Cellulose Degradation Research Articles

Warming-induced response of microbial diversity and functions regulated microbial necromass and soil multifunctionality

Microbial necromass has been proved to be an important source of stable soil organic carbon (SOC), responding sensitively to global climate warming. Nevertheless, how the response of the soil microbial community to warming influences microbial necromass and ecosystem multifunctionality remains unclear. Here, amino sugars (ASs) were investigated as biomarkers of microbial necromass to evaluate bacterial and fungal necromass in a 60-day indoor warming incubation experiment, as well as the contribution of bacterial and fungal necromass to SOC. And amplicon sequencing and a high-throughput qPCR-based chip were integrated the changes in soil microbial community composition of whole, abundant, and rare taxa, as well as microbial traits (diversity, functional genes). The results showed that warming altered soil microbial community compositions, especially fungi. Under warming, bacterial necromass C and its contribution to SOC increased, while vice versa for fungi. The changes in microbial necromass C were closely associated with increasing C degradation gene abundance, such as cellulose, hemicellulose, and chitin degradation genes. Warming slightly increased soil ecosystem multifunctionality in relation to soil carbon cycling, associated with soil microbial diversity. Rare taxa diversity broadly promoted most single functions and multifunctionality. The impacts of different microbial taxa diversity on multifunctionality were broadly following the order: fungi > bacteria, abundant taxa > whole taxa > rare taxa. Simultaneously accounting for the effects of warming on multiple biotic and abiotic factors, multifunctionality and the contribution of microbial necromass to SOC were driven by nitrogen content, pH, soil microbial biomass, and diversity. Therefore, this study emphasized the crucial roles of microbial diversity, and microbial functions in regulating soil organic carbon pools and soil carbon cycling functions under global climate warming.

Deciphering the driving mechanism of microbial community for rapid stabilization and lignocellulose degradation during waste semi-aerobic bioreactor landfilling with multifunctional microbial inoculum.

Owing to the massive refractory lignocellulose and leachate-organic loads, the stabilization of municipal solid waste (MSW) landfill is often prolonged, resulting in environmental burdens. Herein, various assembled multifunctional microbial inoculums (MMIs) were introduced into the semi-aerobic bioreactor landfill (SABL) to investigate the bioaugmentation impacts. Compared to control (CK) and other MMIs treatments (G1-G3), LD+LT+DM inoculation (G4) significantly increased volatile solids degradation (9.72-45.03%), while reducing chemical oxygen demand (COD) content (10.34-51.85%) and ammonia nitrogen concentration (80.71-90.95%) in the leachate. G4 also exhibited significantly higher degradation of cellulose and hemicellulose, achieving 0.99 and 1.94 times higher efficiency than CK, respectively. Microbial analysis revealed that LD+LT+DM reshaped microbial communities composition of SABL, with most of the introduced microorganisms (Enterobacter, Sphingobacterium, Streptomyces, etc.) successfully colonizing, and stimulating indigenous functional microbes associated with organic matter decomposition. Additionally, microbial interactions were strengthened in G4, accompanied by the higher abundance of 11 biomarkers and enzymes involved in lignocellulose degradation and ammonia nitrogen conversion. Overall, LD+LT+DM maximized MMI function by reconstructing synergistic core microbes. These findings highlight the superiority of LD+LT+DM in simultaneously regulating the microbial composition of lignocellulose-rich waste landfills, expediting MSW decomposition, improving leachate treatment, and mitigating odor emissions, offering valuable insights for efficient MSW management.

Genome-based analysis reveals niche differentiation among Firmicutes in full-scale anaerobic digestion systems.

Fermentative Firmicutes species are key players in anaerobic digestion; however, their niche differentiation based on carbohydrate utilization in full-scale systems remains unclear. In this study, we investigated niche differentiation among four major Firmicutes classes using a genome-centric approach, reconstructing 39 high-quality metagenome-assembled genomes. Limnochordia and Clostridia exhibited the broadest substrate versatility, utilizing 24% and 18% of the predicted substrates, respectively. Although common substrates were shared, each class demonstrated unique substrate preferences driven by distinct functional and metabolic differences. Limnochordia and Clostridia possess unique carbohydrate-active enzyme families, such as GH177 and CBM91, which enable xylan and arabinan degradation. Bacilli were abundant with the GH1 and GH3 families, which are critical for cellulose degradation. Overall, the Firmicutes classes showed low overlap in substrate use and functional profiles, confirming significant niche differentiation. Our results demonstrate that Firmicutes occupy distinct dietary niches supporting insights into bacterial coexistence in anaerobic digestion systems.

