Degradation Of Straw Research Articles

Rice Straw Degradation with Mixed Cultures of Microfungi and Their Enzymes

Huge quantities of agricultural residues are generated every year but it is neither converted into energy nor allowed to go back to the soil and sometimes burnt that leads to air pollution and loss of soil biology and fertility. Cellulolytic microfungi secrete extracellular enzymes that degrade lignocellulosic biomass in nature and this ability of microbes may be exploited to enhance the rates of degradation of agriculture residues to recycle carbon, nitrogen and minerals in the soil. This study aimed to find out the effect(s) of co-cultivation of high cellulolytic microfungi in various combinations on rice straw under field conditions to enhance its microbial decomposition to discourage the farmers from burning it in the fields. The effectiveness of five fungal cultures in different combinations was tested for efficient degradation of rice straw. Five dominant species of fungi that have been earlier shown to secrete high amounts of cellulases in our own laboratories, were cultured on medium containing yeast powder (2g/L), jaggery (5g/L) and urea (1g/L) at room temperature. Release of reducing sugars from 1 g of rice straw treated with 10IU/mL of fungal extracellular enzymes showed that Penicillium chrysogenum released highest amount of mono and oligomers (96 mg/g) followed by Aspergillus flavus (80 mg/g) and A. oryzae (78 mg/g), A. fumigatus (72 mg/g) and Trichoderma viride (70 mg/g) within 24 h that increased with increasing temperature and increasing period of incubation. Treatment of rice straw with fungal cultures of Penicillium chrysogenum, Aspergillus flavus and A. oryzae revealed that the co-inoculation of all these species decomposed approximately 75% of the total rice straw as assessed by weight loss method. The application extracellular secretory enzymes on rice straw, though, revealed to release of reducing sugars, but the rate of reducing sugars was not sufficient enough to be used for degradation of rice straw under field conditions, hence, the used of mixed cultures of microfungi was planned and tested experimentally, which allowed the decomposition of rice straw much faster than control which were treated with heat-killed dead cultures of test microfungi. Hence, it is recommended that additional spray of mixed cultures of microfungi on rice straw may facilitate its degradation under field conditions.

Microbial Degradation of Plant Residues Rapidly Causes Long-Lasting Hypoxia in Soil upon Irrigation and Affects Leaching of Nitrogen and Metals

With this study, we aim to relate the substrate quality of different organic materials derived from plant residues to the respiratory activity of soil microorganisms after amendment, the formation of oxygen gradients upon irrigation, and the leaching of macronutrients and metals in soil. Elemental analyses were performed to determine the chemical composition of wheat straw, green compost, and a biochar product, showing that carbon availability, C/N ratio, and metal contents varied markedly. Consequently, after application to well-aerated sandy loam soil at 1% w/w, only straw increased microbial activity substantially, and nitrate was depleted within one week. Upon intense irrigation of soil columns packed with differently amended soils, strong hypoxia formed only in straw–soil, where microbial oxygen demand for straw degradation was high. This was enhanced after the application of mineral fertilizers, and nitrate leaching was mitigated. With the decreasing redox potential in straw–soil, the leaching of Fe, Mn, Al, Ni, Co, and As was increased. However, nitrate from mineral fertilizer mitigated the reduction of redox potential and, thus, the leaching of these metals. Measuring oxygen at different depths revealed near anoxic conditions at −15 cm of straw–soil with NP-fertilizer applied within 12 h after the start of irrigation and remained for at least 60 h, while oxygen showed extensive fluctuations in the upper few centimeters. This study showed that organic soil amendments with high carbon availability induce microbial respiration to the extent that causes strong and long-lasting hypoxia upon irrigation, even in sandy soil, which leads to substantial effects on the mobility of nutrients and toxic metals. In contrast, organic soil amendments with low carbon availability did not cause such effects.

Degradation of betaine aldehyde dehydrogenase transgenic maize BZ-136 straw and its effects on soil nutrients and fungal community.

