Rice Straw Hemicellulose Research Articles

Preservation of freshly-cut lemon slices using alginate-based coating functionalized with antioxidant enzymatically hydrolyzed rice straw-hemicellulose

Food coatings are efficient preservative measures, a crucially needed approach to meet hunger growth as well as food management. In the current study, the construction of an efficient coating using alginate polymer fortified with antioxidant rice straw-hemicellulose hydrolysate was examined. Rice straw hemicellulose fraction was extracted under thermal alkaline conditions with a recovery percentage of 15.8%. The extracted hemicellulose fraction was enzymatically hydrolyzed with microbial xylanase with hydrolysis percentage of 53.8%. Characterization of the produced hydrolysate was performed with the aid of thin layer chromatographic analysis (TLC), high-performance liquid chromatographic analysis (HPLC), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) analysis. The reported data showed that xylobiose (240.68 mg/g) in addition to coumaric (383.33 µg/g) and ferulic acid (298.77 µg/g) as the main constituents of the carbohydrate and the polyphenolic contents, respectively. The hydrolysate possessed antioxidant capacity that significantly increased in a direct correlation with the concentration of the hydrolysate. Finally, the prepared coating solution effectiveness in the preservation of lemon slices against fungal growth was monitored up to 20 days with a significant concentration dependent decrease in weight loss and an increase in its antioxidant activity. The combination of xylooligosaccharide-rich rice straw hydrolysate with alginate-based coating not only improved the storage shelf-life of fresh fruits and vegetables but also provided microbial safety and potential benefits for human health.

Chemical Composition And Surface Images Of Untreated And Urea-Treated Rice Straw As Inf uenced By Days After Threshing

The purpose of this study was to evaluate the chemical composition and changes in the surface structure of rice straw as affected by the number of days of exposure to the field prior to processing. A total of 24 packs of rice straw samples collected at 1 day after threshing (DAT), 4 DAT, and 7 DAT field exposure untreated and treated with urea for 10 days were analyzed for its chemical changes using proximate analysis and surface structure of the fiber compounds through scanning electron microscopy (SEM). Results (%DM basis) showed that 1DAT untreated rice straw obtained the highest dry matter (DM) concentration at 94.61%. Seven DAT untreated rice straw contain the highest amount of Ash at 20.92%. Likewise, 1 DAT and 7 DAT untreated rice straw contains higher levels of crude protein (CP) at 9.60% and 9.79%, respectively. Ether extract (EE) was observed highest in 1DAT untreated rice straw at 1.97%. Considerable breakdown of cellulose, hemicellulose, and lignin fractions of rice straw was attained in 4DAT and 7DAT untreated, and 1 to 7 DAT urea-treated rice straw (UTRS) as evident by its lower NDF, ADF, and ADL values. Changes in the surface structures of microfibers efficiently captured using SEM showed the differences in the morphology of the fibers as influenced by number of days exposed to the field prior to treatment. Therefore, in order to optimize the protocol to improve the feeding and nutritional quality of rice straw, it is suggested that the number of days of exposure to the field be considered prior to processing. Likewise, UTRS is an effective method to disintegrate the complex fibrous compounds of the cell wall of rice straw.

Differentiated Fractionation of Various Biomass Resources by p-Toluenesulfonic Acid at Mild Conditions.

Biomass is the ideal substitute for petrochemical resources because of its renewable and abundant sources. p-Toluenesulfonic acid (p-TsOH) can effectively separate lignin from biomass under mild conditions, so it is highly expected in biomass fractionation to improve the utilization efficiency. In this study, we investigated the effect of p-TsOH differentiated fractionation of poplar sawdust, eucalyptus sawdust, and rice straw below 100 °C. According to the experimental results, upon pretreatment by p-TsOH of the three kinds of raw biomass, most of the lignin and hemicellulose of poplar sawdust and eucalyptus sawdust were removed, whereas the cellulose was retained, but most of the hemicellulose and cellulose of rice straw were kept, whereas the lignin was removed at similar conditions. The structures and compositions of pretreatment residues, lignin, and hemicellulose extracted from raw biomass were characterized by XRD, FTIR, HSQC-NMR, XPS, and SEM. The differentiated fractionation mechanism of biomass was analyzed. A better recognition and understanding of the factors affecting biomatrix opening and fractionation will allow for the identification of new pretreatment strategies that improve biomass utilization and permit the rational enzymatic hydrolysis of cellulose.

