Lignin Loss Research Articles

Characterization of manganese(II)-coupled functional microorganisms in driving lignin degradation during straw composting

The intricate structure of lignin in straw makes it challenging to hydrolyze, making it a key focus of current research. However, there has been limited study on the effect of enzyme inducer (MnSO4) combined with functional microorganisms on lignin degradation during straw composting. Based on this, four composting treatment groups were set up in this study. Control (CK), functional microorganism addition treatment (F), Mn2+ enzyme inducer (Mn), and Mn2+ enzyme inducer coupled with functional microorganism addition treatment (FMn) were tested for composting. Manganese(II)-coupled microorganisms improved lignin degradation: FMn > Mn > F > CK. They increased the lignin loss rate from 25.54 % to 42.61 %. Laccase activity increased from 3.45 to 43.74 U/g and manganese peroxidase activity increased from 145.52 to 264.91 U/g. And gene abundance was increased. Microbial community structure and dominant genera changed. Structural equations support the idea that functional microorganisms coupled with manganese can modify physicochemical indices, thereby regulating gene expression and enhancing enzyme activity. Furthermore, the stimulation of fungal growth and increased extracellular laccase and manganese peroxidase activities can affect the degradation of lignin. This study provides new insights and theoretical support for efficient lignin degradation and efficient resource utilization of compost products.

Biorefinery electrification of brewers’ spent grains using plasma bubbles for sustainable production of poly(3-hydroxybutyrate)

Biorefinery electrification could be implemented for sustainable refining of crude renewable resources eliminating the use of high temperatures and pressures, alkaline and acidic solutions and conventional solvents. A plasma bubble reactor using air as the feed gas was employed to enhance poly(3-hydroxybutyrate) (PHB) production from brewers’ spent grains (BSG) facilitating the fractionation of protein and lignin as value-added co-products. Plasma factors (voltage, pretreatment duration, duty cycle, initial solids concentration) were evaluated with the highest overall conversion yield of glucan and hemicellulose (73 %, 0.494 g sugars/gBSG) achieved for initial solids concentration of 150 g/L. The produced BSG hydrolysate led to higher PHB production efficiency (130 g/L total dry weight, 74.4 gPHB/L, 0.32 g/g yield, 2.64 g/L/h productivity) than conventional hydrolysates produced by enzymatic hydrolysis alone and enzymatic hydrolysis combined with hydrothermal treatment. The protein and lignin losses in the remaining BSG solids were 24.1 % and 29.2 % respectively. When renewable electricity is employed, the global warming potential was estimated at 0.59 kg CO2-eq per kgPHB and the abiotic depletion potential fossil at 11.12 MJ per kgPHB for PHB production based on plasma treated BSG. In the proposed biorefinery concept, 1 kg BSG could be converted into 147.6 g PHB with a solid fraction containing 137.4 g protein and 98.4 g lignin that could be subsequently fractionated as value-added co-products. The rationale of this study is to demonstrate that BSG plasma treatment can be used for the exploitation of the full potential of BSG for the production of PHB with improved environmental impact and minimal losses of protein and lignin.

Carbon fixation mechanism of fungal community bypass strategy in rice straw composting combined with functional microbes: inhibition from cellobiose to glucose pathway

Composting offers an eco-friendly approach, converting organic solid waste into valuable soil enhancer products. Three experimental treatments were designed to explore the microbial mechanisms influencing lignocellulose loss in rice straw composting: CK (the control), B4 (inoculated with Bacillus subtilis), and Z1 (inoculated with Aspergillus fumigatus). The results showed significant increases in carboxymethyl cellulase, cellobiohydrolase, laccase, and xylanase activities during B4 and Z1composting. However, lignin peroxidase and manganese peroxidase were not significantly affected, and β-glucosidase was inhibited. Additionally, microbial inoculation stimulated lignin loss, with B4 and Z1 composting increasing degradation by 14.42% and 16.29%, respectively, compared to the CK. Simultaneously, humic substance content increased as microbial inoculation inhibited β-glucosidase, causing cellobiose to accumulate and divert into a pathway that forms humic substances. The random forest model showed that Symmetrospora and Phaeosphaeria significantly boosted lignocellulose loss in B4 and Z1 composting by promoting fungi functional aggregation, thus accelerating the degradation and transformation process. This study explored the microbial mechanism of lignocellulose loss and provided new insights into lignocellulose conversion and carbon fixation.

