Lignin Loss Research Articles

Lignin Loss Mystery in Anaerobic System Resolved

Lignin Loss Mystery in Anaerobic System Resolved Lignin fractions lost (30-70%) during anaerobic digestion of dicot leaf litter has been investigated with potential implications for biomethanation and bioethanol production. Five species of moderately lignified tree leaf species were anaerobically digested and the lignin loss pattern was studied. The pattern of loss showed that syringyl units were the predominant loss from primarily cell wall lignins during the early phase after which lignin of vascular bundles was attacked. FT-IR assays on the Klason lignin indicated even core lignin structures to be altered under prolonged anaerobic degradation and this is being reported for the first time. In all the species studied, lignin degradation was strongly influenced by the leaf area, wax layer and guaiacyl content.

Steam Explosion as a Pretreatment of Cynara cardunculus Prior to Delignification

Cardoon (Cynara cardunculus) stalks were submitted to steam explosion (183 °C, 5 min) with a yield of 88% and a lignin loss of around 7%. Cardoon (C) and steam exploded cardoon (CSE) were characterized by wet chemical analysis and Py-GC/MS. Total lignin and its S/G ratio were 21.6% and 1.35 in C and 22.4% and 1.40 in CSE. These samples were delignified by kraft and organosolv processes. Cardoon pulps were obtained with different yields of 45.1% for kraft and 61.2% for organosolv. Kraft pulps yields were 45.1% and 50.9%, respectively, for Ck and CSE-K, corresponding to a lignin loss of 74.7% and 72.2%. The S/G ratio was similar 1.25 and 1.23. Organosolv pulps presented higher yields (61.2% vs 73.3%) and were less delignified (30.5% vs 13.8%), and the S/G ratio was 1.54 and 1.47, respectively, for Corg and CSE-org. Overall, the condition chosen for steam explosion allowed a low mass loss but did not promote delignification and neither enhanced lignin removal during kraft and organosolv processes.

Effects of post-harvest stigmasterol treatment on quality-related parameters and antioxidant enzymes of green asparagus (Asparagus officinalis L.)

ABSTRACTThe effects of immersion of green asparagus spears in stigmasterol solution (0, 0.5 and 1.0 g l−1, 15 min, 25°C) on weight loss, surface colour, enzyme activities and content of malondialdehyde, total phenol, lignin and chlorophyll were investigated during 40 days of storage at 4 ± 0.5°C. Of the concentrations tested, 0.5 g l−1 treatment was most effective. Stigmasterol (0.5 g l−1) treatment significantly reduced colour changes and losses of fresh weight and chlorophyll content. Superoxide dismutase (SOD) and catalase (CAT) activities were maintained higher in stigmasterol-treated (0.5 g l−1) asparagus, whereas the activity of peroxidase (POD) was significantly reduced. Stigmasterol treatment (0.5 g l−1) also significantly decreased the content of malondialdehyde (MDA) and increased total phenol content. Accumulation of lignin was positively correlated to activity of guaiacol-POD (r = 0.960, p < 0.01) in stigmasterol-treated (0.5 g l−1) asparagus. The polyphenol oxidase (PPO) activity decreased and showed a significant negative correlation with the chroma L* value (r = –0.899, p < 0.01) in stigmasterol-treated (0.5 g l−1) asparagus. It was concluded that stigmasterol treatment (0.5 g l−1) could inhibit the senescence of green asparagus, and therefore prolong its shelf-life, maintaining the quality of post-harvest green asparagus.