Interactions between gut microbes and host promote degradation of various fiber components in Meishan pigs.

Studies on porcine intestinal microbiota have been widely conducted, and some microbial taxa with fiber degradation functions have been identified. However, the mechanisms of division among gut microbes in the degradation of complex fiber components are still unclear. In addition, the regulation of fiber digestion by host through absorption of short-chain fatty acids (SCFAs) needs to be further investigated. Our study used apparent total tract digestibility of dietary fiber to assess the utilization efficiency of dietary fiber between Meishan and Large White pigs. Subsequently, through metagenome sequencing and determination of fiber-degrading products, we found that in Meishan pigs, positive interactions among Treponema bryantii, Treponema sp., Rikenellaceae bacterium, and Bacteroidales bacterium WCE2004 facilitated the degradation of both cellulose and pectin. RNA-seq analysis elucidated breed-specific genes associated with SCFA absorption in cecum. By integrating multi-omics data, we constructed a framework outlining host-microbiota interactions that control dietary fiber utilization in pigs. Our data provide novel insights into host-microbiota interactions regulating fiber degradation and lay some theoretical foundations for improving the utilization efficiency of high-fiber cereal feed in pigs through targeted modulation of gut microbial function.

Variations in carbohydrates molar mass distribution during chemical degradation and consequences on fibre strength

Abstract Industrial oxygen-delignified and fully-bleached hardwood kraft pulps were treated with chemicals to provoke carbohydrates depolymerisation: ozone, hypochlorous acid, and cellulase. The degrees of polymerisation (DP) of cellulose obtained by pulp viscosity measurement in Cuen and by size-exclusion chromatography after direct dissolution in DMAc/LiCl indicated the extent of the chemical degradation inflicted to the fibres. Molar mass distributions (MMD) described the carbohydrates depolymerisation patterns. Fibre strength was assessed by measuring the zero-span tensile index at never-dried state. Fibre strength deterioration seemed to be mainly driven by the topochemistry of the cellulose degradation (homogeneous or localised), rather than by its intensity usually measured as an average DP loss. In fact, depolymerisation by cellulase was found critically detrimental to fibres strength whereas ozone and hypochlorous acid induced little harm to the fibres despite a significant cellulose depolymerisation. According to these results, in line with several past studies, fibre strength measurements should be performed systematically as the sole pulp viscosity is an inadequate indicator. Alternatively, albeit being insufficient strength predictors on their own MMD can give valuable insight on the topochemistry of the cellulose degradation, a key aspect when monitoring fibre strength preservation during pulping and bleaching.

Seed microbiomes promote Astragalus mongholicus seed germination through pathogen suppression and cellulose degradation

BackgroundSeed-associated microorganisms play crucial roles in maintaining plant health by providing nutrients and resistance to biotic and abiotic stresses. However, their functions in seed germination and disease resistance remain poorly understood. In this study, we investigated the microbial community assembly features and functional profiles of the spermosphere and endosphere microbiomes related to germinated and ungerminated seeds of Astragalus mongholicus by using amplicon and shotgun metagenome sequencing techniques. Additionally, we aimed to elucidate the relationship between beneficial microorganisms and seed germination through both in vitro and in vivo pot experiments.ResultsOur findings revealed that germination significantly enhances the diversity of microbial communities associated with seeds. This increase in diversity is driven through environmental ecological niche differentiation, leading to the enrichment of potentially beneficial probiotic bacteria such as Pseudomonas and Pantoea. Conversely, Fusarium was consistently enriched in ungerminated seeds. The co-occurrence network patterns revealed that the microbial communities within germinated and ungerminated seeds presented distinct structures. Notably, germinated seeds exhibit more complex and interconnected networks, particularly for bacterial communities and their interactions with fungi. Metagenome analysis showed that germinated seed spermosphere soil had more functions related to pathogen inhibition and cellulose degradation. Through a combination of culture-dependent and germination experiments, we identified Fusarium solani as the pathogen. Consistent with the metagenome analysis, germination experiments further demonstrated that bacteria associated with pathogen inhibition and cellulose degradation could promote seed germination and vigor. Specifically, Paenibacillus sp. significantly enhanced A. mongholicus seed germination and plant growth.ConclusionsOur study revealed the dynamics of seed-associated microorganisms during seed germination and confirmed their ecological role in promoting A. mongholicus seed germination by suppressing pathogens and degrading cellulose. This study offers a mechanistic understanding of how seed microorganisms facilitate successful seed germination, highlighting the potential for leveraging these microbial communities to increase plant health.9Vhf17h9wMs7kvS_yZTv5-Video