The development of salt-alkali tolerant genetically modified crops represents an important approach to increase grain production in saline-alkali soils. However, there is a paucity of research on the impact of such genetically modified crops on soil microbial diversity. This study aims to investigate the straw degradation of betaine aldehyde dehydrogenase (BADH) transgenic maize BZ-136 and its effects on soil chemical properties, fungal community composition, community diversity and ecological function compared to non-transgenic maize Zheng58 straw. The degradation experiments of BZ-136 straw were carried out under a simulated burying condition with saline-alkali soil for 210 days. The results showed that the degradation rate of C and N of BZ-136 straw was significantly faster than that of Zheng58 in the early stage (p < 0.05). Compared to Zheng58, the straw degradation of BZ-136 increased the soil available nitrogen (AN), total phosphorus (TP), and available phosphorus (AP) in the early stage (p < 0.05). The AN content of soil with BZ-136 straw was 18.16 and 12.86% higher than that of soil with Zheng58 at day 60 and 120 (p < 0.05). The TP content of soil with BZ-136 was higher 20.9 and 20.59% than that with Zheng58 at day 30 and 90 (p < 0.05). The AP content of soil with BZ-136 was 53.44% higher than that with Zheng58 at day 60 (p < 0.05). The straw degradation of BZ-136 increased the OTU number of soil fungal community by 127 (p < 0.05) at day 60, and increased Chao1 and Shannon index at day 60 and 180 (p < 0.05). The degradation rate of C and N in BZ-136 straw was higher than that in Zheng58 at early stage, which led to the phased increase of soil AN and TP contents, and the obvious changes of relative abundances (RA) of some genera and guilds. These findings are important as they provide insight into the potential benefits of BADH transgenic crops in upgrading the soil fertility and the fungal community diversity.

Screening of Cellulose and Pectin Degrading Actinomycetes and Evaluation of the Ability of Composite Flora to Degrade Corn Straw

Corn straw is a type of high-yield agricultural waste in China, but it has not been fully utilized owing to the diffi culty of degrading it and its low utilization rate. To improve the rate of degradation of corn straw and ensure that the straw resources are utilized more fully, we obtained an actinomycete that could simultaneously degrade cellulose and pectin from the cold region and black glebe of northeast China. The strain was named DPA-3-18, and its biological morphology and the sequence of its 16S rRNA were identifi ed. These analyses determined that it is a species of Streptomyces. The strain was combined with the lab-stored GS-30 and Bacillus subtilis to construct composite fl ora and conduct a single factor experiment. Signifi cantly higher factors were selected by Plackett Burman, and its fermentation conditions were optimized using response surface methodology. The optimal cultivation conditions were 4% of inoculum, a culture temperature of 28.51°C, an initial pH value of the medium of 7.43, and the oscillation during fermentation took place at 199.62 rpm. Under these conditions, 40.38% of the corn straw was degraded. F rom the results of SEM, we found that the structure of corn straw before degradation was complete, and the internal structure of corn straw after degradation with c omposite fl ora was destructed. The FT-IR spectra shown that the absorption peaks in all places of corn straw were reduced after degradation by the composite fl ora, the absorption peaks at 1640 cm-1 of corn straw after degradation were lower than that of before degrad ation, which confi rmed the decrease in cellulose. It indicated that the corn straw was signifi cantly degraded by the composite fl ora. This study contributed to understanding the change in corn straw after fermentation by the composite fl ora, and providing a theoretical basis for comprehensive utilization of corn straw.