Crop residue degradation by fungi isolated from conservation agriculture fields under rice–wheat system of North-West India

In North West-Indo Gangetic Plains (NW-IGP) of India in situ burning of crop residues is practiced by majority of farmers’ which deteriorates soil and environmental quality. Fungi have the potential for lignocellulose degradation and can be used for the in situ decomposition of crop residues. Lignocellulose degrading fungal spp. were isolated and evaluated for the activity of lignocellulolytic enzymes. The lignocellulose degrading fungi were isolated by appearance of zone on carboxy methyl cellulose (CMC) agar media and tannic acid (TA) media. Carboxy methyl cellulase, filter paperase, cellobiase, xylanase and laccase activity were estimated in submerged, as well as solid state fermentation using a mixture of rice and wheat straw in the ratio of 4:1. rice–wheat straw as substrate. The residue left after solid state fermentation was evaluated for carbon/nitrogen ratio, dry mass loss, and loss of cellulose, hemicellulose and lignin. Selected potential isolates were further tested in pot experiment for their effect on wheat plants. The interaction among isolates was also studied. After primary screening, 19 out of a total of 72 fungal isolates were selected based on their enzymatic activity profile and potential to degrade lignocellulosic residues in submerged fermentation. Out of these 19 isolates, 11 were further selected based on their enzymatic secretions in solid state fermentation. All the 11 strains were identified morphologically. Four fungal isolates (RPW 1/3, RPW 1/6, RPWM 2/2 and RZWM 3/2) showed higher enzymatic activities and more loss of dry mass and cell wall constituents over the other isolates. These isolates were identified by ITS region sequencing as Aspergillus flavus, Aspergillus terreus, Penicillium pinophilum and Alternaria alternata. This study revealed that fungal isolates may be used for managing crop residues in conservation agriculture based rice–wheat system of NW-IGP to eliminate ill effects of residue burning.

Dynamics of fungal community composition, decomposition and resulting deadwood properties in logs of Fagus sylvatica, Picea abies and Pinus sylvestris

In forest ecosystems, deadwood is an important component that provides habitat and contributes to nutrient cycles, as well as to carbon and water storage. The change of wood constituents, nutrients and microbial species richness in the field over the whole time of decomposition has only rarely been studied, in particular not in relation to oxidative enzyme activities (mediating lignin degradation) and different forest management regimes.To describe wood decomposition, we selected coarse woody debris (CWD) in form of 197 logs of Fagus sylvatica, Picea abies and Pinus sylvestris in forests with different management regimes across three regions in Germany. They were sampled and analyzed for wood density, water content, wood constituents (Klason and acid-soluble lignin, organic extractives, water-soluble lignin fragments), carbon, nitrogen and metals (Al, Ca, Cu, K, Mg, Mn and Zn). Furthermore, the activities of oxidative enzymes like laccase, manganese peroxidase, and general peroxidase were measured. Since filamentous fungi (Basidiomycota, Ascomycota) are the major biological agents of wood decomposition, fungal species richness based on sporocarps and molecular fingerprints was recorded.Higher forest management intensity had a negative effect on deadwood volume and in consequence on fungal species richness (sporocarps), but hardly to other analyzed variables. Furthermore, there were significant differences between the tree species for the concentrations of wood constituents and most nutrients as well as the activities of oxidative enzymes, although their course during decomposition was mostly similar among the tree species. We found that molecular species richness increased with the period of decomposition in contrast to the number of fruiting species, which was highest in the intermediate stage of decomposition. Both types of species richness increased with increasing volume of the CWD logs. Regarding the entire period of decomposition, white-rot fungi (WRF), based on identification of sporocarps, were the most abundant group of wood-decaying fungi in all three tree species. This corresponds well with the overall presence of laccase and peroxidases and the concomitant substantial loss of lignin, which points to the importance of these enzymes in deadwood decomposition. We found a continuous decomposition and decline of volume-related concentrations in wood constituents and nutrients with time of decomposition. Contrary to volume-related concentrations, the concentrations related to dry mass frequently increased.