Cellulase from Halomonas elongata for biofuel application: enzymatic characterization and inhibition tolerance investigation

Halophilic bacteria are promising candidates for biofuel production because of their efficient cellulose degradation. Their cellulases exhibit high activity, even in the presence of inhibitors and under extreme conditions, making them ideal for biorefinery applications. In this study, we isolated a strain of Halomonas elongata (Kadal6) from decomposed cotton cloth on a Rameshwaram seashore. Morphological, biochemical, and 16S rRNA analyses revealed that Kadal6 was 99.93% similar to the cellulase-producing strain, H. elongata MH25661. The tolerance of the cellulase to inhibitors was assessed through molecular docking with a cellulase model of MH25661 generated by I-TASSER and experimentally using response surface methodology (RSM) with Kadal6. A molecular docking study indicated a high inhibition constant for ethanol, hydroxymethylfurfural (HMF), and furfural. Cellulase from H. elongata Kadal6 (CellHe) showed a maximum inhibition rate of 44.27% at 55 °C, 15% ethanol, and 6.5 g/L furfural and HMF. The enzyme retained 50% of its activity in the presence of these inhibitors, and remained unaffected at 1 g/L furfural and HMF, although inhibition occurred at 3 g/L. H. elongata cellulase demonstrated significant tolerance to inhibition both in vitro (RSM) and in silico, indicating its potential for biorefinery applications in harsh environments.

Enhancing cellulose and hemicellulose degradation in wheat straw composting by inoculation with Glycomyces: key factors and microbial community dynamics

ABSTRACT Actinobacteria are widely used in aerobic composting of straw waste because of their good degradation effect on lignocellulose. However, there are few studies on the degradation effect of Glycomyces on straw. In this study, six laboratory-scale treatments were conducted: corn straw composting with Glycomyces inoculation (CSI), rice straw composting with Glycomyces inoculation (RSI), and wheat straw composting with Glycomyces inoculation (WSI). Additionally, composting control groups were set up for each type of straw without inoculation: corn straw (CS), rice straw (RS), and wheat straw (WS). Subsequently, a series of chemical analyses and enzymological methods were used to assess the effects of Glycomyces inoculation on environmental variables, enzyme activities, and organic components. Also, high-throughput sequencing was employed to explore the microbial community composition that greatly contributed to the degradation rate of cellulose and hemicellulose during the degradation process of wheat straw. Finally, the factors influencing the cellulose and hemicellulose degradation in WSI were identified using structural equation models (SEMs). The results showed that cellulose and hemicellulose degradation rates were higher in the Glycomyces-inoculated treatment groups than in the non-inoculated groups. Importantly, the degradation rates of cellulose and hemicellulose in WSI were the highest, at 68.09% and 66.81%, respectively. Collectively, total nitrogen and the microbial community structure of the top 30 genera contributing to cellulose and hemicellulose degradation were important factors influencing the straw degradation of WSI. This study not only provides new insights into the regulation of wheat straw degradation, but also has great significance for environmental protection.

Advancing Energy Recovery: Evaluating Torrefaction Temperature Effects on Food Waste Properties from Fruit and Vegetable Processing