EFFECT OF HYDROGEN-PEROXIDE TREATMENT ON THE PHYSICO-MECHANICAL PROPERTIES OF FLAX FIBERS

<p><span lang="SR-LATN-RS">Flax fibers contain cellulose and different impurities (hemicelluloses, lignin, pectin, waxes and fats, mineral salts, natural coloring matter and water soluble compounds). From the ecological and industrial aspect, hydrogen peroxide is the most acceptable component for modification of flax fibers. The aim of the modification of flax fibers is to remove non-cellulose components and improve the fiber quality without significant changing of the mechanical properties. Flax fibers were treated with hydrogen peroxide solutions at concentrations 1%, 2% and 4% at 50 °C, 80 °C and boiling temperature for time period of 60 min. With the removal of non-cellulosic substances from fibers, it has been achieved a high degree of fiber separation and a significant increase of modified fibers fineness. The value for fineness of modified fibers was reduced about 2-4-fold and the modified flax fibers were softer to the hand, unlike unmodified fibers that are very coarse and stiff. However, the weight loss and removal of lignin, which gives the fibers strength, as well as a partial damage of the cellulose itself during the severity of treatment, brought to reduction in the tensile strength of the modified fibers. </span></p>

Novel techniques for the mass production of nutritionally improved, fungus-treated lignocellulosic biomass for ruminant nutrition.

Laboratory-scale experiments have shown that treatment with selective lignin-degrading white-rot fungi improves the nutritional value and ruminal degradability of lignocellulosic biomass (LCB). However, the lack of effective field-applicable pasteurization methods has long been recognized as a major obstacle for scaling up the technique for fungal treatment of large quantities of LCB for animal feeding. In this study, wheat straw (an LCB substrate) was subjected to four field-applicable pasteurization methods - hot-water, formaldehyde fumigation, steam, and hydrated lime - and cultured with Pleurotus ostreatus grain spawn for 10, 20, and 30 days under solid-state fermentation. Samples of untreated, pasteurized but non-inoculated and fungus-treated straws were analyzed for chemical composition, aflatoxin B1 (AFB1 ), and in vitro dry matter digestibility (IVDMD), in vitro total gas (IVGP), methane (CH4 ), and volatile fatty acid (VFA) production. During the 30-day fungal treatment, steam and lime pasteurized straws had the greatest loss of lignin, resulting in marked improvements in crude protein (CP), IVDMD, IVGP, and total VFAs. Irrespective of the pasteurization method, the increase in IVDMD during fungal treatment was linearly (R2 = 0.77-0.92) related to lignin-loss in the substrate during fungal treatment. The CH4 production of the fungus-treated straw was not affected by the pasteurization methods. Aflatoxin B1 was within the safe level (<5 μg kg-1 ) in all pasteurized, fungus treated straws. Steam and lime were promising field-applicable pasteurization techniques to produce nutritionally improved fungus-treated wheat straw to feed ruminants. Lime pasteurization was more economical and did not require expensive energy inputs. © 2023 Society of Chemical Industry.

Functional conservation and preservation of waterlogged archaeological wood

Waterlogged archaeological wood of shipwrecks has been preserved under seawater for centuries, such that microbial erosion has caused severe bacterial degradation and acidification. These wooden cultural relics are of great significance for understanding the shipbuilding technology, trade activities, and environmental ecology of centuries ago. From the perspective of structure and composition, these waterlogged archeological woods have the characteristics of high water content and a large loss of lignin and cellulose, which makes the hull prone to collapse during preservation. Therefore, it is urgent to apply conservation and preservation treatments for deacidification and consolidation. Due to the fragility of wood and the complexity of repair work, the current development of conservation and preservation technology has multiple aims, such as antibacterial, deacidification, and reinforcement effects. In this editorial, the current challenges and conservation treatments with antimicrobial or deacidification utilities will be introduced.