Expansion combined with Irpex lacteus fungal treatment for enhancing buckwheat straw degradation

Pretreatment is an essential step in the industrial application of lignocellulosic biomass. To improve the conversion efficiency of lignocellulose while shortening the modification time of biological treatments, white rot fungus (Irpex lacteus) combined with expansion has been proposed as an effective degradation strategy for buckwheat straw. The mechanism of the combined pretreatments was evaluated in terms of chemical composition, enzyme production, crystallinity, and chemical bonds. In vitro ruminal gas production was measured after 96 h of incubation using an automatic system. The results showed that expansion promoted mycelium growth and increased the neutral detergent solute content. Moreover, expansion enhanced selective degradation by increasing laccase activity and prolonging the duration of laccase and manganese peroxidase activity, thereby increasing the degradation rate of lignin from 33% in 28 days to 31% in 14 days or 44% in 21 days. Expansion significantly reduced the crystallinity and broke the chemical bonds, thereby reducing the structural resistance to the fungal treatment. Expansion creates favorable conditions for I. lacteus modification, which significantly enhanced lignocellulose degradation and in vitro rumen gas production. The combined treatment reduced the treatment time and improved the production efficiency.

Laccase-Based Self-Amplifying Catalytic System Enables Efficient Antibiotic Degradation for Sustainable Environmental Remediation.

Antibiotic contamination poses potential risks to ecosystems and human health. Laccase (LAC) has emerged as a promising biocatalyst for the oxidation of environmentally toxic contaminants with high catalytic efficiency; however, its large-scale application is hindered by enzyme costs and dependency on redox mediators. Herein, a novel self-amplifying catalytic system (SACS) for antibiotic remediation that does not require external mediators is developed. In SACS, a natural mediator-regenerating koji with high-activity LAC, derived from lignocellulosic waste, initiates the chlortetracycline (CTC) degradation. Subsequently, an intermediate product, CTC327, identified as an active mediator for LAC via molecular docking, is formed and then starts a renewable reaction cycle, including CTC327-LAC interaction, stimulated CTC bioconversion, and self-amplifying CTC327 release, thus enabling highly efficient antibiotic bioremediation. In addition, SACS exhibits excellent performance in producing lignocellulose-degrading enzymes, highlighting its potential for lignocellulosic biomass deconstruction. To demonstrate its effectiveness and accessibility in the natural environment, SACS is used to catalyze in situ soil bioremediation and straw degradation. The resulting CTC degradation rate is 93.43%, with a straw mass loss of up to 58.35% in a coupled process. This mediator regeneration and waste-to-resource conversion in SACS provides a promising route for environmental remediation and sustainable agricultural practices.

In vitro ruminal degradability of wheat straw cultivated with white-rot fungi adapted to mushroom farming conditions

Biological treatment of cereal straw for ruminant nutrition purposes might present an environmentally friendly option of valorizing a widely available by-product of grain production for farming systems with low external input. Several strains of white-rot fungi have been selected in the past under mostly controlled laboratory conditions for their capacity of lignin degradation. The study adapted to conditions on farm for upscaling purposes. The development of the in vitro straw digestibility with two different moistening pre-treatments and inoculated with three different fungi species, namely Pleurotus ostreatus, Ceriporiopsis subvermispora and Volvariella volvacea, was determined up to 42 days of fermentation with five sampling times. The effect of physical straw pre-treatments on nutritional parameters was evaluated. The neutral detergent fiber digestibility (NDFD30h), enzymatically soluble organic substance (ELOS) and the gas production (Hohenheim Feed value Test, HFT) as indicators for in vitro ruminal degradability decreased over time independent of the fungus: HFT, ELOS and NDFD30h by up to 50, 35 and 30% of the original straw. Remoistening and autoclaving the straw increased the gas production significantly by 2.6 mL/200 g dry matter (DM), and ELOS and NDFD30h by 45 and 51 g/kg DM compared to the original straw (34.9 mL/200 mg DM, 342 g/kg DM, 313 g/kg NDF).

The effects of adding exogenous lignocellulose degrading bacteria during straw incorporation in cold regions on degradation characteristics and soil indigenous bacteria communities.

