Treated Rice Straw Research Articles

EFFECT OF UREA AND/OR CRUDE GLYCERIN TREATMENT ON THE NUTRIENT COMPOSITION AND IN VITRO TRUE DIGESTIBILITY OF DIFFERENT VARIETIES OF RICE STRAW

This study aimed to evaluate the nutrient composition and in vitro true digestibility of three rice straw (RS) varieties with varying stem lengths (Vasco (V): short-stemmed, Cammeo (C): medium-stemmed, and Efe (E): long-stemmed) treated with urea and/or crude glycerin. Each RS variety was ensiled in laboratory-scale mini-silos for 30 days using the following treatments: i) Control, ii) 5 % urea (U) treated RS, iii) 5 % crude glycerin (G) treated RS, and iv) 5% urea + 5% crude glycerin (UG) treatment RS. The Vasco variety of RS exhibited superior nutritional value compared to the Cameo and Efe varieties, with a greater (P<0.05) in vitro true digestibility of dry matter (IVTDDM (V:46.11%, C:41.17% and E:43.94%) as well as lower (P≤0.001) NDF (V:66.38%, C:71.68%, and E:68.59%) and ADF (V:43.61%, C:50.64%, and E:49.1%) levels. Silage of all cultivars demonstrated comparable responses to the applied treatments. The crude protein (P<0.001) and IVTDDM (P<0.001) were greater in all treatment groups where urea was used alone or in combination with crude glycerin. All cultivars showed a reduction in NDF (P<0.001) and ADF (P<0.001) levels with the application of crude glycerin treatment alone, but no significant effect was observed on IVTDDM values. In the interaction effect, Efe×UG showed higher (P<0.001) in vitro true digestibility while for in vitro NDF digestibility, Efe×U interaction exhibited higher (P<0.001) digestibility compared to other interaction effects. The findings of the study suggest that adding urea or a combination of urea and glycerin to rice straw improved its nutritional content and digestibility. Treating rice straw with a combination of urea (5%) and glycerin (5%) could be a promising strategy to improve its nutritional value for livestock feed. Keywords: crude glycerin, digestibility, rice straw, silage, treatment, urea

Solvent self-doping synthesis of nitrogen/oxygen co-doped porous carbon from cellulose as high performance material for multipurpose energy storage

Developing novel heteroatoms co-doped biomass porous carbon with low-cost, tunable physical/chemical properties, and environmental friendliness is an important candidate to face energy shortage and environmental pollution currently. Herein, a novel solvothermal avenue was designed using triethanolamine as self-doping solvent to treat rice straw powders with KOH. The rice straw with triethanolamine derived carbon (RSTCs-1) possessed hierarchical porous structure, N/O diatomic doping, and large specific surface area. The electrochemical energy storage performance of RSTCs-1 was evaluated in the systems of supercapacitors, aqueous zinc ion hybrid supercapacitors (AZHSs), and lithium-ion batteries (LIBs) respectively. As the results, the RSTCs-1 based symmetric supercapacitor exhibited the maximum energy density of ca. 98.4 Wh·kg−1 with the excellent cycling stability. Moreover, both RSTCs-1 AZHSs and RSTCs-1 LIBs achieved the relative high discharge specific capacities of ca. 407.1 and 1906.7 mAh·g−1 at current density of 0.1 A·g−1. These results highlighted the huge potential of the obtained with notable electrochemical performance acting as multifunctional electrode material for the different energy storage devices.

Straw Incorporation with Exogenous Degrading Bacteria (ZJW-6): An Integrated Greener Approach to Enhance Straw Degradation and Improve Rice Growth.