Establishment of patterns in the thermal modification of dry pine wood

One of the methods of ensuring the durability of dry wood during operation is its thermal modification, which inhibits the life processes of the fungus of the Ceratostomaceae family and leads to a change in its structure and properties. Therefore, the object of research was thermally modified dry pine wood affected by a fungus of the Ceratostomaceae family. Physicochemical studies of changes in the structure of thermally modified dry pine wood showed that the samples have absorption spectra that are characterized by fluctuations of the glucopyranose ring of cellulose and are an indicator of the beginning of destructive processes. At the same time, the data of thermogravimetric analysis show the processes of water loss and decomposition of hemicellulose, cellulose, and lignin, and burning of coke residue. Bending and compressive strength of thermally modified dry pine wood shows that as the wood dries, the strength limit decreases depending on the degree of fungus damage. Namely, with an area of biological damage within 10 %, the strength limit is reduced by more than 1.2 times when modified at 200 °С/3 hours, by more than 1.9 times at 200 °С/6 hours. With an increase in the degree of fungal damage to 30÷50 %, the strength limit decreases by more than 1.6 times when modified at 200 °С/3 hours, by more than 2.1 at 200 °С/6 hours. And when affected by a fungus in the range of 80÷100 %, the wood becomes softer, more plastic, while the bending strength is reduced by 1.7 times, and the compressive strength by 1.16 times. Thermal modification of dry pine wood at 200 °С for 3 hours reduces the level of water absorption by more than 1.5 times, and for 6 hours ‒ by more than 1.7 times. The practical importance is that the results of determining changes in the structure and properties of thermally modified dry pine wood make it possible to establish the scope and conditions of its application

Warmer temperature promotes the contribution of invertebrate fauna to litter components release in an alpine meadow on the Qinghai-Tibetan Plateau

How warming and invertebrate fauna concurrently influence litter carbon and nutrient turnover in alpine meadow is still poorly known. Using a litterbag technique, we evaluated the effects of temperature (ambient temperature vs. warming temperature) × mesh (fine mesh without invertebrate fauna access vs. coarse mesh with invertebrate fauna access) on litter decay (i.e., carbon and nitrogen release, lignin and cellulose degradation) across two typical seasons (cold season vs. warm season) in an alpine meadow ecosystem on the Qinghai-Tibetan Plateau. Our results showed that the whole-soil-profile warming significantly increased litter cellulose degradation (+47%), but less affected the decay of other litter components (i.e., carbon, nitrogen, and lignin: + 7–18% increase). The loss of nitrogen and lignin from litter significantly increased by ca. 2 times in the presence of invertebrate fauna. Moreover, the release of all litter chemical components was significantly faster (by 1.5–5.2 times) in warm season than in cold season. Further, litter carbon release and lignin degradation rates were markedly influenced by the interacting effects of mesh × season, and mesh × temperature, respectively. Overall, these findings highlight the importance of invertebrate fauna as a commonly overlooked co-determinant of the warming effect on litter decay patterns in cold biomes; the changed release rates of litter components in the context of on-going warming may have far-reaching effects on carbon and nutrient cycling in alpine ecosystems.

Improving Fiber-Matrix Compatibility by Surface Modification of Coconut Coir Fiber Using White Rot Fungi

Compatibility between elements in natural fiber based-composite always becomes a hot issue. The presence of lignin in natural fibers inhibits interlock with its matrix. This research investigates the degradation of lignin encapsulating coconut coir fiber using white-rot fungus (Pleurotus Ostreatus) and its effect on composite compatibility. The process of delignification was carried out by exposing coconut coir fibers in the media where the white-rot fungus was incubated and grown. The period of exposure was 10, 20, and 30 days, and the ratio of coconut coir fiber to white-rot fungi were 1:1, 1:1.5, and 1.5:1 (by weight). To find the effect of delignification, several tests were conducted namely lignin content, fiber surface morphology, wettability, and pull-out tensile test. The results show that there is a reduction in the lignin content of the fibers. The largest reduction is 27.11% for 30 days of exposure times with the ratio of 1:1.5. The surface morphology of the fibers is smoother due to the loss of lignin. In the wettability test, it is found a decrease in the contact angle between the fibers and the resin. In line with that, the pull-out tensile test reveals a double increase in the IFSS value reaching 115.54%. This significant improvement might be due to the interlocking ability contributed by surface modification of the fibers. Since this chemical-free treatment promotes good composite compatibility, it might be introduced as an environmentally friendly treatment in the production of natural fiber based-composites

Preparation and Characterization of the Composition of Volatile Compounds, Fatty Acids and Thermal Behavior of Paprika.