Application of copper monoethanolamine solutions as primers for semitransparent exterior wood stains

The effects of copper monoethanolamine (CuA) treatment of wood surfaces on the surface weathering and durability of a semitransparent penetrating stain were compared with those of chromic acid (CrA) treatment which is known as a photoprotective primer, using artificial weathering trials. Chemical changes in chemically treated and untreated wood surfaces during artificial weathering were investigated using Fourier transform infrared (FTIR) spectroscopy. Surface roughness, water contact angle measurements and scanning electron microscopy observations were performed to assess stain durability. Results of FTIR analyses indicated that lignin losses following CuA and CrA treatment were less than those of the untreated wood surfaces during the initial stage of artificial weathering. CuA pretreatment prior to staining also retarded the increase in the average surface roughness compared with that observed for the CrA-pretreated surface and untreated control (only stained) during artificial weathering. Furthermore, CuA pretreatment retarded the decrease in the contact angle compared with that observed for the untreated control, although the use of a highly concentrated CuA solution led to a decrease in the water repellency of the stained wood surface. These results indicated that CuA solution could be used for the pretreatment of wood surfaces to enhance the durability of semitransparent penetrating stains, as long as excessive CuA concentrations are avoided.

亚高山森林林窗大小对凋落叶木质素降解的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 亚高山森林林窗大小对凋落叶木质素降解的影响 DOI: 10.5846/stxb201503240562 作者: 作者单位: 绵阳师范学院,四川农业大学 生态林业研究所/林业生态工程省级重点实验室,四川农业大学 生态林业研究所/林业生态工程省级重点实验室,四川农业大学 生态林业研究所/林业生态工程省级重点实验室,四川农业大学 生态林业研究所/林业生态工程省级重点实验室,四川农业大学 生态林业研究所/林业生态工程省级重点实验室 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（31170423，31270498）；国家“十二五”科技支撑计划（2011BAC09B05）；四川省杰出青年学术与技术带头人培育项目（2012JQ0008，2012JQ0059）；中国博士后科学基金（2012T50782）；四川省教育厅青年基金（2013SZB0553，13ZB0121，13TD0015）；绵阳师范学院校级项目（QD2015A004，2015A01）；生态安全与保护四川省重点实验室开放基金项目（ESP201309，ESP1404） Effects of gap sizes on the lignin degradation of foliar litter in a subalpine forest Author: Affiliation: Ecological Security and Protection Key Laboratory of Sichuan Province,,Long-term Research Station of Alpine Forest Ecosystem, Key Laboratory of Ecological Forestry Engineering, Institute of Ecology & Forestry, Sichuan Agricultural University,Long-term Research Station of Alpine Forest Ecosystem, Key Laboratory of Ecological Forestry Engineering, Institute of Ecology & Forestry, Sichuan Agricultural University,Long-term Research Station of Alpine Forest Ecosystem, Key Laboratory of Ecological Forestry Engineering, Institute of Ecology & Forestry, Sichuan Agricultural University,Long-term Research Station of Alpine Forest Ecosystem, Key Laboratory of Ecological Forestry Engineering, Institute of Ecology & Forestry, Sichuan Agricultural University Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:木质素降解是认识高寒森林凋落物分解过程的关键环节，可能受到林窗大小及其在不同季节水热环境的影响。采用分解袋法，研究了川西亚高山森林不同面积大小林窗下红桦（Betula albo-sinensis）和岷江冷杉（Abies faxoniana）凋落叶在初冻期、深冻期、融化期、生长季节初期、生长季节中期和生长季节后期的木质素分解动态特征。研究结果表明，采样时间和林窗面积大小对两种凋落叶的木质素降解均有显著影响。经历1a分解，红桦凋落叶的木质素降解了21.53%-27.65%，而岷江冷杉凋落叶的木质素富集了7.95%-19.40%。较大林窗促进了冬季岷江冷杉凋落叶和生长季节红桦凋落叶木质素的降解，抑制了冬季红桦凋落叶木质素的降解；而生长季节岷江冷杉凋落叶木质素富集速率则为林下 > 大林窗 > 中林窗 > 小林窗。逐步回归分析表明，凋落叶木质素的降解过程在冬季主要受到负积温和土壤冻融循环次数的影响（木质素结构的物理破碎），而在生长季节则主要受到平均温度和正积温的影响（木质素的生物降解）。可见，川西亚高山森林木质素降解受林窗格局变化的显著影响，且林窗大小对凋落叶木质素降解的影响与物种和分解时期有关。 Abstract:Lignin, a major component of foliar litter, plays a crucial role in litter decomposition process in forest ecosystems. However, forest gap may affect lignin degradation of foliar litter in subalpine forests, since gaps with different sizes not only regulate snow cover and its associated freeze-thaw events in winter, but also affect temperature and moisture conditions during the following growing season; however, little information about the gap size-effect is currently available. To test the seasonal effects of forest gap sizes on litter lignin degradation, a field experiment using litterbags was conducted in a subalpine forest in western Sichuan, which is located along the upper reaches of the Yangtze River and in the eastern part of the Tibetan Plateau. Litterbags containing red birch (Betula albo-sinensis) and Minjiang fir (Abies faxoniana) foliar litter were placed on the forest floor under four gap sizes conditions:a closed canopy, a large gap, an intermediate gap and a small gap. The litterbags were sampled at the onset of the soil freezing, during soil deep freezing and soil thawing, and during the early, middle and late growing season. The experiment was conducted from November 2011 to October 2012. The lignin concentrations of the litter were measured, and the rates of lignin degradation were calculated. The results indicated that season and gap size had significant effects on lignin degradation of both red birch and Minjiang fir litter. Over the course of the one-year study period, lignin losses from the foliar litter were 21.53-27.65% for red birch and-7.95-19.40% for Minjiang fir, across the four size gaps. The large gap promoted the degradation of lignin in the Minjiang fir litter during winter, and that of lignin in the red birch litter during the growing season. Conversely, the large gap inhibited the degradation of lignin in the red birch litter during winter, while the lignin degradation rate of the Minjiang fir litter during the growing season was as follows:closed canopy > large gap > intermediate gap > small gap. In addition, a step-wise regression analysis result revealed that lignin degradation of foliar litter is significantly correlated with negative accumulated temperature and frequency of soil freeze-thaw cycle in winter, suggesting that the degradation of lignin that occurs during winter is mainly driven by physical damage to its molecular structure. Furthermore, close correlations were detected between litter lignin degradation rate and average temperature, and positive accumulated temperature, suggesting that biological processes may contribute to lignin degradation during the growing season. These results imply that differences in forest gap size significantly affect the lignin degradation process of foliar litter in subalpine forests; however, the effects may depend on plant species and season. 参考文献 相似文献 引证文献