Integrated hydrothermal and deep eutectic solvent-mediated fractionation of lignocellulosic biocomponents for enhanced accessibility and efficient conversion in anaerobic digestion

Effective fractionation of lignocellulosic biocomponents of lignocellulosic biomass can increase its utilization in anaerobic digestion for high yield biomethane production. A hydrothermal process was optimized and integrated with a deep eutectic solvent (DES) pretreatment to preferentially fractionate hemicellulose, cellulose, and lignin in rice straw. The optimized hydrothermal process resulted in 96% hemicellulose solubilization at moderately low combined pretreatment severity (log S = 2.26), allowing increased hemicellulosic sugar recovery with minimal formation of inhibitory byproducts. Subsequent DES pretreatment resulted in highly bioaccessible cellulosic pulp, removing 81.3% of lignin that can be recovered and converted into value-added products. Anaerobic digestion of hemicellulosic fraction and cellulosic pulp using a microbial methanogenic consortium seed acclimatized to the lignocellulosic inhibitors resulted in a 33.4% higher yield of methane (467.84 mL g−1 VSinitial) than with anaerobic digester sludge seed. This integrated approach can facilitate and maximize the targeted utilization of different biocomponents through sustainable biorefining.

Lignin degradation by water buffalo.

So far, few animals with the ability of lignin degradation have been reported except termite and longicorn. In this study, it was found that the crude fiber and acid detergent lignin (ADL) of rice straw can be degraded dramatically higher by buffalo than those by cattle. In order to further study this ability of buffalo, the digestion of roughages in buffalo rumen was studied using rumen nylon bag experiment, scanning electron microscopy (SEM), and Van Soest fiber analysis. The SEM results showed that the degradation degree of rice straw was dramatically higher in buffalo than that in cattle. The digestibility of crude fiber was significantly higher in buffalo than that in cattle (P < 0.01). The digestibility of ADL, cellulose, hemicellulose, acid detergent, fiber, and neutral detergent fiber of rice straw in buffalo rumen was significantly higher than that in cattle (P < 0.05). The ADL degradation rate of rice straw in buffalo rumen was significantly higher than that in cattle rumen, indicating that buffalo was capable of utilizing lignin and had superior utilizing capability than cattle. It was observed that various roughages can be dramatically digested by buffalo rumen with the ranking of ADL degradation rate: peanut vine (15.04%) > rice silage > maize silage > rice straw > corn stover > wheat stalk > bract leaf > potato vine (7.22%), verifying that buffalo rumen possessed the ability to digest universal roughages. In conclusion, this study revealed that buffalo was more efficient in ADL degradation compared with cattle.

Production of Xyloligosaccharides from Rice Straw by Microwave-assisted Enzymatic Hydrolysis and Evaluation of Their Prebiotic Properties

Rice straw (RS) is a by-product from rice production process. It is rich in cellulose, hemicellulose and lignin. RS hemicellulose mainly composes of arabinoxylan (AX). This research aimed to investigate the potential of microwave-pretreatment in AX extraction from RS and substrate to produce xylooligosaccharides (XOS) via enzymatic hydrolysis. The extractive-free RS was pretreated by microwave process at 160°C for 5-15 min, then the AX was extracted with 4% sodium hydroxide. The total sugar and reducing sugar content of AX exhibited that increasing microwave-pretreatment time increased the yield of AX. The highest AX content was found at 160°C for 10 min as 7.73%, reducing sugar content of 11.89 mg/g, and total sugar of 165.85 mg/g. The crude AX obtained by microwave-pretreatment was then used as a substrate for XOS production by two commercial xylanases of Pentopan mono BG (BG) and Ultraflo Max (UM), at the enzyme concentration of 50-300 U/g AX (50°C, pH 6.0) for 24 h.The reducing sugar content and sugar profiles were monitored by DNS assay,and thin layer chromatography (TLC) which revealed that BG 50 U/g at 12 h andUM 50 U/g at 24 h showed the promising reducing sugar of 16.4 and 25.44 mg/g,respectively. The composition of XOS derived from RS (RS-XOS) prepared by BGwas xylobiose (X2), xylotriose (X3), xylotretraose (X4), and xylopentaose (X5)while by UM was xylobiose (X2), xylotriose (X3) and xylotretraose (X5). Moreover,XOS produced by BG contained very low amount of xylose (X1). In addition, theRS-XOS could the growth of Lactobacillus brevis greater than commercial XOS.

