increase in glucose yield during the enzymatic hydrolysis process. The steam explosion pretreatment method is not effective for hard biomass, but that raw material is more effectively processed using the alkaline method.

Characterizing Fungal Decay of Beech Wood: Potential for Biotechnological Applications

The biotechnological potential of nine decay fungi collected from stored beech logs at a pulp and paper factory yard in Northern Iran was investigated. Beech blocks exposed to the fungi in a laboratory decay test were used to study changes in cell wall chemistry using both wet chemistry and spectroscopic methods. Pleurotus ostreatus, P. pulmonarius, and Lentinus sajor-caju caused greater lignin breakdown compared to other white-rot fungi, which led to a 28% reduction in refining energy. Trametes versicolor caused the greatest glucan loss, while P. ostreatus and L. sajor-caju were associated with the lowest losses of this sugar. Fourier transform infrared spectroscopy (FTIR) analyses indicated that white-rot fungi caused greater lignin degradation in the cell walls via the oxidation aromatic rings, confirming the chemical analysis. The rate of cellulose and lignin degradation by the T. versicolor and Pleurotus species was high compared to the other decay fungi analyzed in this study. Based on the above information, we propose that, among the fungi tested, P. ostreatus (27.42% lignin loss and 1.58% cellulose loss) and L. sajor-caju (29.92% lignin loss and 5.95% cellulose loss) have the greatest potential for biopulping.

Reduction in lignin peroxidase activity revealed by effects of lignin content in urea crosslinked starch under aerobic biodegradation in soil

This study characterized the lignin peroxidase (LiP) activity of soil via an enzyme assay to determine the reaction rates and activation energies for 5 wt%, 10 wt%, 15 wt%, and 20 wt% lignin loads in urea crosslinked starch biocomposites. The results revealed that a mixed mode of LiP inhibition occurred after the soil was mixed with these biocomposites with different loads of lignin. Loading of lignin at 5 wt% and 10 wt% lignin resulted in higher values of catalytic activity of LiP: -39.58 and 49.14 µM h-1 g-1 soil, respectively. In comparison, with higher loading of lignin at 15 wt% and 20 wt%, decreases in the catalytic activity of LiP were found and were 28.72 to 37.25 µM h-1 g-1 soil, respectively. The activation energy of LiP increased approximately 1.11- to 1.22-fold when 15 and 20 wt% of lignin was loaded in biocomposites. Research findings established the possibility of unfavorable binding of the LiP to lignin with an increase in the load of lignin, possibly due to the complex structure of intact lignin and presence of inhibitory biodegradation products of lignin accumulates during lignin biodegradation in biocomposites. It was concluded that higher lignin contents (15 wt% and 20 wt%) were effective in reducing the activity of the soil LiP. Hence, higher lignin content possibly protects against losses of lignin, while acting as a filler in the formulation of biocomposites.

The Effects of Temperature and Mineral Nitrogen and Phosphorus on the Decay Processes and Composition of Soil–Bark Substrates

The bark of coniferous trees (BCT) is an essential component of the litter in boreal forests. The effects of temperature and mineral additives (N and P) on the rate of BCT decomposition (DecR), its constant (k), total loss of C–CO2, and the changes in BCT chemical composition are assessed in a long-term (12 months) laboratory experiment with soil–bark substrates (SBSs) using three contrasting temperatures (2, 12, and 22°C) and sufficient moisture. The temperature coefficient (Q10) for the mean DecR during the experiment varies from 1.1 to 2.5 depending on temperature range and SBS composition. The effect of temperature was the most pronounced during the first and second months of the experiment, explaining 47% of the DecR variation. At later stages of the experiment, the SBS composition affected by the addition of mineral N and P compounds is the key factor influencing the BCT decomposition; it explains 18–63% of the DecR variance. The maximum losses of C–CO2 (158–187 g С/(kg bark), or 34–41% of the initial С content) are observed at 22°C. Irrespectively of the temperature, the most significant loss of ethanol-soluble compounds (56–64%) is recorded in the variant with the mineral N additive, whereas the cellulose content most significantly decreases (by 64–69%) in the variant with combined application of N and P and is almost independent of temperature. The loss of lignin was insignificant, amounting to only 3–12% of its initial content. The addition of mineral N and P is a key factor stimulating the BCT decomposition, considerably shortening the decomposition time and improving the quality of the resulting substrates.