Co-Substrating of Peanut Shells with Cornstalks Enhances Biodegradation by Pleurotus ostreatus

World consumption of peanuts has increased tremendously, resulting in abundance of peanut shell waste. The high lignin content of peanut shells limits their bioconversion to useful products or recycling. Therefore, the synergy in co-substrating peanut shells (PS) and cornstalks (CS) to enhance biodegradation was evaluated. Various compositions of peanut shells and cornstalks (% dry weight) herein called co-substrate - 90PS:10CS, 75PS:25CS, 50PS:50CS, 25PS:75CS, 10PS:90CS, and two controls Cont1-100PS and Cont2-100CS were studied under solid state fermentation (SSF) with a white rot fungus, Pleurotus ostreatus for 120 days. A two-factorial experiment in a completely randomized design (CRD) was used. Results showed that substrate composition and fermentation time were important variables in substrate degradation. Lignin degradation, losses in organic matter, cellulose and hemicellulose increased with time. Increasing the composition of CS in co-substrates resulted in higher lignin loss. The most lignin (40.6%) was lost in co-substrates with 75-90% CS whereas more organic matter was lost in co-substrate containing 50% CS and above. Highest losses in organic matter (24.09%), cellulose (17.41%), and hemicellulose (52.07%) occurred in co-substrate with 50% CS, which is where the greatest reduction in C:N ratio (33%) also occurred. The macro- and micro-element content of co-substrates and the controls varied and increased significantly after fermentation. Co-substrating PS and CS appears to be a promising, environmentally-friendly approach for bioconversion of both agricultural wastes into bio-products with potential application in animal feed, biofuel, or for cultivation of mushrooms.