Rice straw is an agricultural waste, the disposal of which through open burning is an emerging challenge for ecology. Green manufacturing using straw returning provides a more avant-garde technique that is not only an effective management measure to improve soil fertility in agricultural ecosystems but also nurtures environmental stewardship by reducing waste and the carbon footprint. However, fresh straw that is returned to the field cannot be quickly decomposed, and screening microorganisms with the capacity to degrade straw and understanding their mechanism of action is an efficient approach to solve such problems. This study aimed to reveal the potential mechanism of influence exerted by exogenous degradative bacteria (ZJW-6) on the degradation of straw, growth of plants, and soil bacterial community during the process of returning rice straw to the soil. The inoculation with ZJW-6 enhanced the driving force of cellulose degradation. The acceleration of the rate of decomposition of straw releases nutrients that are easily absorbed by rice (Oryza sativa L.), providing favorable conditions for its growth and promoting its growth and development; prolongs the photosynthetic functioning period of leaves; and lays the material foundation for high yields of rice. ZJW-6 not only directly participates in cellulose degradation as degrading bacteria but also induces positive interactions between bacteria and fungi and enriches the microbial taxa that were related to straw degradation, enhancing the rate of rice straw degradation. Taken together, ZJW-6 has important biological potential and should be further studied, which will provide new insights and strategies for the appropriate treatment of rice straw. In the future, this degrading bacteria may provide a better opportunity to manage straw in an ecofriendly manner.

Enhanced production of lactic acid from pretreated rice straw using co-cultivation of Bacillus licheniformis and Bacillus sonorenesis.

Lactic acid (LA) production from sugar mixture derived from lignocellulosic rice straw employing co- culture system of thermotolerant and inhibitor tolerant Bacillus licheniformis DGB and Bacillus sonorenesis DGS15 was carried out. In minimal media, both the strains of Bacillus DGB and DGS15 worked together by efficiently utilising glucose and xylose respectively. Response Surface Methodology (RSM) was used for optimisation of pretreatment of rice straw to achieve maximum yield of 50.852g/L total reducing sugar (TRS) from 100 gm of rice straw biomass. Pretreatment of rice straw resulted in its delignification, as confirmed by FTIR spectroscopy, since the peak at 1668cm-1 disappeared due to removal of lignin and scanning electron microscopy (SEM) revealed disruption in structural and morphological features. Crystallinity index (CrI) of treated rice straw increased by 15.54% in comparison to native biomass. DGB and DGS15 individually yielded 0.64g/g and 0.82g/g lactic acid respectively, where as their co-cultivation led to effective utilisation of bothglucose and xylose within 15h (70%) and complete utilisation in 48h, producing 49.75g/L LA with a yield of 0.98g/g and productivity of 1.036g/L/h, andresulting in reduction in fermentation time. Separate hydrolysis of rice straw and co-fermentation (SHCF) of hydrolysates by Bacillus spp. enhanced the production of lactic acid, can circumvent challenges in biorefining of lignocellulosic biomass.

Incubation temperature affects growth and efficacy of white-rot fungi to improve the nutritive value of rice straw

Context A great body of evidence is available on the in vitro efficacy of white-rot fungi (WRF) to degrade lignin in fibre-rich biomass (e.g. wheat straw, wood chips and rice straw (RS)) and improve the biomass’ nutritive value for ruminants. Aims Determining the impact of incubation temperature of three WRF to improve the nutritional value of rice straw. Methods Growth of Ceriporiopsis subvermispora, Lentinula edodes and Pleurotus eryngii on RS for 26 days at the following six temperature regimes: continuous at 24°C, 30°C, 35°C and 40°C, and 3 days at 35°C and 40°C, with subsequent days at 24°C. In a follow-up experiment, improvement in fermentability in buffered rumen fluid of RS treated by the three WRF at 24°C and 30°C for up to 8 weeks was investigated. Key results All three fungi grew at temperatures up to 35°C, with no growth observed at 40°C, with C. subvermispora being more temperature sensitive. There were significant differences in cellulose, hemicellulose and lignin degradation of RS at 24°C and 30°C, with C. subvermispora degrading 69% and 90% of the hemicellulose and lignin respectively at 30°C, greater than at 24°C (55% and 80% respectively). For L. edodes, there were significant differences in cellulose degradation between 24°C and 30°C, with 12% more degradation at 30°C, but not for hemicellulose and lignin. In vitro gas production showed no significant differences between the two incubation temperatures for either of the two fungi. Pleurotus eryngii treatment did not show any improvement in terms of in vitro gas production. Conclusions Treatment of RS with L. edodes and C. subvermispora, but not P. eryngii, is robust and temperature changes will not have a major impact on their efficacy as long as the temperature remains below 30°C. Implications Temperature during the incubation of WRF with rice straw needs to be below 30°C for this biotechnology to be applied in practice.