This study aimed to investigate the thermal behavior and composition of volatile compounds, fatty acids and polyphenols in paprika obtained from peppers of different countries. The thermal analysis revealed various transformations in the paprika composition, namely drying, water loss and decomposition of volatile compounds, fatty acids, amino acids, cellulose, hemicellulose and lignin. The main fatty acids found in all paprika oils were linoleic (20.3-64.8%), palmitic (10.6-16.0%) and oleic acid (10.4-18.1%). A notable amount of omega-3 was found in spicy paprika powder varieties. The volatile compounds were classified into six odor classes (citrus (29%), woody (28%), green (18%), fruity (11%), gasoline (10%) and floral (4%)). The total polyphenol content ranged between 5.11 and 10.9 g GA/kg.

Identification, characteristics and rice growth promotion of a highly efficient cellulolytic bacterial strain, Cellulomonas iranensis ZJW-6, isolated from paddy soil in central China.

The microbial degradation of lignocellulose is the best way to treat straw, which has a broad application prospect. It is consistent with the idea of agricultural sustainable development and has an important impact on the utilization of biomass resources. To explore and utilize the microbial resources of lignocellulose degradation, 27 lignocellulose degrading strains were screened from 13 regions in China. ZJW-6 was selected because of its 49.6% lignocellulose weight loss rate. According to the theoretical analysis of the experimental results, the following straw degradation conditions were obtained by ZJW-6: nitrogen source input of 8.45 g/L, a pH of 8.57, and a temperature of 31.63°C, the maximum weight loss rate of rice straw could reach 54.8%. It was concluded that ZJW-6 belonged to Cellulomonas iranensis according to 16S rRNA-encoding gene sequence comparison and identification. ZJW-6 is a Gram-positive bacterium that grows slowly and has a small yellowish green colony. To explain the degradation mechanism of lignocellulose, the experiment of enzymatic properties of the strain was prepared and carried out. It was discovered that ZJW-6 has an excellent ability to degrade cellulose, hemicellulose, and lignin, with cellulose and hemicellulose loss rates reaching almost 50% in 4 days and lignin loss rates reaching nearly 30%. Furthermore, ZJW-6 demonstrated lignocellulose degradation under aerobic and anaerobic conditions, indicating the strain's broad application potential. ZJW-6 was found to be more effective than ordinary humic acid in improving rice soil (available phosphorus, available nitrogen, organic matter) and promoting rice growth in a rice pot experiment (increasing root-shoot ratio, root activity, chlorophyll content and net photosynthetic rate). ZJW-6 plays an important role in promoting the development and utilization of straw resources. It has important significance for the advancement of green agriculture.

Species evenness affects algae driven co-metabolism with aquatic plant residues

Understanding the mixed decomposition processes of aquatic plant residues is crucial for evaluating the carbon cycle of lakes. However, the complex effect of species evenness, and especially the algae driving co-metabolism effect in eutrophic lakes are still far from clear. In this study, three dominant aquatic plants (Phragmites australis, Nymphoides peltatum, and Potamogeton malaianus) and algae from the typical eutrophic and shallow Lake Taihu, China, were selected to simulate their mixed decomposition process. The addition of algae accelerated the mass loss of cellulose, hemicellulose, and lignin of aquatic plant residues and increased the total mass loss by 2.29~6.32% in mixed decomposition. The positive co-metabolism effect, with the intensity ranging from 10% to 17%, occurred during the mixed decomposition process. In addition, the positive co-metabolism effect was also found among plant residues during mixed decomposition and the co-metabolism intensity of species evenness mixed decomposition was more than twice as high as that of non-evenness mixed decomposition. The addition of algae during the decomposition of aquatic plant residues altered the stoichiometry of available nutrients and affected the microbial decomposition activity. The abundance of decomposition bacteria, especially Bacteroidetes, was increased and the community structure also changed, as evidenced by a 71% increase in the number of bacteria phylum. As a result, these biogeochemistry processes accelerated the decomposition rates of aquatic plant residues and thus produced the positive co-metabolism effect. Therefore, the co-metabolism effects of mixed decomposition described in this study are prevalent in eutrophication lakes and have important effects on the lake carbon cycle, which need to be considered in future lake management.Graphical