Non-additive effects of water availability and litter quality on decomposition of litter mixtures

Non-additive (synergistic or antagonistic) effect, a common phenomenon for the decomposition of mixed litter in nature, is usually regulated by litter quality and environmental factors. In this study, we investigated decomposition rates and nutrient (C, N, and P) dynamics in response to water availability in six litter treatments using plant material from Dongting Lake, China. Three single-litter treatments (leaves of Carex brevicuspis, leaves of Miscanthus sacchariflorus, and stems of M. sacchariflorus) and three mixed-litter treatments (1:1 mixtures of single litters) were incubated at three levels of water availability (20%, 46%, and 100% saturation) for 120 days in a mesocosm experiment. Decomposition rates for single-litter treatments were ranked: M. sacchariflorus leaves > C. brevicuspis leaves > M. sacchariflorus stems. Decomposition rates generally increased with increasing water availability. Antagonistic or additive interactions occurred in the M. sacchariflorus leaves + M. sacchariflorus stems treatment, and synergistic interactions occurred in the other two mixed-litter treatments. N content and lignin loss rate of M. sacchariflorus leaves and M. sacchariflorus stems were increased by mixing with C. brevicuspis leaves. The magnitude of synergistic interactions increased with increasing water availability and the opposite was true for antagonistic interactions. These data suggest that the direction of non-additive effects is dependent on litter quality, while the magnitude is regulated by water availability.

Lignin Degradation in Foliar Litter of Two Shrub Species from the Gap Center to the Closed Canopy in an Alpine Fir Forest

To understand the effects of forest gaps on lignin degradation during shrub foliar litter decomposition, a field litterbag experiment was conducted in an alpine fir (Abies faxoniana) forest of the eastern Tibet Plateau. Dwarf bamboo (Fargesia nitida) and willow (Salix paraplesia) foliar litterbags were placed on the forest floor from the gap center to the closed canopy. The litterbags were sampled during snow formation, snow coverage, snow melting and the growing season from October 2010 to October 2012. The lignin concentrations and loss in the litter were measured. Over 2 years, lignin loss was lower in the bamboo litter (34.64‐43.89%) than in the willow litter (38.91‐55.10%). In the bamboo litter, lignin loss mainly occurred during the first decomposition year, whereas it occurred during the second decomposition year in the willow litter. Both bamboo and willow litter lignin loss decreased from the gap center to the closed canopy during the first year and over the entire 2-year decomposition period. Compared with the closed canopy, the gap center showed higher lignin loss for both bamboo and willow litter during the two winters, but lower lignin loss during the early growing period. Additionally, the dynamics of microbial biomass carbon during litter decomposition followed the same trend as litter lignin loss during the two winters and growing period. These results indicated that alpine forest gaps had significant effects on shrub litter lignin loss and that reduced snow cover during winter warming would inhibit shrub lignin degradation in this alpine forest.

Wood facade materials ageing analysis by FTIR spectroscopy

Attenuated total reflection Fourier transform infrared spectroscopy is used in this study to quantify wood degradation. Nine different types of wood materials were studied. All types of wood were exposed in an Atlas solar simulator against artificial climate conditions. Additionally, natural climate exposure was performed for all types of wood at an outdoor test site in Trondheim, Norway, for 4 years. Surface treatment enhanced the durability of the wood and their performance against weathering. Rough surfaces might reduce the resistance against degradation in comparison with planed surfaces. The degradation during climate exposure created loss of lignin and accumulation of cellulose at the surface.

Using 2D NMR spectroscopy to assess effects of UV radiation on cell wall chemistry during litter decomposition