EFFECT OF RICE STRAW ON SOME BLOOD BIOCHEMICAL PARAMETERS OF IRAQI BUFFALO (Bubalus Bubalis)

This study was aimed to show the changes of some blood parameters by the effect of biological and chemical treatment of rice straw ,It was conducted at The Ruminant Research Station in Abu Ghraib / Directorate of / Agricultural Researches / Ministry of Agriculture, for the period from June 1, 2021 until August 27, 2021 (preceded by the preliminary period 14 days), The study included 12 Iraqi buffalo calves aged 5 - 6 months. the calves were randomly divided into three equal groups (4 calves / group), kept in individual pens and distributed among group.T1 (the control group) in which the calves were fed on untreated rice straw T2 the calves were fed on rice straw treated with urea at a rate of 3% T3 the calves were fed on rice straw treated with Trichoderma harzianum at a rate of 0.1%. The triglycerides concentration were decreased significantly (p≤0.05) in the T2 (11.28 mg/dL) and T3 (11.32 mg/dL) compared with T1 (20.79 mg/dL). similarly, the level of very low-density lipoprotein (vLDL) was decreased 2.25, 2.26, 4.16 mg/dL for T2, T3, and T1, respectively. The creatinine concentration in T2(87.19 mmol/L) was significantly decrease than that of T1(177.8 mmol/L) and T3(176.75 mmol/L). Also, ALP concentration increased in T2 (238.93 IU/liter) compared with T1. (151.82 IU/liter), while it did not differ significantly with T3( 205.83 IU/liter) Also T3 did not differ significantly from T1. The differences in the concentration of lipid profile, protein fractions and enzymes activity among groups lacked significance , feeding of rice straw treated biologically and chemically had no negative effect on buffalo calves health.

Rice Straw‐Derived Biochar as Anode Material for Lithium‐Ion Battery: A Step toward Sustainable Development

In the present study, sustainable upscaling of rice straw, an agri‐residue, is explored as the way to obtain active material to prepare anode for use in lithium‐ion batteries (LIBs). The biochar having high carbon and low silica content is prepared by initial chemical treatment of rice straw followed by its pyrolysis. The pristine and modified biochar are characterized using Brunauer‐Emmett‐Teller surface area, energy dispersive X‐ray spectroscopy, carbon hydrogen nitrogen sulphur elemental analysis, scanning electron microscopy, X‐Ray power diffraction, Fourier transform infrared spectroscopy and Raman analysis and the modified biochar show an enhancement in graphitic carbon content. A coin cell is assembled using anode prepared from modified biochar. The coin cell is subjected to electrochemical testing and had a discharge capacity of 352 mA.h g−1. Further, the coin cell is tested for 100 cycles and a columbic efficiency of 99.7% was obtained. Therefore, biochar derived from pyrolysis of rice straw has the potential to be used as anode material for LIBs.

Chemical composition and in vitro neutral detergent fibre digestibility of treated rice straw supplemented with pigeon pea (<i>Cajanus cajan</i>) hay

Chemical composition and in vitro neutral detergent fibre digestibility of treated rice straw supplemented with pigeon pea (<i>Cajanus cajan</i>) hay

Preparation and Characterization of Cellulose Derivatives from Agricultural Wastes