Nutrient controls on carbohydrate and lignin decomposition in beech litter

Nutrient pollution has increased plant litter nutrient concentrations in many ecosystems, which may profoundly impact litter decomposition and change the chemical composition of litter inputs to soils. Here, we report on a mesocosm experiment to study how variations in the nitrogen (N) and phosphorus (P) concentrations in Fagus sylvatica (European beech) litter from four sites differing in bedrock, atmospheric deposition, and climate affect lignin and carbohydrate loss rates and residual litter chemistry. We show with pyrolysis GC/MS and elemental analysis that nutrient concentrations had a strong influence on changes in litter chemistry during early decomposition (0–181 days), when greater lignin loss rates were associated with low P concentrations, whereas carbohydrate and bulk C loss were associated with high N concentrations. Nutrient concentrations, in contrast, did not influence changes in litter chemistry in the later decomposition stage (181–475 days), where the decomposition rates of lignin, carbohydrates, and bulk C all increased with litter N concentration and no differences in decomposition rates between major compound classes were detected. Our data indicate that these differences were related to the transition from increasing to constant or declining microbial biomass, and an associated decrease in microbial dependence on the mobilization of nutrients from the insoluble litter fraction.

UV radiation doubles microbial degradation of standing litter in a subtropical forest

Abstract UV radiation has been recognized as a direct driver of litter decomposition by photodegrading organic matter in dryland ecosystems. However, the importance and mechanism of UV radiation on litter decomposition, especially on standing litter, in humid forest ecosystems remain unclear. We conducted a factorial experiment in a humid subtropical forest gap, manipulating the effects of UV radiation on the decomposition of standing litter under different microbial conditions. After 366 days of standing incubation, under normal conditions (UV pass with microorganisms), up to 40.63% of the litter mass was lost. However, under a UV pass without microorganisms, litter mass loss was only 16.30%. Under a UV block, the mass loss of litter with microorganisms was 27.68% and that of litter without microorganisms was 15.54%. Without microorganisms, UV radiation had no significant effect on the mass loss of litter carbon. However, UV radiation increased the DOC concentration of litter. And in the presence of microorganisms, UV radiation contributed to an increased mass loss of lignin by 16.72% and of cellulose by 14.75%. No negative effects of UV radiation on microorganisms were observed. These results suggest that UV radiation increased the net mass loss of litter by 106.67%, and this doubling promotion was achieved through microbial degradation. Synthesis. The increase in microbial degradation under UV radiation may be linked to the increased degradability of lignin and cellulose caused by photodegradation. Our study indicates that direct photodegradation by UV radiation could be weak in subtropical forests, but UV photofacilitation generates rapid turnover of carbon in this system.

Biochemical Changes During Solid State Fermentation of Wheat Crop Residues by Aspergillus flavus Link and Aspergillus niger van Tieghem

In the present investigation authors assessed the biochemical modifications during solid-state fermentation of various ingredients of post harvested wheat crop leftovers by the application of Aspergillus flavus Link and Aspergillus niger van Tieghem. The post harvested wheat crop residues samples, including internodes, leaves, chaff, and straw, were assembled from a natural field and subjected to different decomposition stages for 40 and 60 days. The collected samples were allowed for biochemical modifications and results compared with undecomposed initial samples. The fungi A. flavus caused maximum decomposition of leaves, followed by straw chaff and internodes. The contribution of different fractions to the loss is fat and waxes, followed by simple sugars, amino acids, peptides, minerals, etc., during the first 40 days. In the next 20 days, the decomposition rate increased in wheat leaves, chaff, and straw with peak decomposition or loss of hemicellulose, cellulose, lignin, and pectin. The fungi A. niger caused a primary loss in weight of leaves during the first 40 days and followed mixed straw, chaff, and internodes during in vitro investigation. The loss in dry weight of internodes at successful experimentation and treatment of 40 days for the decomposition was recorded significantly because of the hemicellulose and cellulose components decomposition. However, pectin decomposition contributed to a reasonable extent to the loss of dry weight than other trace fractions. The components like leaves, chaff, and straw showed the same trends in biochemical changes as well. The partial decomposition of lignin was recorded during this period of investigation. The significance of useful facts was uncovered by performing suitable descriptive and inferential statistics. This study has a socio-economic relevance to managing the agricultural residues as a valuable natural resource for green and sustainable Agri-Farming.