Biotechnological potential of cellulolytic nitrogen-fixing Klebsiella sp. C-3 isolated from paddy soil

In the present study, a new thermo-adaptive cellulolytic nitrogen-fixing bacterial strain designated as Klebsiella sp. C-3, which could degrade cellulose and hemicellulose in rice straw (RS) without an added nitrogen source, was isolated from paddy soil. The highest activities of enzymes (FPase, 0.92 IU/mL, and Xylanase, 17.1 IU/mL) produced by Klebsiella sp. C-3 were recorded at 37 °C. In RS hydrolysate, the % of the total nitrogen content increased from 0.65% to 3.7% after 7-day fermentation with Klebsiella sp. C-3. The main reducing sugar products of RS hydrolysate were glucose, xylose, and cellobiose. Unexpectedly, Klebsiella sp. C-3 had much lower water loss (30%) than the control group (61.85%) and other bacterial isolates at 45 °C after a 7-day incubation period. Hence, Klebsiella sp. C-3 could provide a feasible pathway to manage lignocellulosic biomass in soil and improve water retention in thermophilic biological processes and arid soils.

Efficient and Selective Catalytic Conversion of Hemicellulose in Rice Straw by Metal Catalyst under Mild Conditions

Rice straw is an abundant material with the potential to be converted into a sustainable energy resource. Transition-metal catalysis activated the C–O bond in the hemicellulose of raw rice straw, cleaving it to form monosaccharides. The mechanism of rice straw catalytic conversion had a synergistic effect due to in situ acid catalysis and metal catalysis. The conditions for the hydrogenation of hemicellulose from rice straw were optimized: catalyst to rice straw solid/solid ratio of 3:10, stirring speed of 600 r/min, temperature of 160 °C, time of 3 h, solid/liquid ratio of 1:15, and H2 gas pressure of 1.5 MPa. An excellent hemicellulose conversion of 97.3% with the yields of xylose and arabinose at 53.0% and 17.3%, respectively, were obtained. The results from FTIR and SEM experiments also confirmed the destruction of the rigidity and reticulate structure of rice straw after the catalytic reaction.

A novel integrated process to convert cellulose and hemicellulose in rice straw to biobutanol

A novel integrated process was established in this study to produce butanol from rice straw. In the first pretreatment, an alternative NaOH/Urea preatment operated at −12 oC efficiently removed 10.9 g lignin and preserved 91.54% cellulose and hemicellulose in 100 g rice straw. Subsequently, crude cellulase produced from Trichoderma viride was used to convert pretreated rice straw to mono-sugars for fermentation. The yields of glucose, xylose and arabiose obtained from 100 g rice straw were 31 g, 13.4 g and 0.48 g, respectively, resulting in a 69.45% saccharification efficiency of crude enzyme. Finally, to alleviate the carbon catabolite repression (CCR) and enhance butanol production, the coculture system of Clostridium beijerinckii and Saccharomyces cerevisiae was applied. Compared to monoculture of C. beijerinckii F-6, more sugars were consumed, especially the reduction rate of xylose reached to 81.87%, 32.99% higher than that in monoculture system. With more substrate facilitied into metabolism, the butanol concentration reached to 10.62 g/L corresponding to 0.28 g/g substrate, 115.38% higher than that in monoculture system. Overall, this integrated process was a low-energy consumption and efficient method for butanol production from rice straw.

Evaluation of Rice Straw Yield, Fibre Composition and Collection Under Mediterranean Conditions

Abstract Rice straw remains almost unutilised in the majority of cases and is usually burned. Data on rice residue production under European conditions are extremely limited. A detailed assessment of rice biomass yield, partitioning and straw collection was carried out in Spain. Eleven commercial rice varieties were evaluated in 2015, and two baling trials were performed in 2014 and 2015. The average straw yield was 9.7 t·ha−1. Straw yield, biomass partitioning indices and fibre composition varied significantly according to rice variety. Straw to grain ratio and harvest index were 1.00 and 0.50 on average for rough grain, and 1.25 and 0.41 for husked grain. Biomass partitioning indices significantly correlated with grain yield. Mean content of cellulose, hemicellulose, lignin and ash of rice straw was 32.5%, 19.8%, 6.5% and 13.7%, respectively. Straw amount of less than 3.0 t·ha−1 can be collected during the baling trials. Rice straw could represent an eco-friendly source of lignocellulosic biomass in Europe, however, in order to achieve this, baling machine improvements and special crop management should be carried out.