Background: Rice straw was pretreated with dilute alkaline and acid solutions to extract cellulose, which was then converted into cellulose acetate with acetic anhydride and phosphotungstic acid (H3PW12O40·6H2O). The concentration of KOH and the duration of immersion in acetic acid solution affected the removal of hemicellulose and lignin, and after pretreatment with 4% KOH and immersion in acetic acid for 5 hours, the treated rice straw contained 83wt.% cellulose. Phosphotungstic acid has been shown to be an excellent catalyst for the acetylation of rice straw cellulose. The degree of substitution (DS) values had a substantial effect on the solubility of cellulose acetate, and acetone-soluble cellulose acetate with DS values about 2.2 can be generated by varying the amount of phosphotungstic acid and acetylation duration. Objectives: The aim of the study was to evaluate the preparation and characterization of cellulose derivatives from agricultural wastes. Methods: This cross-sectional study was carried out in the Department of Communicable Diseases Control, Director General of Health Services, Dhaka, Bangladesh. For this investigation the rice plant straw was collected from Magura district region. The collected straws were then treated with 3 wt% nitric acid and 1.5 wt% NaOH solution separately. Statistical analyses of the results were be obtained by using window-based Microsoft Excel and Statistical Packages for Social Sciences (SPSS-24). Results: This study observed that the rice straw contained about 35.67% cellulose, 5.50% hemicellulose and 30.18 % α-cellulose. And the wheat straw contained about 43.99% cellulose, 7.30% hemicellulose and 36.70% α-cellulose. The degree of acetylation and degree of substitution of the synthesized cellulose acetate from rice straw were 39.046% and 2.413 respectively. On the other hand, the degree of acetylation and degree of substitution of the synthesized cellulose acetate from wheat straw were 40.79% and 2.59 respectively. ....

Synergistic analysis of lignin degrading bacterial consortium and its application in rice straw fiber film

Fiber film have received widespread attention due to its green friendliness. We can use microorganisms to degrade lignin in straw to obtain cellulose and make fiber films. Herein, a group of high-temperature (50 °C) lignin degrading bacterial consortium (LDH) was enriched and culture conditions for lignin degradation were optimized. Combined with high-throughput sequencing technology, the synergistic effect of LDH-composited bacteria was analyzed. Then LDH was used to treat rice straw for the bio-pulping experiment. The results showed that the lignin of rice straw was degraded 32.4 % by LDH at 50 °C for 10 d, and after the optimization of culture conditions, lignin degradation rate increased by 9.05 % (P < 0.001). The bacteria that compose in LDH can synergistically degrade lignin. Paenibacillus can encode all lignin-degrading enzymes present in the LDH. Preliminary tests of LDH in the pulping industry have been completed. This study is the first to use high temperature lignin degrading bacteria to fabricate fiber film.

The Effects of Monosodium Glutamate by Product Treated Rice Straw in Total Mixed Rations on Rumen Fermentation and Ruminal Microbial Populations Using an In Vitro Gas Technique

The Effects of Monosodium Glutamate by Product Treated Rice Straw in Total Mixed Rations on Rumen Fermentation and Ruminal Microbial Populations Using an In Vitro Gas Technique

Improving Soil Quality and Crop Yields Using Enhancing Sustainable Rice Straw Management Through Microbial Enzyme Treatments.

This study develops a model to raise public awareness about the consequences of burning rice straw after harvest, including environmental pollution, soil degradation, and increased CO2 emissions that contribute to the greenhouse effect. The distinctive feature of the research is the introduction of a post-harvest rice straw treatment process using microbial products capable of secreting cellulase enzymes, which can break down the cellulose in the straw. This process shortens the decomposition time and produces natural organic fertilizer, thus reducing cultivation costs by 60% and increasing crop yields by 20%. The experimental model was carried out in Cam My district, Dong Nai province, Vietnam, including 4 models: no microbial products; using Bio Decomposer; using NTT-01; and using NTT-02. Each experimental field had an area of 650 m². The results showed a significant reduction in straw decomposition time after 14 days of use of the products, with a decomposition rate of up to 80%, nearly twice as fast as without the products. This helps save time, produce natural organic fertilizers, reduce care costs, and increase rice yields, resulting in more income for local residents. These findings demonstrate the effectiveness of microbial treatments in sustainable agriculture and their potential for a broader application in the management of agricultural waste.