Low temperature is one of the bottleneck factors that limits the degradation of straw during rice straw incorporation. Determining strategies to promote the efficient degradation of straw in cold regions has become a highly active research area. This study was to investigate the effect of rice straw incorporation by adding exogenous lignocellulose decomposition microbial consortiums at different soil depths in cold regions. The results showed that the lignocellulose was degraded the most efficiently during straw incorporation, which was in deep soil with the full addition of a high-temperature bacterial system. The composite bacterial systems changed the indigenous soil microbial community structure and diminished the effect of straw incorporation on soil pH, it also significantly increased rice yield and effectively enhanced the functional abundance of soil microorganisms. The predominant bacteria SJA-15, Gemmatimonadaceae, and Bradyrhizobium promoted straw degradation. The concentration of bacterial system and the depth of soil had significantly positive correlations on lignocellulose degradation. These results provide new insights and a theoretical basis for the changes in the soil microbial community and the application of lignocellulose-degrading composite microbial systems with straw incorporation in cold regions.

Dynamic variation of bacterial community assemblage and functional profiles during rice straw degradation.

Bacteria is one of the most important drivers of straw degradation. However, the changes in bacterial community assemblage and straw-decomposing profiles during straw decomposition are not well understood. Based on cultivation-dependent and independent technologies, this study revealed that the "common species" greatly contributed to the dynamic variation of bacterial community during straw decomposition. Twenty-three functional strains involved in straw decomposition were isolated, but only seven were detected in the high-throughput sequencing data. The straw decomposers, including the isolated strains and the agents determined by functional prediction, constituted only 0.024% (on average) of the total bacterial community. The ecological network showed that most of the identified decomposers were self-existent without associations with other species. These results showed that during straw composition, community assembly might be greatly determined by the majority, but straw decomposition functions might be largely determined by the minority and emphasized the importance of the rare species in community-specific functions.

Effects of rumen microorganisms on the decomposition of recycled straw residue.

Recently, returning straw to the fields has been proved as a direct and effective method to tackle soil nutrient loss and agricultural pollution. Meanwhile, the slow decomposition of straw may harm the growth of the next crop. This study aimed to determine the effects of rumen microorganisms (RMs) on straw decomposition, bacterial microbial community structure, soil properties, and soil enzyme activity. The results showed that RMs significantly enhanced the degradation rate of straw in the soil, reaching 39.52%, which was 41.37% higher than that of the control on the 30th day after straw return. After 30 d, straw degradation showed a significant slower trend in both the control and the experimental groups. According to the soil physicochemical parameters, the application of rumen fluid expedited soil matter transformation and nutrient buildup, and increased the urease, sucrase, and cellulase activity by 10%‒20%. The qualitative analysis of straw showed that the hydroxyl functional group structure of cellulose in straw was greatly damaged after the application of rumen fluid. The analysis of soil microbial community structure revealed that the addition of rumen fluid led to the proliferation of Actinobacteria with strong cellulose degradation ability, which was the main reason for the accelerated straw decomposition. Our study highlights that returning rice straw to the fields with rumen fluid inoculation can be used as an effective measure to enhance the biological value of recycled rice straw, proposing a viable solution to the problem of sluggish straw decomposition.

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.

Effects of Different Soil Moisture Contents on Rumen Fluids in Promoting Straw Decomposition after Straw Returning

Inoculating microbial inoculants to speed up the decomposition of returning straw is currently a hot topic. Meanwhile, the soil moisture content (SMC) could change the diversity, abundance, and metabolism of the soil microbial community structure, which affects the straw degradation rate under the straw returning condition. In this research, rumen microorganisms with strong decomposing abilities in natural systems were used as inoculants to promote straw decomposing and returning to the field. The effects of the SMC on straw decomposition under rumen fluid (RF)-induced returning were investigated. Experiments were conducted for 30 days with typical paddy soil in the south of China under conditions of 30%, 70%, and 100% SMC. With an increase in the SMC within a certain range (30~100%), the decomposition rate of straw showed a trend of first rising and then falling. Treatments of 70% SMC with RF addition generally achieved the maximum rate of straw degradation. The peak value was 49.96%, which was 2.67-fold higher than the treatments of 30% SMC with RF addition (18.74%) and 24.1% higher than those of the control with 70% SMC (40.3%) (p &lt; 0.05). Moreover, a straw structural analysis proved that at 70% SMC, microorganisms from RF favored the destruction of functional groups on the straw surface and the degradation of cellulose. Meanwhile, it was shown that RF could promote the decay of straw, leading to increments in enzyme activities and soil nutrients. The higher the soil moisture content, the higher the key soil enzyme activities. This indicates that the diversity and abundance of cellulose-degrading bacteria and fungi in soil microorganisms and rumen microorganisms were changed with different soil moisture contents. The experimental findings suggest an innovative way to further utilize rumen microorganisms.

