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The red palm weevil (RPW), Rhynchophorus ferrugineus, poses a significant threat to date palms globally, heavily relying on symbiotic microbes for various physiological and behavioral functions. This comprehensive study delves into the intricate dynamics of RPW gut microbiota, revealing a diverse microbial community consisting of seven genera and eight species from Proteobacteria, Firmicutes, and Actinobacteria. The stability of gut bacteria across different life stages was observed, with notable impacts on larval metabolism attributed to shifts in bacterial composition. Bacillus subtilis emerged as a key player, producing a spectrum of metabolic enzymes. Furthermore, the gut bacteria exhibited remarkable pesticide degradation capabilities, suggesting a potential role in the host's resistance to pesticides. The Arthrobacter sp. was identified as a promising candidate for eco-friendly pest biocontrol and biodegradation strategies. Investigating the influence of thermal stress on two groups of RPW larvae (conventional-fed and antibiotic-fed) at varying temperatures (15, 27, and 35 °C) unveiled potential survival implications. This study highlights the pivotal role of bacterial symbionts in enabling larvae adaptation and thermal stress tolerance. In essence, this research contributes crucial insights into the diversity and functions of RPW gut bacteria, emphasizing their prospective applications in pest control strategies. [ABSTRACT FROM AUTHOR]

β-glucosidase is a key component of cellulase for its function in hydrolyzing cellobiose to glucose in the final step of cellulose degradation. The high-level expression of β-glucosidase is essential for cellulose conversion. Aspergillus niger ATCC 20611 has the potential for efficient protein expression because of its ability to secret enzymes for the industrial production of fructooligosaccharides, but it lacks robust promoters for high-level protein expression. Here, the development of A. niger 20611 as a powerful protein expression system exploited the conserved constitutive promoter Pgpd1 of the glyceraldehyde-3-phosphate dehydrogenase-encoding gene from Trichoerma reesei to drive the expression of the enhanced green fluorescent protein in A. niger ATCC 20611. The mycelium of the transformant AGE9 exhibited intense fluorescence. Then, the promotor Pgpd1 was used to drive the expression of β-glucosidase and the enzyme activity of transformants AGB1 and AGB33 were 1.02 and 0.51 U/mL, respectively. These results demonstrate that the promotor Pgpd1 from T. reesei was applicable for A. niger ATCC 20611. Furthermore, the T. reesei-specific robust promoter Pcdna1 was used to drive the expression of β-glucosidase. The β-glucosidase exhibited a high-level expression with a yield of 15.2 U/mL, which was over 13.9 times higher than that driven by the promoter Pgpd1. The β-glucosidase was thermally stable and accounted for 85% of the total extracellular proteins. Subsequently, the fermentation broth including β-glucosidase was directly added to the cellulase mixture of T. reesei for saccharification of the acid-treated corncob residues and the delignified corncob residues, which increased the saccharification efficiency by 26.21% and 29.51%, respectively. Thus, β-glucosidase exhibited a high level of expression in A. niger ATCC 20611 and enhanced cellulose degradation by addition in vitro. In addition, the robust promoter Pcdna1 of T. reesei could drive the high-level expression of protein in A. niger ATCC 20611. These results demonstrate that the promoters in filamentous fungi could be employed across species in A. niger ATCC 20611 and further facilitated the efficient expression of β-glucosidase to optimize cellulases for efficient cellulose transformation. [ABSTRACT FROM AUTHOR]

Simple Summary: Rodents, as the most abundant group of mammals, offer a unique opportunity to study the relationship between diet and host gut microecology. In this study, we focused on two species of the genus Myospalax in the Eurasian steppes in China: M. psilurus and M. aspalax. These specialized herbivorous rodents have adapted to a subterranean lifestyle and exhibit distinct dietary choices. Our study aimed to investigate how their diet composition is related to their gut microbial communities and whether there are unique indicator species for their gut microecology. Using 16S amplicon technology and macro-barcoding technology, we analyzed the gut bacterial communities and diet composition of the two zokor species. We found that M. psilurus had a higher diversity of gut microbial bacterial communities compared to M. aspalax. The two species also possessed different gut bacterial indicator species, with unique relationships between their diet and gut microbes. Our results provide new insights into the adaptation of zokors to long-term subterranean life and shed light on their cellulose degradation abilities and ecological niches. As the most abundant group of mammals, rodents possess a very rich ecotype, which makes them ideal for studying the relationship between diet and host gut microecology. Zokors are specialized herbivorous rodents adapted to living underground. Unlike more generalized herbivorous rodents, they feed on the underground parts of grassland plants. There are two species of the genus Myospalax in the Eurasian steppes in China: one is Myospalax psilurus, which inhabits meadow grasslands and forest edge areas, and the other is M. aspalax, which inhabits typical grassland areas. How are the dietary choices of the two species adapted to long-term subterranean life, and what is the relationship of this diet with gut microbes? Are there unique indicator genera for their gut microbial communities? Relevant factors, such as the ability of both species to degrade cellulose, are not yet clear. In this study, we analyzed the gut bacterial communities and diet compositions of two species of zokors using 16S amplicon technology combined with macro-barcoding technology. We found that the diversity of gut microbial bacterial communities in M. psilurus was significantly higher than that in M. aspalax, and that the two species of zokors possessed different gut bacterial indicator genera. Differences in the feeding habits of the two species of zokors stem from food composition rather than diversity. Based on the results of Mantel analyses, the gut bacterial community of M. aspalax showed a significant positive correlation with the creeping-rooted type food, and there was a complementary relationship between the axis root-type-food- and the rhizome-type-food-dominated (containing bulb types and tuberous root types) food groups. Functional prediction based on KEGG found that M. psilurus possessed a stronger degradation ability in the same cellulose degradation pathway. Neutral modeling results show that the gut flora of the M. psilurus has a wider ecological niche compared to that of the M. aspalax. This provides a new perspective for understanding how rodents living underground in grassland areas respond to changes in food conditions. [ABSTRACT FROM AUTHOR]