Most organic waste from food production is still not used for energy production. From the perspective of energy production, one option is to valorise the properties of organic waste. The fruit juice industry is growing rapidly and generates large amounts of waste. One of the main wastes in food and fruit juice processing is peach pits and apple peels. The aim of this study was to analyse the influence of torrefaction temperature on the properties of food waste, namely apple peels, peach pits and pea shells, in order to improve their energy value and determine their potential for further use and valorisation as a renewable energy source. The aim was to analyse the influence of different torrefaction temperatures on the heating value (HHV), mass yield (MY) and energy yield (EY) in order to better understand the behavior of the thermal properties of individual selected samples. The torrefaction process was carried out at temperatures of 250 °C, 350 °C and 450 °C. The obtained biomass was compared with dried biomass. For apple peels, HHV after torrefaction was (28 kJ/kg), MY decreased by (66–34%), while EY fell by (97–83%). Peach pits, despite a higher HHV after torrefaction (18 kJ/kg), achieved low MY (38–89%) and EY (59–99%), which reduces their efficiency in biochar production. Pea peels had EY (82–97%) and a lower HHV after torrefaction (11 kJ/kg), but their high ash content limits their wider use. The results confirm that, with increasing temperature, MY and EY for all selected biomasses decrease, which is a consequence of the degradation of hemicellulose and cellulose and the loss of volatile compounds. In most cases, increasing the torrefaction temperature improved the resistance to moisture adsorption, as this is related to the thermal process that causes structural changes. The results showed that the torrefaction process improved the hydrophobic properties of the biomass samples. Temperature was seen to have a great impact on mass energy efficiency. Apple peels generally had the highest mass and energy yield.

Site-Specific Hydrogeological Characterization for Radiological Safety: Integrating Groundwater Dynamics and Transport

The radiological impact of radionuclide transport via groundwater pathways at the Wolsong Low- and Intermediate-Level Waste (LILW) Disposal Center was estimated by considering site-specific characteristics, including hydrogeology, geochemistry, and land use. Human intrusion scenarios, such as groundwater well development, were analyzed to evaluate potential pumping volumes and radionuclide migration pathways. Particular attention was given to the hydrological and geochemical aspects of radionuclide transport, with a focus on local aquifer heterogeneity, flow dynamics, and interactions with engineered barriers and surrounding rock formations that delay radionuclide migration through sorption and other retention mechanisms. Sorption coefficients (Kd), calibrated using site-specific geochemical data, were incorporated to ensure realistic modeling of radionuclide behavior. A hierarchical approach integrating scenario screening, particle tracking techniques, and mass transfer modeling was employed. Numerical simulations using FEFLOW ver. 7.3 and GoldSim ver. 14.0 software provided insights into near-field and far-field transport phenomena under well pumping conditions. The results revealed distinct spatial flux behaviors, where carbon-14 (14C) dominated near-field flux due to its high inventory, while technetium-99 (99Tc) emerged as the primary dose contributor in the far-field flux, owing to its anionic nature and limited sorption capacity. Additionally, under high-pH conditions near concrete barriers, cellulose degradation into isosaccharinic acid was identified, enhancing radionuclide mobility through complex formation. These findings underscore the importance of site-specific sorption and speciation parameters in safety assessment and highlight the need for accurate geochemical modeling to optimize waste placement and ensure long-term disposal safety. The outcomes provide valuable insights for optimizing waste placement and contribute to the development of evidence-based safety strategies for long-term performance assessment.

Heat Tolerance Differences Between Hu Sheep and Hu Crossbred Sheep in Microbial Community Structure and Metabolism.

The frequent occurrence of extreme temperature events causes significant economic losses to the livestock industry. Therefore, delving into the differences in the physiological and molecular mechanisms of heat stress across different sheep breeds is crucial for developing effective management and breeding strategies. This study explores the differences in heat tolerance mechanisms between Hu sheep and Xinggao sheep by comparing their growth performance under normal and heat stress conditions, as well as examining the differences in physiological, biochemical, and antioxidant indicators related to heat tolerance, serum metabolomics, and gut microbiomics in a heat stress environment. The results indicate that with changes in the temperature-humidity index (THI), Hu sheep exhibit superior stability in respiratory rate (RR) and rectal temperature (RT) fluctuations compared to Xinggao sheep. In terms of biochemical indicators and antioxidant capacity, the levels of creatinine (Cr) and superoxide dismutase (SOD) in Hu sheep serum are significantly higher than those in Xinggao sheep. In comparison, alkaline phosphatase (ALP) and malondialdehyde (MDA) levels are significantly lower. Metabolomic results showed that, compared to Hu sheep, Xinggao sheep exhibited higher cortisol (COR) and dopamine (DA) levels under heat stress conditions, a stronger lipid mobilization capacity, and elevated levels of tricarboxylic acid (TCA) cycle-related metabolites. Furthermore, gut microbiome analysis results indicate that Hu sheep demonstrate stronger cellulose degradation capabilities, as evidenced by significantly higher abundances of microorganisms such as Ruminococcus, Fibrobacter, and Bacteroidales_RF16_group, compared to Xinggao sheep. In summary, Hu sheep exhibit stronger heat tolerance compared to Xinggao sheep. These findings provide an important theoretical basis for the breeding and selection of heat-tolerant meat sheep varieties and offer strong support for the region's livestock industry in addressing the challenges posed by global warming.