Arbuscular Mycorrhizal Fungi Promote the Degradation of the Fore-Rotating Crop (Brassica napus L.) Straw, Improve the Growth of and Reduce the Cadmium and Lead Content in the Subsequent Maize

Arbuscular mycorrhizal fungi (AMF) are widely present in heavy metal-polluted soils, but their effects on straw degradation and plant growth of rotated crops are poorly understood. In this study, a pot experiment was used to simulate the return of fore-rotating crop (Brassica napus L.) straw to farmland with a subsequent planting of maize in a lead–zinc mining area on the Yunnan Plateau, Southwest China, which included four treatments: control (CK), addition of rape straw (SR), inoculation of AMF (AMF), and both AMF inoculation and straw addition (AMF + SR). The effects of AMF on the degradation and nutrient release of the fore-rotating rape straw and the growth, mineral nutrition and the cadmium (Cd) and lead (Pb) contents of the subsequent maize were investigated. Compared with the CK treatment, AMF significantly promoted the degradation of rape straw and the release of mineral nutrients (nitrogen, phosphorus and potassium) as well as the Cd and Pb, increased the content of available nutrients in soil, and improved the mineral nutrient contents in the maize. AMF + SR significantly increased the maize height and biomass by 32–35% and decreased the available Cd and Pb contents in soil and the Cd and Pb contents in the maize by 20–30% and 18–25%, respectively. Moreover, the available Cd and Pb contents in the soil presented significant positive correlations with their contents in the maize but negative correlations with the height and biomass of the maize. Thus, AMF played an important regulatory role in the nutrient cycling and heavy metal accumulation of the crop rotation.

Thermal degradation behaviour and chemical kinetic characteristics of biomass pyrolysis using TG/DTG/DTA techniques

The goal of the current study is to investigate the thermal degradation of palm fronds (PF), olive leaves (OL), and wheat straw (WS) through pyrolysis and calculate their kinetic data using TG-DTG and DTA approaches. The kinetic parameters were assessed using isoconversional techniques like the Ozawa-Flynn-Wall (OFW) and Kissinger–Akahira–Sunose (KAS) methods, as well as model-fitting techniques like the integral method, which employs various diffusion and reaction order models. Using kinetics data models, typical parameters for pyrolysis and thermodynamics were estimated. For PF, OL, and WS, the values of activation energy (E) from the integral method ranged between 8.82 and 167.13, 23.06 and 149.20, and 11.01 and 156.27, respectively, for diffusion models. On the other hand, the values of (E) ranged between 22.3 and 117.49, 51.69 and 92.88, and 23.48 and 125.97, respectively, for reaction-order models. The average activation energies (E) calculated by using PF, OL, and WS samples are 91.9, 69.1, and 65.2, respectively, for the OFW method and 87.5, 101.8, and 63.4, respectively, for the KAS method. The results demonstrated that the integral method provided values of (E) that were almost identical to those produced by the KAS and OFW methods. In the same range of (α), results showed that reaction order models yielded greater frequency factor values than diffusion models, demonstrating how simpler and quicker pyrolysis is. The values of (ΔGav\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\Delta \\mathrm{G}}_{av}$$\\end{document}) demonstrated the acceptability of these materials for pyrolysis, and for the OFW and KAS techniques, the sequence of the degradation process was OL > WS > PF. The calculated (ΔGav\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\Delta \\mathrm{G}}_{av}$$\\end{document}) showed that more heat energies are required for OL, PF, and WS to dissociate the reagent bonds, which agrees with the (E) values derived from the OFW model.Graphical