Solid state fermentation process coupled biological pretreatment with cellulase production by Piptoporus betulinus for enhanced cellulose hydrolysis

An integrated process of cellulase production and pretreatment employing Piptoporus betulinus was proposed to accomplish economic feasibility of lignocellulosic ethanol. After 24 days of cultivation, the maximum loss of weight and hemicellulose of rice straw was 21.25% and 24.79%, respectively. The cellulose was degraded slightly and exposed. Furthermore, the modified lignin led to the weak interaction between lignin and hemicellulose. The optimized enzyme production for CMCase activity (58.37 U g−1 substrate) and FPase activity (7.43 U g−1 substrate) were obtained on the 12th day and the 18th day, respectively. Whereas, the highest reducing sugar yield of rice straw (392.96 mg g−1) was obtained on the 24th day, which was 2.82 times higher than that of the control with the reduced cellulase dosage of 37.15%. In this study pretreatment, cellulase production and enzymatic hydrolysis were coupled into one process, which opens an avenue for environmentally friendly and cost effective technology in lignocellulosic ethanol production.

Peningkatan Kualitas Jerami Padi MenggunakanTeknologi Amoniasi Fermentasi

An experiment with aim to study the effect of probiotics combination level and length of fermentation on qualityimprovement of rice straw had been conducted at the Laboratory of Nutrition and Feed of Animal HusbandryFaculty, Mataram University. The research was arranged in a Completely Randomized Design in factorialarrangement 3 x 3 with 3 replications. The first factor was the level of probiotics (0, 2 and 4%), the second factorwas the period of fermentation (2, 4 and 6 weeks).The variables measured were crude protein, crude fiber, NDF,ADF, cellulose, hemicellulose, lignin, and in vitro digestibility of dry matter and organic matter. Data wereanalyzed by analysis of variance and tested further by Duncan's Multiple Range Test. The result show thattreatments combination of the probiotics level and fermentation period did not affect (P&gt;0.05) the chemicalcomposition and digestibility. The level of probiotics increased (P&lt;0.05) the crude protein and in vitro dry matterdigestibility. Meanwhile, the lenght of fermentation increased the crude protein and in vitro digestibility of drymatter and organic matter, but decreased the crude fiber, NDF, ADF, cellulose, and hemicellulose of Amofer ricestraw.

The Effect of NaOH Concentration and microwave exposure time to the content of cellulose, hemicellulose and lignin of Corn Cob

Abstract.Currently ethanol produced from molasses, cassava and maize, thereby competing with the need for food, animals feed and other industrial raw materials, so that the supply of raw materials is not continuity. If this continues, it will certainly have an impact on food prices spike, it will create new problems on the economy of the community, and one of an alternative raw material for bioethanol production is cellulose biomass.To convert biomass into bioethanol through several stages, including pretreatment, hydrolysis and fermentation. The content of lignin in biomass will disturb the enzymatic hydrolysis process, so it is necessary to encourage the delignification in the pretreatment stage. Microwave - alkali pretreatment can reduce more lignin and hemicellulose in rice straw, so it needs to be an effort to change the composition of lignocellulose and improve the hydrolysis of corn cob is fermented to become ethanol. Pretreatment of corn cobs research was done using randomized block design arranged in factorial and repeated 2 times. The first factor is the concentration of NaOH for 0,5 N, 1 N and 1,5N. The second factor is the time of exposure to microwave heat radiation for 10, 20 and 30 minutes. The results showed that cellulose content increases with prolonged exposure concentrations of NaOH and microwave, as well as to the content of hemicellulose and lignin decreased along with the increase of exposure duration of Microwave and the increase of NaOH concentrations.