Important ecophysiological roles of Nocardiopsis in lignocellulose degradation during aerobic compost with humic acid addition.

Improving lignocellulose degradation and organic matter conversion in agricultural and livestock wastes remains a great challenge. Here, the contribution of humic acid (HA) to lignocellulose degradation was investigated, focusing on the abundance of key microbial species and carbohydrate-active enzymes during aerobic composting. The results demonstrated that the addition of HA not only increased the complexity of the microbial network, but also enhanced the positive interaction between microorganism. The abundance of phylum Actinobacteria related to lignin degradation was significantly increased, especially genus Nocardiopsis (50.97 %), and Nocardiopsis was significantly positively correlated with HA and humus (HS) (p<0.05). Additionally, the abundance of GH (43.45%) and AA (5.88%) enzymes and the activation of metabolic pathways of AA, carbohydrates and energy were significantly increased (p<0.05). Remarkably, the quantity of lignocellulose-degrading genes and carbohydrate-active enzymes experienced a marked boost (p<0.05), with the peak abundance observed in Nocardiopsis. The structural equation model revealed that the addition of HA boosted the abundance of Nocardiopsis, which in turn amplified lignocellulose degradation by up-regulating lignocellulose degradation genes and enhancing carbohydrase activity, and facilitating the conversion of HA and FA. The lignocellulose degradation experiment verified that Nocardiopsis alba exhibited good ability in the degradation of cellulose and hemicellulose. These findings provided a novel perspective on the mechanisms underlying lignocellulose degradation, and broaden the understanding of the ecophysiological role of Nocardiopsis in composting system.

Enhanced biomethane production by thermophilic high-solid anaerobic co-digestion of rice straw and food waste: Cellulose degradation and microbial structure

Enhanced biomethane production by thermophilic high-solid anaerobic co-digestion of rice straw and food waste: Cellulose degradation and microbial structure

Oxidative cleavage of cellulose by fungi in the termite gut

Lytic polysaccharide monooxygenases (LPMOs) of auxiliary activity family 9 (AA9) oxidatively degrade cellulose. Cellulose is degraded by cellulases via hydrolysis in the termite gut. However, it remains uncertain whether oxidative cleavage of cellulose occurs within the termite gut. In this study, we report for the first time experimental support for the oxidative cleavage of cellulose in the termite (Cryptotermes declivis) gut. We identified the varieties of fungi in the termite gut through extensive analysis of the isolated fungi and sequencing of the internal transcribed spacer region. Most of the fungi were Ascomycetes. Genome sequencing revealed the presence of an AA9 LPMO (TfAA9A) in one of the isolated species, Talaromyces funiculosus. The expression of TfAA9A in the termite gut was detected using reverse transcription–polymerase chain reaction, and its ability to oxidize cellulose was confirmed in vitro through heterologous gene expression in Pichia pastoris and cellulose degradation experiments with the purified enzyme. Further transcriptome and proteomics analyses showed mRNA and protein expression of fungal AA9 LPMOs in the termite gut. These experimental data support the oxidative cleavage of cellulose in the termite gut. This study offers a new direction for understanding the mechanism of cellulose degradation in termites.