Spent coffee grounds influence on Pleurotus ostreatus production, composition, fatty acid profile, and lignocellulose biodegradation capacity

ABSTRACT The capacity of Pleurotus ostreatus to degrade the lignocellulose of spent coffee grounds (SCG) and its resultant nutrient composition is not yet studied. The study tested four SCG/wheat straw mixtures, containing 0, 33, 67, or 100% SCG. Initial lignin content was higher, and lignin loss was lower in mixtures containing SCG, compared to control revealing lower substrate degradation. Biological yield was negatively correlated with initial lignin content, and positively with the lignin loss from substrates. The nutritional value of mushrooms was improved by a general increase in carbohydrates, a decrease in sodium content with 33% and 67% SCG, and lower fat content with 33% SCG. Polyunsaturated fatty acids of mushrooms (PUFA) increased with 67% SCG; while saturated ones (SFA) increased with 33 and 67% SCG. All mushrooms had a close PUFA/SFA, ranging between 7.4 and 8.1. The study suggests using SCG as a nutritional supplement to the commercial wheat straw.

Foliar Cellulose and Lignin Degradation of Two Dominant Tree Species in a Riparian Zone of the Three Gorges Dam Reservoir, China.

The riparian zone can affect the degradation of foliar cellulose and lignin by changing the hydrological gradient of the foliage decomposition environment. However, their degradation dynamics during the process of foliage decomposition remain unclear in mixed plantation forests in a riparian zone. Herein, we explored degradation of cellulose and lignin for two dominant riparian species, bald cypress [Taxodium distichum (L.) Rich.] and Chinese willow (Salix matsudana Koidz.), and a combined treatment with equal proportions of foliar mass of these species, involving three water treatments [no submergence (CK), shallow submergence (SS), and deep submergence (DS)] in a riparian zone of the Three Gorges Dam Reservoir (TGDR), China. Throughout an entire year’s incubation, the degradation of cellulose and lignin was 55.57–97.76% and 79.87–93.82%, respectively. In the early stage of decomposition (i.e., the first 30 days), cellulose and lignin were rapidly degraded, and the mass loss of cellulose and lignin in water environments (SS and DS) was greater than that in a non-flooded environment (CK) regardless of the foliage type. The degradation of cellulose and lignin was mainly related to the quality of the leaf litter (as indicated by the concentrations of cellulose and lignin, and the contents of C, N, and P), decomposition period, and local environmental factors (temperature, water gradients, and dissolved oxygen). Our results will provide a clear insight into the material cycling process in a riparian zone of the TGDR and similar ecosystems in other regions.

Effect of Temperature on the Intensity of the Biogenic Decomposition of Aspen Bark

Under temperate climatic conditions, temperature is a key abiotic factor that controls the decomposition of coarse woody debris including bark. Using aspen bark (AB), we have carried out a 12-month laboratory experiment at three contrasting temperatures (2, 12, and 22°C) and constant sufficient moisture to quantify the temperature effect on the decomposition rate (DecR) and decay constant (k) of aspen bark. The effect of temperature on the total loss of C–CO2 and changes in the chemical composition of AB throughout the experiment are also estimated. An increase in the incubation temperature from 2 to 12°C and from 12 to 22°C induces a similar increase in the average (over 12 months) value of the DecR: the Q10 values are 1.30 and 1.41 in these temperature intervals, respectively. The most significant effect of temperature on the DecR dynamics is revealed during the 1st and 2nd months of the experiment. The maximum losses of C–CO2 (284 ± 16 mg C g bark–1, or 55.2 ± 3.2% of the initial C content) are observed at 22°C. The decay constants of AB, calculated by the one-component exponential model, significantly increase with the growth of the incubation temperature: from 0.46 ± 0.01 yr–1 at 2°C to 1.02 ± 0.09 yr–1 at 22°C. Changes in the chemical composition of aspen bark due to the processes of biogenic decomposition include a significant reduction in the amount of alcohol-soluble organic compounds and cellulose to 18–32 and 41–57% of their initial amount, respectively. Lignin losses are less significant, being only 9–18% of their content in AB before the incubation. The quantitative changes in the chemical composition of aspen bark are similar at 2 and 12°C and less pronounced than those at 22°C, which may be explained by an increase in the growing activity of organisms, are actively involved in bark decomposition at 22°C.