Performance improvement of metagenomic laccase immobilized on nanocellulose-reinforced hydrogel nanocomposites for enhanced delignification and detoxification

Immobilization enhances the potential of laccases to degrade lignocellulosic waste, thereby providing an efficient approach for delignification and detoxification. In this study, a comparative analysis of the activity of free and immobilized metagenome-derived laccase (PersiLac2) on nanocellulose (NC)-reinforced hydrogel nanocomposites was performed, and the effectiveness of immobilized laccase in delignification, particularly in relation to rice straw degradation and phenol production, was evaluated. After 1 h of incubation at 90 °C, the immobilized laccase retained 80% of its activity, exhibiting 1.6-fold higher retention than that of the free enzyme. At alkaline pH (8.0–9.0) the free enzyme demonstrated enzymatic activity of 55–65%, while this value was 59–73% for the immobilized form. Immobilization also facilitated easy recovery and reuse of PersiLac2. After 15 cycles, 76.64% of enzyme activity was preserved, highlighting the improved reusability and stability of the immobilized enzyme. Furthermore, leaching tests revealed that the hydrogel-enzyme conjugate maintained a strong connection, with only approximately 20% of the enzyme being leached after 240 min of incubation at 60 °C. This indicates a strong connection between the hydrogel and enzyme structure. Additionally, our study also employed SEM and FTIR analyses, demonstrating the superior performance of immobilized PersiLac2 compared to its free form in the treatment of rice straw. Furthermore, the immobilized enzyme reduced soluble phenols (77.45%) in the slurry of acid-pretreated rice straw. Overall, our findings highlight the potential of immobilizing PersiLac2 on hydrogel nanocomposites to improve enzyme stability, activity, and reusability. This study demonstrates a promising pathway for efficient delignification, phenolic compound removal, and enhanced biomass processing and waste management.

A facile strategy to fabricate lignocellulose-based slow-release fertilizers via a high-performance treatment of rice straw using deep eutectic solvents

Lignin-based slow-release fertilizers (SRFs) have attracted widespread attention due to their ability to enhance nutrient utilization efficiency and reduce environmental pollution in agricultural production. However, the extraction and separation processes of lignin from biomass sources are intricate, involving substantial quantities of non-reusable toxic reagents. Here, a sustainable and eco-friendly approach using deep eutectic solvents (DES) was employed to treat rice straw, effectively dissolving the lignin present. Subsequently, the in-situ lignin regeneration was facilitated through the addition of a zinc chloride solution. The regenerated lignin was tightly wrapped around and connected to cellulose micro/nanofibers, forming a homogeneous slurry. A simple coating technique was employed to uniformly coat urea particles with the lignocellulosic slurry, yielding lignocellulose-based SRFs. Results revealed that the nutrient release of the lignocellulose-based coated fertilizers in water exceeded 56 days. A pot trial demonstrated that the application of lignocellulose-based SRFs significantly promoted the growth of rice and improved grain yield (by 10.7 %) and nitrogen use efficiency (by 34.4 %) compared to the urea treatment in rice production. Furthermore, the DES demonstrated consistently high efficiency in biomass processing even after four cycles of reuse. This green strategy offers a novel approach for the preparation of SRFs coating materials, promoting agricultural sustainability.

Hydrogen chloride treatment of rice straw for upcycling into nanofibrous products for sugar pool

The durability of the harvested wood products is currently contributing to the creation of a temporary carbon pool for the mitigation of global warming. To establish a new method to supply durable fabrication products from grass biomass, a hydrogen chloride treatment process was developed. Applying this treatment to rice straw particles reduced the xylan content and dramatically improved the disintegration efficiency to fibers. The treated and disintegrated particles exhibited a 6.3 times larger specific surface area than the untreated particles, and both particle disassembly into cells and cell surface fibrillation into nanofibrils were observed in microscopy images. The treatment of the particles also improved the susceptibility to enzymatic saccharification, enabling the fiber to be recycled into fermentable sugars after the use as structural materials. Thus, this process offers a method for bioresource management by converting grass into structural materials that pool carbon and sugars.