Enhancing the water resistance properties of bamboo particleboard by reconstructing lignocellulose through carbonization treatment

Bamboo particleboards are recognized as a highly promising alternative to traditional wood particleboards owing to their short growth cycle, abundant availability, and exceptional mechanical properties. However, bamboo particleboards frequently exhibit undesirable hygroscopicity, which limits their broader applications. This study introduces a straightforward and inhibitor-free carbonization treatment method to enhance the water resistance properties of bamboo particleboards. During the carbonization process, the degradation of hemicelluloses and amorphous cellulose, combined with the condensation reactions among lignin molecules, leads to a significant reduction in the hydrophilic hydroxyl and carbonyl group content, resulting in a more compact micro-fibril structure. Concurrently, the degradation of specific macromolecules within the cell wall facilitates the crushing of bamboo during particleboard pressing, thereby reducing the macroscopic pore size between the particles in the board. When compared to the original bamboo particleboard, the moisture absorption, 24-h water absorption (at a relative humidity of 50 %), 24-h thickness swelling, and bound water content of the deep carbon bamboo particleboard decreased by 32.28 %, 81.57 %, 67.16 %, and 66.7 %, respectively, while the water contact angle increased by 88.89 %.

Impact of cellulose degradation on space charge dynamics and dielectric properties of Kraft paper impregnated with ester liquid in comparison with mineral oil

AbstractApplying environmentally friendly ester liquids in high‐voltage direct current (HVDC) converter transformers is a technological ambition that requires research on their performance under DC voltages. This paper researched ester liquid‐impregnated Kraft paper through experimentally investigating space charges and dielectric properties under HVDC fields. The study focused mainly on the influence of cellulose degradation. Hence, Kraft papers of different degree of polymerisation impregnated with fresh ester liquid and fresh mineral oil were tested, and their space charges, electric field distortion, conductivity and permittivity were evaluated. Strong correlations were found between these parameters. Electric field distortion in fresh ester liquid‐impregnated paper (ELIP) was higher than that in fresh mineral oil‐impregnated paper (MOIP) but remained almost constant with paper‐ageing. However, electric field distortion increased noticeably in MOIP with paper‐ageing and became higher than that in ELIP. Thus, electric field distortion resulted from space charges and conductivity mismatch under new and ageing conditions must be considered in designing the insulation systems of converter transformers.

Methacrylated gellan gum microgels: A further step in the gel-based cleaning system

Paper has been entrusted with a large portion of humanity's recorded knowledge in recent centuries, therefore its preservation is fundamental for maintaining cultural heritage. Indeed, cellulose—the primary material of these artifacts— goes through irreversible degradation processes as it ages, leading to a weakening of paper stability and color changes. In order to slow down ageing, several restoration strategies involving the use of wet cleaning by hydrogels can be found in literature. Multi-step treatments are often required to complete the cleaning procedure, as the properties of contaminants greatly vary from a chemical–physical point of view (i.e. hydrophilic, hydrophobic or, as for adhesives, polymeric compounds). In this article, we propose a cleaning strategy that accounts for the inherent roughness of paper by developing microgel particles made of methacrylated gellan gum. Microgel particles are smaller than their macroscopic counterparts, hydrogels, and as a result, they can clean paper more quickly, a few minutes as opposed to hours. Moreover, the chemical modification performed on deacylated gellan gum makes the polymer more hydrophobic, as compared to the unmodified one. In this way, the proposed microgels are able to interact with and adsorb not only hydrophilic by-products of cellulose degradation, as gellan gum-based microgels do, but also hydrophobic materials or synthetic adhesives. This procedure represents a valid strategy, safe for operators, for the cleaning of paper artworks as it avoids the use of potentially dangerous organic solvents for hydrophobic material removal.

Study on the Aging Effects of Relative Humidity on the Primary Chemical Components of Palm Leaf Manuscripts.

Palm Leaf Manuscripts represent a significant component of the world's cultural heritage. Investigating their primary chemical components and understanding the transformations these materials undergo under environmental influences are crucial for elucidating their material characteristics and aging mechanisms and developing effective strategies for preventive conservation. This study utilized infrared absorption spectroscopy and X-ray diffraction analysis to examine changes in the primary chemical components of Palm Leaf Manuscripts under varying relative humidity conditions over extended periods. The findings reveal that dry environments lead to surface cracking, while humid environments promote mold growth, both of which contribute to the degradation of the primary chemical components. These degradative processes reduce cellulose crystallinity and thermal stability. The deterioration is particularly severe under high humidity, with hemicellulose degrading faster and more extensively than cellulose under the same conditions. After 200 days of aging at 10% RH and 90% RH, cellulose degradation reached 19.82% and 54.40%, respectively, while hemicellulose degradation was 34.78% and 64.28%. Correspondingly, the relative crystallinity of cellulose decreased by 8.01% and 13.11%. In contrast, samples maintained at 50% RH exhibited minimal deterioration, with cellulose and hemicellulose degrading by only 4.08% and 13.55%, respectively, and a 6.61% reduction in cellulose crystallinity. These results suggest that a relative humidity of 50% is optimal for the preservation of Palm Leaf Manuscripts. This study offers significant insights into the ageing mechanisms and preventive conservation of Palm Leaf Manuscripts, as well as other cellulose-based organic heritage materials.