Techno-economic analysis of different integrated biorefinery scenarios using lignocellulosic waste streams as source for phenolic alcohols production

The whole process of lignin extraction from a lignocellulosic waste streams (almond shell) by sulfur-free methods and its depolymerization by base catalyzed or solvolysis reactions have been addressed in this work. In addition, the influence of avoiding the lignin isolation stage prior to its depolymerization reaction has been studied based on the final product yields (phenolic monomers compounds, such as catechol derivatives), energy requirements and production costs. As summary, four different scenarios were approached using experimental data values from previous works and compared by the help of a simulation software (AspenTech®). The direct lignin depolymerization from black liquors equalized the phenolic monomer yields of the precipitated lignin depolymerization for the organosolv process (0.08 wt%), and increased in the soda process (0.05 wt% against 0.03 wt%). However, the bigger volume to be treated in the depolymerization reaction and downstream stages significantly increased the production costs (chemicals consumptions, energetic duties and waste stream disposal), as well as the investment cost. Regarding the depolymerization from the precipitated lignin, despite the loss of lignin during the isolation stage, the reduction of the volume to be treated led to hugely reduce the production costs and the environmental impact. Among these last two mentioned scenarios, the organosolv process presented better indicators. Even though the lignin extraction yield was poorer for the organosolv process, the depolymerization performance was improved in such level, that the most desirable product (phenolic oil) was obtained in higher amount.

Decomposition of Organic Chemical Components in Wood by Tropical Xylaria Species.

The ability of Xylaria species obtained from tropical wood and leaf litter to cause a mass loss of lignin and carbohydrates in wood was examined in vitro with pure culture decomposition tests. The mass loss of wood of four tree species caused by nine Xylaria isolates ranged from 4.5% to 28.4% of the original wood mass. These Xylaria isolates have a potential ability to decompose lignin and other recalcitrant compounds, collectively registered as acid unhydrolyzable residues or Klason lignin in wood. The origin of isolates (i.e., isolates from wood versus leaf litter) did not affect the mass loss of acid unhydrolyzable residue in wood. The Xylaria isolates tested generally caused a selective decomposition of polymer carbohydrates in wood in preference to acid unhydrolyzable residue. The mass loss of acid unhydrolyzable residue caused by Xylaria isolates varied with the tree species of the wood and was negatively related to the initial content of acid unhydrolyzable residue in wood, implying the limiting effect of lignin and recalcitrant compounds on wood decomposition by Xylaria isolates.

Cellulose Powder from Piper nigrum L. Agro-Industrial Waste: Effect of Preparation Condition on Chemical Structure and Thermal Degradation