Molecular structure of dissolved organic carbon in a sandy soil receiving contrasting quality organic residues

Decomposing plant residues release plant-derived dissolved organic carbon (DOC) which can be transformed by microorganisms resulting in microbial-derived DOC (DOC biological function). The adsorbability of DOC to mineral surfaces, determined by DOC chemistry (DOC chemical function), can affect its vertical distribution down soil profiles (D). This study investigated the temporal characteristics (T) and functions (bioavailability, adsorbability) of DOC across the profile of a sandy soil by using chemically contrasting quality (Q) residues: 1) high-cellulose rice straw (RS), 2) nitrogen-rich groundnut stover (GN), 3) lignin-rich dipterocarp leaf litter (DP), and 4) medium-nitrogen and -lignin tamarind leaf litter (TM). Soil samples were collected at two depths (0–15 cm and 60–80 cm) two and eight weeks after residue application, and water-extractable DOC was determined. For the first time, the chemical structure of the extracted DOC was characterized using pyrolysis coupled with mid-infrared spectroscopy (Py-MIRS). The dominant functional groups found in all DOC samples were aromatic, carboxyl, and polysaccharide compounds. The interactive effects of Q, T, and D (soil depth) influenced DOC-polysaccharides, with the most pronounced effect observed in the RS treatment during the early stage, indicating that DOC-polysaccharides were mainly plant-derived. Evidence of partial adsorption of DOC-aromatics and DOC-carboxyls was found in topsoils. These high molecular weight-DOC functional groups may have displaced adsorbed polysaccharides, resulting in higher subsoil DOC-polysaccharides than topsoil, especially under DP and TM. During the later stage, topsoil DOC-polysaccharides were negatively related to microbial metabolic quotient (qCO2) (R2 = 0.938). This relationship led to our hypothesis that the dominant source of DOC-polysaccharides, particularly in the TM treatment, was of microbial origin. A novel discovery from this study is that the chemical quality of plant residues, which serve as the source of DOC, determines the origin of the polysaccharides in DOC. This origin transitioned from plant-derived to microbial-derived as decomposition progressed. Importantly, the presented findings were the first of its kind based on a field experiment.

Effect of acetic acid addition to rice straw pre-treated with urea on performance of dairy ewes.

This experiment was carried out to study the effect of acetic acid addition to rice straws that had been already treated with urea on chemical composition, digestibility, nutritive value, and productive performance of ewes. Thirty ewes with an initial body weight of 44 ± 0.41 kg were chosen 7 days after parturition and divided into 3 groups (10 of each) for 3 months. Each group was assigned randomly to receive one of the three experimental rations composed of concentrate feed mixture and untreated rice straw as a control group (G1), urea-treated rice straw (G2), and urea-acetic acid-treated rice straw (G3). Digestibility coefficients and nutritive value were determined using fifteen mature rams andblood samples were obtained at the end of the collecting period. Findings indicated that the crude protein of rice straw was increased, and crude fiber content was decreased by either urea or urea-acetic acid rations(i.e., G2 and G3). Digestibility of most nutrients was increased (P < 0.05) for animals fed either G2 or G3 rations. There were no significant differences in nutritive value astotal digestible nutrients (TDN) among tested groups; however, digestible crude protein(DCP) increased (P < 0.05) for G2 and G3 rations. Plasma total protein, AST, creatinine, and urea were increased (P < 0.05) by feeding on G2 or G3 ration; however, plasma ALT was not affected. The average daily intake ofdry matter (DM), TDN, and DCP was higher for G2 and G3 rations. Actual milk yield, fat-corrected milk(FCM), percentages of fat, and total solids and constituents yield were increased (P < 0.05) by feeding on treated rice straw rations (i.e.,G2 and G3); however, the percentages of protein, lactose, solids not fat, and ash were not affected. In the 1st month after parturition, the changes in ewes body weight were less (P < 0.05) when they fed on G2 and G3 rations than the control one(G1)). Dams' production and offspring performance were improved (P < 0.05) by feeding on G2 and G3 rations. Feed conversion as kg DMI/kg FCM, kg TDN/kg FCM, and economic efficiency was improved for G2 and G3. Inconcluded, adding acetic acid to urea-treated rice straw may improve the performance of ewes fed on it and increase their milk production and profitability. The same trend was observed with (G2) which received urea-treated rice straw ration.