The amounts and ratio of nitrogen and phosphorus addition drive the rate of litter decomposition in a subtropical forest

Nitrogen (N) and phosphorus (P) control biogeochemical cycling in terrestrial ecosystems. However, N and P addition effects on litter decomposition, especially biological pathways in subtropical forests, remain unclear. Here, a two-year field litterbag experiment was employed in a subtropical forest in southwestern China to examine N and P addition effects on litter biological decomposition with nine treatments: low and high N- and P-only addition (LN, HN, LP, and HP), NP coaddition (LNLP, LNHP, HNLP, and HNHP), and a control (CK). The results showed that the decomposition coefficient (k) was higher in NP coaddition treatments (P < 0.05), and lower in N- and P-only addition treatments than in CK (P < 0.05). The highest k was observed with LNLP (P < 0.05). The N- and P-only addition treatments decreased the losses of litter mass, lignin, cellulose, and condensed tannins, litter microbial biomass carbon (MBC), litter cellulase, and soil pH (P < 0.05). The NP coaddition treatments increased the losses of litter mass, lignin, and cellulose, MBC concentration, litter invertase, urease, cellulase, and catalase activities, soil arthropod diversity (S) in litterbags, and soil pH (P < 0.05). Litter acid phosphatase activity and N:P ratio were lower in N-only addition treatments but higher in P-only addition and NP coaddition treatments than in CK (P < 0.05). Structural equation model showed that litter MBC, S, cellulase, acid phosphatase, and polyphenol oxidase contributed to the loss of litter mass (P < 0.05). The litter N:P ratio was negatively logarithmically correlated with mass loss (P < 0.01). In conclusion, the negative effect of N addition on litter decomposition was reversed when P was added by increasing decomposed litter soil arthropod diversity, MBC concentration, and invertase and cellulase activities. Finally, the results highlighted the important role of the N:P ratio in litter decomposition.

Advanced Biomethane Production from Biologically Pretreated Giant Reed under Different Harvest Times

Increasing energy demands and fossil fuel consumption causing global warming has motivated research to find alternative energy sources such as biofuels. Giant reed (Arundo donax L.), a lignocellulosic, perennial, rhizomatous grass has been proposed as an important bioenergy crop for advanced biofuel in the Mediterranean area. Anaerobic digestion for advanced biomethane seems to be a promising approach. However, the presence of lignin in lignocellulosic biomass represents the main obstacle to its production (due to its recalcitrance). Thus, to use effectively lignocellulosic biomass in anaerobic digestion, one or more pretreatment steps are needed to aid microorganisms access to the plant cell wall. To this end, the present study investigated the effect of fungal pretreatment of giant reeds obtained from two different harvesting time (autumn and winter) on biomethane production by anaerobic digestion using two white rot fungi (Pleurotus ostreatus and Irpex lactus, respectively). The highest biomass lignin degradation after 30 days incubation with P. ostreatus in both autumn (27.1%) and winter (31.5%) harvest time. P. ostreatus pretreatment showed promising results for anaerobic digestion of giant reed achieving a cumulative yield of 130.9 NmL g−1 VS for the winter harvest, whereas I. lacteus showed a decrease in methane yield as compared with the untreated biomass (77.4 NmL g−1 VS and 73.3 NmL g−1 VS for winter and autumn harvest, respectively). I. lacteus pretreatment resulted in a loss of both holocellulose and lignin, indicating that this strain was less selective than P. ostreatus. Further studies are necessary to identify white rot fungi more suitable to lignocellulosic biomass and optimize biological pretreatment conditions to reduce its duration.