Litter chemistry is one of the most studied controls on decomposition in terrestrial ecosystems. Solar radiation has been shown to increase litter decomposition rates in arid ecosystems through the process of photodegradation. However, it remains unclear how photodegradation affects litter chemistry, especially the abundance and composition of lignin, which is thought to play a key role in photodegradation. Using two-dimensional nuclear magnetic resonance (2D NMR) spectroscopic methods, we quantified the molecular-level changes in litter chemistry associated with photodegradation. Litter of Bromus diandrus was exposed in the field to two levels of radiation [with and without ultraviolet (UV) wavelengths] and two durations of exposure (2.5 months during summer, and 1 year). Through fiber analysis by sequential digestion, we found that the litter hemicellulose fraction decreased significantly from 31.6 to 24.9 % after 1 year of decomposition. In litter exposed for 1 year, the hemicellulose fraction was significantly lower in litter with UV exposure compared to litter without UV exposure (23.8 vs. 25.9 %). These results indicate that UV photodegradation has a small but significant effect on litter chemistry compared to other decomposition processes. Even though fiber analysis showed no loss of total lignin, 2D NMR analysis demonstrated that UV exposure reduced the major lignin structural units containing β-aryl ether inter-unit linkages by 9 % and decreased the relative abundance of lignin p-hydroxyphenyl units by 20 %. The 2D NMR analysis also revealed that lignin guaiacyl units were preferentially lost after 1 year of decomposition relative to the reference material, but no effects of UV exposure on guaiacyl units were observed. These results suggest that photodegradation causes partial degradation, not necessarily complete breakdown, of lignin structures. Our data also demonstrate that applications of 2D NMR methods are valuable for acquiring detailed information on lignin and polysaccharide chemistry during both biotic and abiotic decomposition processes.

Climate change may reduce litter decomposition while enhancing the contribution of photodegradation in dry perennial Mediterranean grasslands

Understanding how the interactions between solar UV radiation and climate will affect leaf litter decomposition is fundamental to predict how soil and ecosystem biogeochemical cycles will respond to ongoing climate change. We carried out a manipulative experiment to investigate how UV radiation and its interaction with increased temperature (3 °C on average) and a ∼35% reduction in precipitation affect the decomposition of “standing” and “on the ground” litter of Stipa tenacissima, a dominant species in semiarid Mediterranean grasslands. UV radiation was manipulated using specially designed screens that either passed or blocked 90% of the UV radiation. All climate change manipulation treatments decreased litter decomposition compared to the control treatment. In particular, litter decay rates were reduced by a 34%, 43% and 62% in the rainfall reduction (RE), warming (W), and the combination of warming and rainfall reduction (WRE) treatments, respectively, compared to the control treatment. Across climate manipulation treatments, higher decay rates were observed in litter exposed to UV radiation than in litter non-exposed to UV radiation, and in litter placed on the ground than in standing litter. However, significant interactions were found between climate manipulation and UV exposure or position treatments. In the control and RE treatments, litter on the ground decomposed 25% faster than standing litter. In the W and WRE treatments, litter decomposition rates increased by 29% when exposed to UV radiation despite lower overall decay rates were observed in these treatments. Overall, lignin losses were parallelled by increases in soluble cell materials, particularly when litter was exposed to UV radiation. Our results indicate that predicted climate change scenarios will likely reduce leaf litter decomposition rates, while enhancing the relative contribution of photodegradation to overall litter decomposition in dry perennial Mediterranean grasslands.

Initial white rot type dominance of wood decomposition and its functional consequences in a regenerating tropical dry forest

Efforts to model woody debris dynamics are limited by our empirical understanding of the patterns and drivers of decomposition. This knowledge gap is significant in tropical forests, particularly in the dry tropics where research has been minimal and where forest regeneration is a management priority. Here, we coupled trait-function relationships in decomposing logs with indices of microbial and insect activity in a regenerating Costa Rican dry forest. We cut and placed logs (∼18 cm dia) of eight tree species in ground contact at two sites. We assessed density loss and element dynamics in sapwood and heartwood twice annually over two years. At time 0 and year 2, we measured lignin, nitrogen, structural carbohydrates, extractives, insect galleries, and two residue ‘signatures’ of fungal rot type: dilute alkali solubility (DAS; higher for brown rot) and lignin:glucan loss (higher for white rot). After two years, sapwood mean density losses ranged from 11.6 to 44.4% among tree species (excluding one thoroughly-degraded species). The best predictor of sapwood density loss was initial pH, but this correlation was negative, contrasting positive correlations proposed for temperate forests. Mean heartwood density losses were consistently less than those in sapwood, and although heartwood extractives contents were as high as 16.4%, trait correlations were insignificant. Insect galleries contributed little to density loss (<3%), and DAS and lignin loss patterns indicated dominance by white rot fungi. This was often matched by dense fungal zone line patterns (spalting), outlining many small territories. Perhaps as a consequence, element patterns were spatially variable, with overall trends roughly similar to those from temperate studies (e.g., Ca gain, P, K loss). Estimated CO2 fluxes from logs ranged from ∼25 to 75% percent of annual fluxes from litter fall. This collectively implies an important role for wood decomposition in dry forest carbon cycling, and in our case, it shows an interesting pattern suggesting high decomposer spatial complexity but low functional diversity.