Effect of Rice Straw Management on Growth Attributes of Potato (Solanum tuberosum L.)

India is the second- largest producer of rice in the world, with 43.86 million hectares of land under rice cultivation where the crop residue generated is more than 160 million tons per year. The rice straw management is a challenging task in rice-producing regions. So, there is a need for an effective waste disposal technology for converting this waste into some valuable form. Keeping this in view,the present investigation was undertaken during the winter (Rabi) season of 2021-22 and 2022-23 at the Research Farm of the KVK Jagdishpur, Sonipat, Department of Vegetable Science, CCS Haryana Agricultural University, Hisar, Haryana to evaluate the effect of rice straw management on the growth attributes of potato.The seed material of potatocv. “KufriKhyati” was grown with twelve different rice straw treatment combinations. The experimental results revealed that the treatment T1 (Removing of straw + Planting) which was at par with treatment T9 (Urea (50kg/ha) + WD (25lt/ha) + FYM (1ton/ha) + Mixing of chopped straw + Planting) performed superiorly over the other treatments with significantly higher values for growth attributes viz., plant emergence (%), plant height (cm), number of stems per hill and number of leaves per hill.

Production of activated carbon granulated by treatment of rice husk and straw with an oil sludge using polyvinyl acetate as a binder

Production of activated carbon granulated by treatment of rice husk and straw with an oil sludge using polyvinyl acetate as a binder

Characterization of lignin and hemicellulose degrading bacteria isolated from cow rumen and forest soil: Unveiling a novel enzymatic model for rice straw deconstruction

Application of greener pretreatment technology using robust ligninolytic bacteria for short duration to deconstruct rice straw and enhance bioethanol production is currently lacking. The objective of this study is to characterize three bacterial strains isolated from the milieux of cow rumen and forest soil and explore their capabilities of breaking down lignocellulose – an essential process in bioethanol production. Using biochemical and genomic analyses these strains were identified as Bacillus sp. HSTU-bmb18, Bacillus sp. HSTU-bmb19, and Citrobacter sp. HSTU-bmb20. Genomic analysis of the strains unveiled validated model hemicellulases, multicopper oxidases, and pectate lyases. These enzymes exhibited interactions with distinct lignocellulose substrates, further affirmed by their stability in molecular dynamic simulations. A comprehensive expression of ligninolytic pathways, including β-ketoadipate, phenyl acetate, and benzoate, was observed within the HSTU-bmb20 genome. The strains secreted approximately 75–82 U/mL of cellulase, xylase, pectinase, and lignin peroxidase. FT-IR analysis of the bacterial treated rice straw fibers revealed that the intensity of lignin-related peaks decreased, while cellulose-related peaks sharpened. The values of crystallinity index for the untreated control and the treated rice straw with either HSTU-bmb18, or HSTU-bmb19, or HSTU-bmb20 were recorded to be 34.48, 28.49, 29.36, 31.75, respectively, which are much higher than that of 13.53 noted for those treated with the bacterial consortium. The ratio of fermentable cellulose in rice straw increased by 1.25-, 1.79-, 1.93- and 2.17-fold following treatments with HSTU-bmb18, HSTU-bmb20, HSTU-bmb19, and a mixed consortium of these three strains, respectively. These aggregative results suggested a novel model for rice straw deconstruction utilizing hydrolytic enzymes of the consortium, revealing superior efficacy compared to individual strains, and advancing cost-effective, affordable, and sustainable green technology.