English

Abundance and unmanaged agriculture residues lead to unutilized resource waste and environmental pollution. Application of microbial technology to manage agriculture waste could produce value-added product. A preliminary study on biodegradation of rice straw using different potential microorganisms was tested under controlled environment. Three different inoculant cultures were used to observe their efficiency in rice straw degradation. Combination cultures microorganisms coding AMB1 shows the potential degrading activity, which reduces the hemicellulose of rice straw by 50% from the raw material. The highest cellulase activity at 1.5 U/mL was also observed in rice straw treatment with AMB1 than single inoculant fungi and commercial microbial product. Overall, the results suggested that the biodegradation of rice straw could be improved by using combination culture. The ability of these cultures to enhance biodegradation shows potential to fasten the decomposing period and may be used to manage agriculture waste. Key words: Cellulase, lignin, agriculture waste, biodegradation.

Novel Butyric Acid Fermentation Strains and Their Performance in Fermenting Rice Straw by Pure and Mixed Culturing

Synergistic metabolism among mixed culture can be utilized to hydrolise and ferment cellulose and hemicellulose in rice straw to avoid high cost of saccharification and its complex procedure. Three buryric acid producing strains cellulose-decomposing bacteria named Clostridium cadaveris C4, cellubiose fermenting bacteria named C. butyricum B20, xylan-degrading bacteria named C. butyricum X3 respectively were isolated from undefined mixed culture which was enriched and cultured from rice straw. The fermentation experiment of rice straw was carried out to increase the burytic acid conversion rate with three single strain and their mixed strains. Fermentation results showed that co-fermentation with two or three strains can significantly improve the degradation of rice straw and yield of butyric acid because of synergistic effect in or among different metabolic strains. Among the experiment, co-culture of three strains with inoculum of 1.1 g-DCW/L got the butyric acid production rate 0.18 g/(g-DCW×h) during logarithmic period which increased by 50%, 200% and 63.64% compared with C4, B20 and X3 respectively.The results of the study provide the methodological guidance and bacterial strain resources for the butyric acid biotransformation from lignocellulosic biomass.

Study on the Characteristics of Straw Fermentation by Bacillus megaterium MYB3

Corn stover and rice straw fermentation were carried out using Bacillus megaterium MYB3. The decomposition rates of cellulose and hemicellulose were analyzed at d3, d5, d10, d20. Organic acid concentration was determined by HPLC. The decomposition rates of cellulose and hemicellulose in corn stover were 54.29% and 48.21% in 20 days respectively. The decomposition rates of cellulose and hemicellulose in rice straw were 44.87% and 29.32%. Concentration of lactic acid was increased in the fermentation of corn stover and rice straw. And acetic acid was increased and then decreased. The concentration of propionate and butyric acid were measured after 10 days in the corn stover. Butyric acid was decreased from original concentration in 10 days at rice straw.

Alkaline deacetylation as a strategy to improve sugars recovery and ethanol production from rice straw hemicellulose and cellulose

A mild alkaline pretreatment (deacetylation) prior to the dilute acid pretreatment was evaluated as a strategy to improve the sugars recovery and ethanol production from both hemicellulose and cellulose fractions of rice straw. This pretreatment was carried out using different conditions of temperature (50–70°C) and NaOH loading (20–80mg NaOH/g biomass), which were combined according to a 22 central composite design. In this step the removal of acetyl groups as well as the impact of this step on biomass composition were evaluated. In order to assess the impact of the deacetylation on hemicellulosic hydrolysate composition, the influence of the reaction time (30–90min) and sulfuric acid concentration (0.5–1.5% w/v) was also studied, using the alkaline-pretreated solid (deacetylated) and rice straw in natura. The best sequential pretreatment conditions were scaled-up to 50-L reactor, being obtained a cellulose-rich pretreated solid (cellulignin) and a hemicellulosic hydrolysate, which was concentrated to 70g/L xylose to be used as fermentation medium. A significant improvement on ethanol production from xylose by Scheffersomyces stipitis NRRL Y-7124 was observed when the biomass was submitted to deacetylation (about 4-fold). The enzymatic conversion of cellulose was also improved (from 73 to 89%) when the deacetylated cellulignin was used, resulting in an enhancement of the ethanol production (from 12.7 to 20.4g/L) during the simultaneous saccharification and fermentation with Kluyveromyces marxianus NRRL Y-6860. In brief, biomass deacetylation prior to dilute acid pretreatment was an efficient strategy for rice straw processing, substantially improving the ethanol production from both pentose and hexose sugars.