Cellulolytic microorganisms play a crucial role in agricultural waste disposal. Strain QXD-8T was isolated from soil in northern China. Similarity analyses of the 16S rRNA gene, as well as the 120 conserved genes in the whole-genome sequence, indicate that it represents a novel species within the genus Microbacterium. The Microbacterium sp. QXD-8T was able to grow on the CAM plate with sodium carboxymethyl cellulose as a carbon source at 15 °C, forming a transparent hydrolysis circle after Congo red staining, even though the optimal temperature for the growth and cellulose degradation of strain QXD-8T was 28 °C. In the liquid medium, it effectively degraded cellulose and produced reducing sugars. Functional annotation revealed the presence of encoding genes for the GH5, GH6, and GH10 enzyme families with endoglucanase activity, as well as the GH1, GH3, GH39, and GH116 enzyme families with β-glucosidase activity. Additionally, two proteins in the GH6 family, one in the GH10, and two of nine proteins in the GH3 were predicted to contain a signal peptide and transmembrane region, suggesting their potential for extracellularly degrade cellulose. Based on the physiological features of the type strain QXD-8T, we propose the name Microbacterium psychrotolerans for this novel species. This study expands the diversity of psychrotolerant cellulolytic bacteria and provides a potential microbial resource for straw returning in high-latitude areas at low temperatures. [ABSTRACT FROM AUTHOR]

Actinomycetes are an important group of bioactive hydrolytic bacteria in any ecosystem. However, the actinomycete biodiversity in tropical ecosystems, particularly in Vietnam, is still underexplored. The aim of this article is to analyze the abundance, taxonomic structure and ecophysiological features of actinomycete complexes of soils and litter in Vietnam's protected areas. A total of 41 samples of soils, plant litter and suspended soils were collected from six of Vietnam's national parks and nature reserves. The direct inoculation technique showed that the total abundance of actinomycetes varied from 2.0 × 104 to 1.0 × 108 CFU/g. According to the luminescent microscopy with acridine orange dye, the length of the actinomycete mycelium was as long as 1000 m/g in the litter of Xuan Son National Park. A total of 80 strains were isolated and tested for antagonistic activity against Bacillus subtilis, Aspergillus niger and Candida albicans. Inoculation on Getchinson's medium showed high cellulolytic activity. The most active strains were isolated from alluvial brown soil, plant litter and suspended soil of the Pu Hoat Nature Reserve. In these samples, actinomycetes adapted to high temperatures and low pH were found to be predominant. High-throughput sequencing of the V3–V4 region of the 16S rRNA gene and bioinformatic analysis confirmed the high taxonomic diversity and high hydrolytic activity of actinomycete complexes of the Pu Hoat Nature Reserve samples. [ABSTRACT FROM AUTHOR]

In 2021, Wide-angle X-ray Scattering (WAXS) was applied to a sample of the Turin Shroud as a new method for dating ancient linen threads by inspecting their structural degradation. The major result of the research was to estimate the natural aging of the linen of the Shroud, through which it was found to be compatible with the hypothesis of a 2000-year-old relic, and not a medieval fabric. The present work regards the theoretical natural aging of the linen versus different alleged historical–geographical paths of the Shroud through cities where the presence of icons of Jesus Christ is attested. The theoretical results of the natural aging of the Shroud, calculated for the year 2021, agree extremely well with the experimental results for at least one alleged path. The results also show that if the Shroud were medieval and kept in Europe for 7 centuries, natural aging that is one order of magnitude less than that measured by WAXS would have resulted. Today, the Shroud is kept in a reliquary with a controlled atmosphere, at 19~20 °C temperature, and 50% relative humidity. These values are shown to be unsuitable for maintaining the depolymerization of the cellulose at a level that is sufficiently low enough to preserve the image visible on the Shroud for a long time. [ABSTRACT FROM AUTHOR]