Biomass, lignocellulolytic enzyme production and lignocellulose degradation patterns by Auricularia auricula during solid state fermentation of corn stalk residues under different pretreatments

Current work proposes an innovative substitute cultivation strategy for Auricularia auricula that connects efficient lignocellulose biodegradation of corn stalk by pretreatment with mycelium growth of Auricularia auricula under solid state fermentation. The growth promotion effect of mycelium was as follows: alkali pretreatment > alkali combined with ozone pretreatment > ozone pretreatment > high-temperature water pretreatment (control). The highest cellulose degradation (35.38%) was observed in alkali pretreatment group (P < 0.05), while the maximum lignin loss of 28.10% was reached in the ozone pretreatment group. Correlation analysis showed that both cellulose and lignin could be used as carbon sources to promote mycelium growth, but the effect of cellulose was better. High activities of β-glucosidase (2.92 IU/g) and filter paper enzyme (2.92 IU/g) were observed in alkali pretreatment group on Day 6 and 8, respectively, which were significantly correlated with the change of cellulose degradation rate (P < 0.01).

Canopy structure and phenology modulate the impacts of solar radiation on C and N dynamics during litter decomposition in a temperate forest

Decomposition of plant organic matter plays a key role in the terrestrial biogeochemical cycles. Sunlight has recently been identified as an important contributor to carbon [C] turnover through photodegradation, accelerating decomposition even in forest ecosystems where understorey solar irradiance remains relatively low. However, it is uncertain how C and nutrients dynamics respond to fluctuations in solar spectral irradiance caused by canopy structure (understorey vs. gaps) and season (open vs. closed canopy phenology). Spectral-attenuation treatments were used to compare litter decomposition over eight months, covering canopy phenology, in a temperate deciduous forest and an adjacent gap. Exposure to the full spectrum of sunlight increased the loss of litter C and lignin by 75% and 64% in the forest gap, and blue light was responsible for respectively 27% and 42% of that loss. Whereas in the understorey, C and lignin loss were similar among spectral-attenuation treatments over the experimental period, except prior to and during spring canopy flush when exposure to the full spectrum of sunlight promoted C loss by 15% overall, 80% of which was attributable to ultraviolet-B (UV-B) radiation. Nitrogen [N] was immobilized in the understorey during canopy flush before the canopy completely closed but N was swiftly released during canopy leaf-fall. Our study suggests that blue-driven photodegradation plays an important role in lignin decomposition and N dynamics in canopy gaps, whereas seasonal canopy phenology affecting sunlight reaching the forest floor drastically changes patterns of C and N in litter during decomposition. Hence, including sunlight dynamics driven by canopy structure and phenology would improve estimates of biogeochemical cycling in forests responding to changes in climate and land-use.

INDIVIDUAL AND INTERACTIVE EFFECTS OF PEROXIDE PRETREATMENT VARIBLES ON SACCHARIFICATION AND ETHANOL YIELD IN BAGASSE

The current experiment aimed to find the ideal pretreatment process parameters for maximize the yields of cellulose, fermentable simple sugars, and ethanol from bagasse that had successfully treated with hydrogen peroxide (H2O2). The pretreatment process variables like substrate concentration, H2O2 concentration, pretreatment time, and temperature were studied individually and in combination to see how they affected the response variables like cellulose, hemicellulose, and lignin content in the pretreated pulp. This was done using the response surface methodology (RSM). The best pretreatment conditions for sugar cane bagasse were found through experiments using a factorial central composite design (CCD). The highest cellulose and hemicellulose yields, which were determined by RSM to be 69.3% and 76.4%, respectively, with a lesser lignin yield (4.8%), were achieved at a substrate concentration of 2%, an H2O2 loading of 20%, a temperature of 120 oC, and a pretreatment duration of 120 min. The experimental actual and predicted outcomes were well correlated, demonstrating that the model may be applied to effectively pretreat lignocellulosic biomass. The model has been validated when there is no difference between experimental actual values and anticipated values. The modifications in the chemical structure of bagasse during pretreatment was analyzed using FTIR. Comparatively, samples processed with H2O2 had a higher crystallinity (CI = 23.63%) than untreated bagasse (CI = 15.84%). The loss of lignin, which contributed the greatest CrI, increased the proportion of cellulose in treated bagasse compared to untreated bagasse. The bagasse that had a H2O2 concentration pretreatment showed the highest reducing sugar yield (58.7 mg/g). Pretreated bagasse had a higher ethanol output (73.88 g/L) than untreated bagasse (45.49 g/L).