Assessment of advanced oxidative processes based on heterogeneous catalysis as a detoxification method of rice straw hemicellulose hydrolysate and their effect on ethanol production by Pichia stipitis

In the present work, detoxification treatments based on advanced oxidative processes (AOPs) aiming to improve the ethanol production by Pichia stipitis were evaluated. The experimental design was carried out according to a Taguchi L8 orthogonal array in order to evaluate the influences of pH, catalyst type (ZnO or TiO2), UV radiation (UVA or UVC), and oxidant agent (O2 or O3) on aromatic compounds concentration and fermentation performed. The results showed that treatment conditions which most contribute to reducing the toxicity of the hydrolysate in relation to ethanol production were pH 8.0 and the use of O3 as an oxidizing agent. Within the region evaluated, there was no difference between the use of TiO2 or ZnO and or UVA or UVC radiation. The heterogeneous AOPs were able to remove above 49 % of the furan, above 39 % of the total phenolic compounds, and 100 % of the low molecular weight phenolic compounds, without affecting the sugar concentrations in the hydrolysate. Furthermore, heterogeneous processes have provided relevant increases on sugars consumption (148 %) and maximum ethanol concentration (154 %) as compared with untreated hydrolysate. In addition, the AOPs treatment showed advantages such as it does not generate waste, does not degrade hydrolysate sugars, and does not lead to loss of hydrolysate volume due to the treatment. Based on the results, it can be concluded that AOPs are promising processes for application in hydrolysate treatment to reduce toxicity and consequently improve the fermentability of lignocellulosic hydrolysates.

Metabolizable energy and fiber digestibility of uncommon feedstuffs for geese

This experiment was conducted to study the digestibility of uncommon feedstuffs for geese. Thirty Taihu ganders were selected and divided into 5 groups (n = 6), and one group was allocated as the control. Taihu ganders in the 4 treated groups were force-fed with a weight of different uncommon feedstuffs after 24 h of fasting, and the control group was kept in fasting with no force feeding. All excretion of each gander was collected on a plate for 24 h after force feeding. There was a 12-d recovery period between treatments. In this study, we measured the ME and analyzed neutral detergent fiber, acid detergent fiber, and hemicellulose of brewers grains, distillers grains, empty-grain rice, ryegrass powder, rice husk, corn stalk, rice straw, wheat straw, wheat husk, mushroom bran, and peanut vine. The TME values were 9.29, 8.67, 8.97, 5.89, 3.85, 3.10, 3.32, 3.02, 5.29, 2.48, and 3.15 MJ/kg, respectively. The digestibility of neutral detergent fiber for the feedstuffs ranged from 6.14 to 45.0%, the digestibility of acid detergent fiber ranged from 4.52 to 32.6%, and the digestibility of hemicellulose ranged from 18.5 to 61.6%. The best TME quadratic prediction equation was TME = 12.2 - 0.232CF, where CF is crude fiber. These results suggest that geese were able to use uncommon feedstuffs with high digestibility, and there was a significant negative correlation between energy digestibility and CF content. The ME values tested in this experiment can provide a foundation for preparation and adjustment of feed formulation for reasonable use of uncommon feedstuffs for geese.

Pretreatment of Rice Straw by Hydrogen Peroxide for Enhanced Methane Yield

A pretreatment process for hydrogen peroxide (H2O2) was optimized to enhance the biodegradation performance of rice straw and increase biogas yield. A determination experiment was conducted under predicted optimal conditions. Optimization was implemented using response surface methodology. The effects of biodegradation and the interactive effects of pretreatment time (PT), H2O2 concentration (HC), and substrate to inoculum ratio (S/I) on methane yield were investigated. The lignin, cellulose, and hemicellulose of rice straw were significantly degraded with increasing HC. The optimal conditions for the use of pretreated rice straw in anaerobic digestion were a 6.18-d PT, 2.68% HC (w/w total solid), and 1.08 S/I; these conditions result in a methane yield of 288 mL g−1 volatile solids (VS). A determination coefficient of 95.2% was obtained, indicating that the model used to predict the anabolic digestion process has a favorable fit with the experimental parameters. The determination experiment resulted in a methane yield of 290 mL g−1 VS, 88.0% higher than that of untreated rice straw. Thus, H2O2 pretreatment of rice straw can be used to improve methane yields during biogas production.