Trade-off between microbial ecophysiological features regulated by soil fertility governs plant residue decomposition

Soil fertility influences microbial-driven plant residue decomposition, thus further affecting soil organic carbon (C) formation. Both ecological and physiological features of microbial communities change with soil fertilities, however, the mechanism of how soil fertility influences microbial ecophysiological features (both the taxonomic and functional profiles) driving plant residue decomposition is unclear. Here, four series of microcosms were set up, inoculated with two distinct soils, each with low and high fertility levels as a result of contrasting long-term fertilization regimes, and incubated with 13C-labeled rice straw amendments. DNA stable-isotope probing (DNA-SIP) based amplicon sequencing and shotgun metagenomic sequencing were conducted. We found that both bacterial community composition (including the relative abundance, α- and β-diversities, and taxonomic composition) and carbohydrate metabolic efficiency were significantly changed under different soil fertilities. High fertile soils gave rise to greater increases in bacterial populations and straw decomposition than low fertile soils, yet DNA-SIP-based shotgun metagenomic sequencing showed that the bacterial average carbohydrate metabolic efficiency, characterized by the average carbohydrate-active enzyme (CAZyme) abundance within each bacterial phylum was significantly lower. Linear regressions between bacterial ribosomal RNA operon (rrn) copy number and bacterial carbohydrate metabolic efficiency under contrasting soil fertilities suggested that high fertile soils select for fast-but-inefficient bacteria to degrade rice straw while low fertile soils select for slow-but-efficient ones. Collectively, the data demonstrate a fundamental trade-off between the ecological and physiological attributes of straw-degrading microbial communities. The trade-off is regulated by soil fertility and in turn governs plant residue decomposition. This work provides novel insights for better understanding the ecological and physiological roles of microbes in organic matter decomposition and global terrestrial C cycling, especially in the context of crop straw degradation under contrasting soil fertilities.

Exogenous microbial antagonism affects the bioaugmentation of humus formation under different inoculation using Trichoderma reesei and Phanerochaete chrysosporium

This study was aimed at exploring the effect of antagonism of Trichoderma reesei (T.r) and Phanerochaete chrysosporium (P.c) on humification during fermentation of rice (RS) and canola straw (CS). Results showed that exogeneous fungi accelerated straw degradation and enzyme activities of CMCase, xylanase and LiP. P.c inhibited the activity of LiP when co-existing with T.r beginning, it promoted the degradation of lignin and further increased the production of humus-like substances (HLS) and humic-like acid (HLA) in later fermentation when nutrients were insufficient. The HLS of RTP was 54.9 g/kg RS, higher than the other treatments, and displayed more complex structure and higher thermostability. Brucella and Bacillus were the main HLA bacterial producers. P.c was the HLA fungal producer, while T.r assisted FLA and polyphenol transformation. Therefore, RTP was recommended to advance technologies converting crop straw into humus resources.

Forming and Degradation Mechanism of Bowl Seedling Tray Based on Straw Lignin Conversion

In response to the problems of low straw utilization efficiency and poor returning effect in Northeast China, this paper takes rice straw containing cow dung as the experimental material, and according to the characteristics of lignin glass transformation of the material, proposes a new method to prepare biomass seedling trays. The seedling trays prepared by this method can meet the needs of corn seedling cultivation and transplantation. To study the molding mechanism, scanning electron microscopy and a universal testing machine were used to compare the changes in the internal structure and mechanical properties of the regularly- and hot-compressed seedling trays before and after seedling raising. The results show that the material with water content of 23% has the best hot-pressing effect. The forming mechanism is: that the strength of the molded seedling tray resulted from the mechanical setting force of the multilayered stem fibers with a mosaic structure within the seedling tray. The adhesion and wrapping by lignin prevented water penetration from damaging the multilayered stem fibers and slightly improved their strength. The seedling tray made of straw and manure was completely degraded over 40 days, and the straw degradation rate was improved. This method can increase the overall quality and benefits of straw, providing a foundational reference for high-quality and high-efficiency straw utilization.