Water uptake, chemical characterization, and tensile behavior of modified banana–plantain fiber and their polyester composites

Banana–plantain fibers (BPFs) were treated with acetic anhydride (AA), epichlorohydrin (EP), and an acetic anhydride–epichlorohydrin blend (AA_EP). Natural fiber–polyester composites (PCs) were fabricated using untreated and treated BPF by the hand lay‐up technique. Modified BPF Raman and Infrared spectroscopy (ATR‐FTIR) analysis revealed losses of lignin and hemicelluloses and new chemical bonds that confirmed the replacement of part of the raw fiber hydroxyl groups, which gave rise to a degree of hydrophobicity in the treated fibers. This change altered their water sorption isotherms, swelling behavior in water, impedance spectroscopy, and XRD analysis. Assays of water absorption and tensile resistance for untreated BPF (U) and modified BPF polyester composites demonstrated a remarkable reduction in water intake, whereas tensile strength was maintained (P &lt; 0.05) for the modified BPF polyester composites. POLYM. COMPOS., 37:2960–2973, 2016. © 2015 Society of Plastics Engineers

Kinetic Study of Catalytic Steam Gasification of Biomass by Using Reactive Flash Volatilisation

AbstractReactive flash volatilisation is an autothermal process to convert biomass into tar‐free synthesis gas under steam‐rich conditions. This article studies the kinetics of reactive flash volatilisation by using Ni, PtNi, RuNi, ReNi, and RhNi catalysts supported on alumina. The rates of mass loss of cellulose, xylan, and lignin were measured and compared with those of the synthetic biomass mixture and pinewood sawdust. The kinetic parameters were calculated with and without catalysts by using a wire‐mesh isothermal thermogravimetric analyser in an equimolar steam/N2 atmosphere and high heating rates of 8.6×102, 1.1×103, and 1.3×104 °C min−1 at 700, 750, and 800 °C, respectively. The results revealed three distinct regimes of the rate of mass loss: pyrolytic decomposition, reforming, and char gasification. The catalysts increased the rate of mass loss in the reforming regime. RhNi and RuNi supported catalysts showed higher reforming rates than other catalysts. This study provides direct evidence of the in situ catalytic removal of tar during gasification of biomass.

Comparison of acetyl bromide lignin with acid detergent lignin and Klason lignin and correlation with in vitro forage degradability

The spectroscopic acetyl bromide lignin (ABL) and two versions of the gravimetric sulfuric acid lignin method [Lignin (sa)] were compared for their correlations with in vitro forage dry matter (IVDMD) and neutral detergent fiber degradability (IVNDFD) assays of 73 grass and legume samples. The two versions of Lignin (sa) were the acid detergent lignin (ADL) and Klason lignin (KL) methods. ABL and KL methods employ crude cell wall as the fibrous preparation while ADL uses acid detergent fiber. In vitro forage measures of degradability were negatively correlated with almost all lignin values, but the ABL method had the highest correlation coefficients for both grasses and legumes. Regression curves of ADL values with grass and legume IVDMD and IVNDF revealed different slopes, with steeper curves for grasses. With KL, grass and legume IVDMD and IVNDFD slopes were statistically similar and parallel. The results observed in the ADL and KL methods testify to the distance between the lines and data points, that is, these methods are poor predictors of NDF degradability. Grass and legume samples assayed with the ABL procedure, exhibited similar slopes, with parallel lines for both IVDMD and IVNDFD assays. Steeper inclination of curve for grasses relative to legumes in the ADL method may be attributed to partial loss of lignin during the procedure. This shows that ABL can accurately and consistently measure the inhibitory effect of lignin on degradation of structural carbohydrates of both grasses and legumes. The ABL method provides an accurate, easy and fast procedure for quantifying lignin in plant materials. A step-by-step laboratory procedure of the ABL method is described.