Metabolic enhancement contributed by horizontal gene transfer is essential for dietary specialization in leaf beetles

Horizontal gene transfer (HGT) from bacteria to insects is widely reported and often associated with the adaptation and diversification of insects. However, compelling evidence demonstrating how HGT-conferred metabolic adjustments enable species to adapt to surrounding environment remains scarce. Dietary specialization is an important ecological strategy adopted by animals to reduce inter- and intraspecific competition for limited resources. Adults of the leaf beetle Plagiodera versicolora (Coleoptera) preferentially consume new leaves; nevertheless, we found that they selectively oviposit on mature leaves, thereby establishing a distinct dietary niche separation between adults and larvae. Based on the de novo assembled chromosome-level genome, we identified two horizontally transferred genes with cellulose degradation potential, belonging to the glycosyl hydrolase 48 family (GH48-1 and GH48-2). Prokaryotic expression of the HGTs confirmed the cellulose degradation capability of the two genes. Knockdown of GH48 significantly hampered the growth and survival rate of larvae feeding on mature leaves compared to wild-type larvae, with no similar effect observed in adults. Replenishing the GH48-expressing bacteria compensated for the knockdown of these two genes and recurred larval adaptability to mature leaves. Taken together, our results highlight the advantage and metabolic enhancement conferred by the two cellulose-degrading HGTs in P. versicolora larvae, enabling their development on cellulose-enriched mature leaves and underscoring the indispensable role of HGTs in facilitating the adaptation of leaf beetles to plants.

Similarity in the microbial community structure of tobacco from geographically similar regions

To investigate the structural and functional similarities of microbial communities in burnt-sweetness alcoholized tobacco as a function of distance from the equator and their effects on tobacco quality, we sampled alcoholized tobacco from Chenzhou, Hunan Province, China and from Brazil and Zimbabwe, which are also burnt-sweetness-type tobacco producing regions, and performed high-throughput sequencing of tobacco bacterial and fungal communities along with an analysis of the main chemical constituents of the tobacco to analyze differences in the quality of the tobacco and similarities in the structure of the microbial communities. The total nitrogen, nicotine and starch contents of Chenzhou tobacco were greater than those of Brazilian and Zimbabwean tobacco, and the total sugar and reducing sugar contents of the Brazilian and Zimbabwean tobacco were greater than those of the Chenzhou tobacco (P < 0.05). The alpha diversity indices of the bacterial communities in Chenzhou tobacco were lower than those in the Brazilian and Zimbabwean tobacco, and the alpha diversity indices of the fungal communities in Chenzhou tobacco were greater than those in the Brazilian and Zimbabwean tobacco (P < 0.05). In the ecological networks, bacterial–fungal interactions in the Brazilian and Zimbabwean tobacco were more complex than those in the Chenzhou tobacco, and the microbial ecological networks of the burnt-sweetness-type tobacco from three different regions were dominated by competitive relationships. The microbial community composition of Chenzhou tobacco was similar to that of Brazilian tobacco at the bacterial genus and fungal phylum level, with Sphingomonas being a significantly enriched genus in Brazilian tobacco and a key genus in the Chenzhou network that is able to participate in the degradation of polyphenols and aromatic compounds. Functional microbes related to aromatic compounds and cellulose degradation were significantly more abundant in the Brazilian and Zimbabwean tobacco than in Chenzhou tobacco, and the related degradation of tobacco substances was responsible for the better quality of the Brazilian and Zimbabwean tobacco. In conclusion, there are similarities in the structure, composition and functional flora of microbial communities in tobacco from Chenzhou and Brazil because these regions have similar latitudinal distributions. This study provides theoretical support for selecting cultivation regions for the burnt-sweetness-type alcoholized tobacco and for the alcoholization of tobacco leaves.