Screening of Dominant Cellulose-Degrading Microbe in Humus and Optimisation of its Enzyme Producing Conditions and Application Optimization of Enzyme Production Conditions and Evaluation of Efficient Straw Degradation by Penicillium oxalicum

Screening of Dominant Cellulose-Degrading Microbe in Humus and Optimisation of its Enzyme Producing Conditions and Application Optimization of Enzyme Production Conditions and Evaluation of Efficient Straw Degradation by <i>Penicillium oxalicum</i>

Screening and isolation of cold-adapted cellulose degrading bacterium: A candidate for straw degradation and De novo genome sequencing analysis.

Degradation of crop straw in natural environment has been a bottleneck. There has been a recent increase in the exploration of cold-adapted microorganisms as they can solve the problem of corn straw degradation under low temperatures and offer new alternatives for the sustainable development of agriculture. The study was conducted in low-temperature (10°C) and high-efficiency cellulose-degrading bacteria were screened using carboxymethyl cellulose (CMC) selection medium and subjected to genome sequencing by the third-generation Pacbio Sequl and the second-generation Illumina Novaseq platform, and their cellulase activity was detected by 3,5-dinitrosalicylic acid (DNS) method. The results showed that the low-temperature (10°C) and high-efficiency cellulose-degrading bacterium Bacillus subtilis K1 was 4,060,823 bp in genome size, containing 4,213 genes, with 3,665, 3,656, 2,755, 3,240, 1,261, 3,336 and 4,003 genes annotated in the non-redundant protein sequence database (NR), Pfam, clusters of orthologous groups of proteins (COGs), Genome Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and Annotation databases, respectively. In addition, a large number of lignocellulose degradation-related genes were annotated in the genome. The cellulose activity of B. subtilis K1 was higher, exhibiting the highest activity of endo-β-glucanase (24.69 U/ml), exo-β-glucanase (1.72 U/ml) and β-glucosaccharase (1.14 U/ml). It was found that through adding cold-adapted cellulose-degrading bacteriaK1 in the corn straw composting under 6°C (ambient temperature), the average temperature of straw composting was 58.7°C, and higher 86.7% as compared to control. The HA/FA was higher 94.02% than the control and the lignocellulose degradation rate was lower 18.01-41.39% than the control. The results provide a theoretical basis for clarifying the degradation potential of cold-adapted cellulose-degrading bacteria and improving the cellulose degradation efficiency.

Efficient Removal of Heavy Metals from Contaminated Sunflower Straw by an Acid-Assisted Hydrothermal Process.

The removal of heavy metals is crucial to the utilization of contaminated biomass resources. In this study, we report an efficient process of hydrothermal conversion (HTC) of sunflower straw (Helianthus annuus L.) to remove heavy metals. The effect of different HTC temperatures and concentrations of HCl additives on heavy metal removal efficiency was investigated. The results revealed that increasing the temperature or concentration of HCl promoted the transfer of heavy metals from hydrochar to liquid products during HTC. The heavy metals removed to the liquid products included up to 99% of Zn and Cd, 94% of Cu, and 87% of Pb after hydrothermal conversion with a temperature of 200 °C and HCl 2%. The species of heavy metals in hydrochars converted from unstable to stable with an increase in temperature from 160 °C to 280 °C. The stable fractions of heavy metals in the acidic condition decreased as the acid concentration increased. This aligns well with the high transfer efficiency of heavy metals from the solid phase to the liquid phase under acidic conditions. The FTIR indicated that the carboxy and hydroxy groups decreased significantly as the temperature increased and the concentration of HCl increased, which promoted the degradation of sunflower straw. A scan electron microscope showed that the deepening of the destruction of the initial microstructure promotes the transfer of heavy metals from hydrochars to liquid phase products. This acid-assisted hydrothermal process is an efficient method to treat biomass containing heavy metals.