Mechanical properties and chemical composition of beech wood exposed for 30 and 120 days to white-rot fungi

Abstract The effects of exposing specimens of Oriental beech [Fagus sylvatica subsp. orientalis (Lipsky) Greuter and Burdet] to the white-rot fungi Pleurotus ostreatus (Jacq.: Fr.) Kummer and Trametes versicolor (L.: Fr.) Pilát strain 325 have been studied concerning the mechanical properties and chemical composition in terms of carbohydrates, cellulose, and lignin. Biological decay tests were carried out in accordance with the EN 113 standard specifications for 30 and 120 days. P. ostreatus had nearly the same deteriorating effects on the mechanical properties and chemical composition as that caused by T. versicolor. High and significant correlations were found between some mechanical properties with chemical components; for instance, the correlation coefficient (R2) between impact bending and carbohydrate content was about 0.96. The changes of components influence the various mechanical properties to a different degree. Incipient fungal decay caused severe changes for impact bending and carbohydrate loss. Several other properties declined at 120-day exposure time, such as the hardness, compression strength parallel to grain, and cellulose and lignin losses.

Fungus-assisted mild acid pretreatment of Glycyrrhiza uralensis residues to enhance enzymatic hydrolysis and oil production by green microalga Chlorella protothecoides

The potential of fungal pretreatment prior to acetic acid pretreatment using Phanerochaete chrysosporium for enzymatic hydrolysis and algal oil production from Glycyrrhiza uralensis residue (GUR) was investigated. After co-pretreatment with P. chrysosporium and acetic acid, the loss of lignin and holocellulose was 47.4% and less than 28%, respectively. Subsequently, the acid insoluble residues were further hydrolyzed with cellulase into fermentable sugars, and then used for heterotrophic cultivation of Chlorella protothecoides for bio-oils production. The concentration of reducing sugars in enzymatic hydrolyzate from co-treated GUR was 1.62 times as that of solely acid pretreated GUR. The maximum yield of algal biomass and oil from co-pretreatment (4.46 and 1.91g/L) were both higher than those from sole acid pretreatment. Thus, this study demonstrated the feasibility of using reducing sugars obtained from enzymatic hydrolysis of GUR co-treated with P. chrysosporium and acetic acid as substrate for oil production.

Metabolite secretion, Fe3+-reducing activity and wood degradation by the white-rot fungus Trametes versicolor ATCC 20869

Trametes versicolor is a promising white-rot fungus for the biological pretreatment of lignocellulosic biomass. In the present work, T. versicolor ATCC 20869 was grown on Pinus taeda wood chips under solid-state fermentation conditions to examine the wood-degrading mechanisms employed by this fungus. Samples that were subjected to fungal pretreatment for one-, two- and four-week periods were investigated. The average mass loss ranged from 5 % to 8 % (m m−1). The polysaccharides were preferentially degraded: hemicellulose and glucan losses reached 13.4 % and 6.9 % (m m−1) after four weeks of cultivation, respectively. Crude enzyme extracts were obtained and assayed using specific substrates and their enzymatic activities were measured. Xylanases were the predominant enzymes, while cellobiohydrolase activities were marginally detected. Endoglucanase activity, β-glucosidase activity, and wood glucan losses increased up to the second week of biodegradation and remained constant after that time. Although no lignin-degrading enzyme activity was detected, the lignin loss reached 7.5 % (m m−1). Soluble oxalic acid was detected in trace quantities. After the first week of biodegradation, the Fe3+-reducing activity steadily increased with time, but the activity levels were always lower than those observed in the undecayed wood. The progressive wood polymer degradation appeared related to the secretion of hydrolytic enzymes, as well as to Fe3+-reducing activity, which was restored in the cultures after the first week of biodegradation.