White pepper is generally produced via water retting process to decorticate the pericarp of green pepper. The decorticated pericarp is considered as an agro-industrial waste and environmental pollutant as many farmers still discard the waste into the rivers. These wastes majorly contain cellulose, hemicellulose, pectin, and other organic compound. Cellulose was obtained from alkaline treatment (4 wt. % sodium hydroxides, NaOH) followed by bleaching process. This study reports the effect of soaking cycle in bleaching treatment on the chemical structure and thermal degradation of cellulose. The cellulose obtained from pepper (Piper nigrum L.) pericarp waste were characterised by colour analysis, Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). Increased number of bleaching cycles produced a whiter colour and high thermal stability of cellulose powder. The whiteness index (WI) for high bleaching cycle sample was found significantly high (p<0.05) with the value of 77.00 ± 1.10. Thermal analysis indicates a derivative thermogravimetric analysis (DTG) peak at 332 °C. The FTIR spectrum proven that the condition of bleaching treatment changes the absorption intensity at bands 1732, 1540, and 1460 cm-1 which due to the loss of hemicellulose and lignin. The use of pepper pericarp waste that is usually discarded may provide a sustainable alternative for the production of cellulose.

Lignin from energy plant (Arundo donax): Pyrolysis kinetics, mechanism and pathway evaluation

Pyrolysis of lignin was conducted and main decomposition temperature range was 250–500 °C and the maximum mass loss of lignin occurred at 300–350 °C (10–20 °C/min). Activation energy was ranged from 166 to 182 kJ/mol and lnA was ranged from 35 to 40. All fitting peaks described by mechanism function of random nucleation followed by growth. There was apparent infrared spectroscopy absorbance at 3565, 2950, 2367, 2182, 1775, and 1103 cm−1 because of vibrations of functional group in H2O, CH4, CO2, CO, CO and O-containing compounds. Main composition of bio-oil was phenols and main carbon distribution was ranged from C5 to C8. Ratio of p-hydroxyphenyl, guaiacyl and syringyl structures in bio-oil varied with pyrolysis temperature. Main pyrolysis mechanism of lignin was cracking of typical structure into phenols, cracking of carboxyl groups in side chains to form CO2 and carbonization of aromatic structure to biochar. Lignin showed higher biochar yield (up to 47.46%) and biochar from lignin pyrolysis have high carbon and low ash content. Comparing with direct pyrolysis, fermentation-pyrolysis pathway produced extra high-value products of ethanol (16.70%) and CO2 (8.5%). It indicated a potential and high-value pathway of lignin produced in cellulosic ethanol plants.

Using Wood Rot Phenotypes to Illuminate the "Gray" Among Decomposer Fungi.

Wood-decomposing fungi use distinct strategies to deconstruct wood that can significantly vary carbon release rates and fates. White and brown rot-type fungi attack lignin as a prerequisite to access carbohydrates (white rot) or selectively remove carbohydrates (brown rot). Soft rot fungi use less well-studied mechanisms to deconstruct wood (e.g., cavitation and erosion). These fungi often co-exist in nature, creating a balance in carbon turnover that could presumably “tip” in a changing climate. There is no simple genetic marker, however, to distinguish fungi by rot types, and traditional black and white distinctions (brown and white, in this case) cannot explain a spectrum of “gray” carbon loss possibilities. In this study, we tested 39 wood-degrading fungal strains along this spectrum of rot types. We tracked wood mass loss and chemical changes in aspen blocks in early- to mid-decay stages, including three signatures of fungal nutritional mode measured from wood rather than from fungus: dilute alkali solubility, water-soluble monosaccharides, and lignin loss (%) relative to density loss (%) (L/D). Results were then plotted relative to rot types and correlated with gene counts, combining new data with past results in some cases. Results yielded a novel distinction in soluble monosaccharide patterns for brown rot fungi, and reliable distinctions between white and brown rot fungi, although soft rot fungi were not as clearly distinguished as suggested in past studies. Gene contents (carbohydrate-active enzymes and peroxidases) also clearly distinguished brown and white rot fungi, but did not offer reliable correlation with lignin vs. carbohydrate selectivity. These results support the use of wood residue chemistry to link fungal genes (with known or unknown function) with emergent patterns of decomposition. Wood signatures, particularly L/D, not only confirm the rot type of dominant fungi, but they offer a more nuanced, continuous variable to which we can correlate genomic, transcriptomic, and secretomic evidence rather than limit it to functional categories as distinct “bins.”