Biofilm commonly forms on the surfaces of cellulosic biomass but its roles in cellulose degradation remain largely unexplored. We used Bacillus subtilis to study possible mechanisms and the contributions of two major biofilm components, extracellular polysaccharides (EPS) and TasA protein, to submerged biofilm formation on cellulose and its degradation. We found that biofilm produced by B. subtilis is able to absorb exogenous cellulase added to the culture medium and also retain self-produced cellulase within the biofilm matrix. The bacteria that produced more biofilm degraded more cellulose compared to strains that produced less biofilm. Knockout strains that lacked both EPS and TasA formed a smaller amount of submerged biofilm on cellulose than the wild-type strain and also degraded less cellulose. Imaging of biofilm on cellulose suggests that bacteria, cellulose, and cellulases form cellulolytic biofilm complexes that facilitate synergistic cellulose degradation. This study brings additional insight into the important functions of biofilm in cellulose degradation and could potentiate the development of biofilm-based technology to enhance biomass degradation for biofuel production. [ABSTRACT FROM AUTHOR]

On a sample of the Turin Shroud (TS), we applied a new method for dating ancient linen threads by inspecting their structural degradation by means of Wide-Angle X-ray Scattering (WAXS). The X-ray dating method was applied to a sample of the TS consisting of a thread taken in proximity of the 1988/radiocarbon area (corner of the TS corresponding to the feet area of the frontal image, near the so-called Raes sample). The size of the linen sample was about 0.5 mm × 1 mm. We obtained one-dimensional integrated WAXS data profiles for the TS sample, which were fully compatible with the analogous measurements obtained on a linen sample whose dating, according to historical records, is 55–74 AD, Siege of Masada (Israel). The degree of natural aging of the cellulose that constitutes the linen of the investigated sample, obtained by X-ray analysis, showed that the TS fabric is much older than the seven centuries proposed by the 1988 radiocarbon dating. The experimental results are compatible with the hypothesis that the TS is a 2000-year-old relic, as supposed by Christian tradition, under the condition that it was kept at suitable levels of average secular temperature—20.0–22.5 °C—and correlated relative humidity—75–55%—for 13 centuries of unknown history, in addition to the seven centuries of known history in Europe. To make the present result compatible with that of the 1988 radiocarbon test, the TS should have been conserved during its hypothetical seven centuries of life at a secular room temperature very close to the maximum values registered on the earth. [ABSTRACT FROM AUTHOR]

β-Glucosidases (Bgls) convert cellobiose and other soluble cello-oligomers into glucose and play important roles in fundamental biological processes, providing energy sources in living organisms. Bgls are essential terminal enzymes of cellulose degradation systems and attractive targets for lignocellulose-based biotechnological applications. Characterization of novel Bgls is important for broadening our knowledge of this enzyme class and can provide insights into its further applications. In this study, we report the biochemical and structural analysis of a Bgl from the hemicellulosedegrading thermophilic anaerobe Thermoanaerobacterium saccharolyticum (TsaBgl). TsaBgl exhibited its maximum hydrolase activity on p-nitrophenyl-β-D-glucopyranoside at pH 6.0 and 55 ◦C. The crystal structure of TsaBgl showed a single (β/α)8 TIM-barrel fold, and a β8-α14 loop, which is located around the substrate-binding pocket entrance, showing a unique conformation compared with other structurally known Bgls. A Tris molecule inhibited enzyme activity and was bound to the active site of TsaBgl coordinated by the catalytic residues Glu163 (proton donor) and Glu351 (nucleophile). Titration experiments showed that TsaBgl belongs to the glucose-tolerant Bgl family. The gatekeeper site of TsaBgl is similar to those of other glucose-tolerant Bgls, whereas Trp323 and Leu170, which are involved in glucose tolerance, show a unique configuration. Our results therefore improve our knowledge about the Tris-mediated inhibition and glucose tolerance of Bgl family members, which is essential for their industrial application. [ABSTRACT FROM AUTHOR]

Auxiliary activity 9 (AA9) lytic polysaccharide monooxygenases (LPMOs) are copper-dependent oxidoreductases that use O2 or H2O2 to perform oxidative cleavage of cellulose in the presence of an electron donor. Combined with cellulases, they can assist in a more efficient cleavage of cellulose. AA9 LPMOs have therefore attracted considerable attention in recent years for use in biotechnological applications. Here, a native AA9 LPMO (nTaAA9A) from the thermophilic fungus Thermoascus aurantiacus was purified and characterized. The enzyme was shown to be active and able to cleave cellulose and xylan to produce C1- and C4-oxidized products. It was also found to retain about 84.3, 63.7, and 35.3% of its activity after incubation for 30 min at 60, 70, and 80 °C, respectively, using quantitative activity determination. The structure was determined to 1.36 Å resolution and compared with that of the recombinant enzyme expressed in Aspergillus oryzae. Structural differences in the glycosylated Asn138 and in solvent-exposed loops were identified. [ABSTRACT FROM AUTHOR]

Fish play a critical role in nutrient cycling and organic matter flow in aquatic environments. However, little is known about the microbial diversity within the gastrointestinal tracts that may be essential in these degradation activities. Panaque nigrolineatus is a loricariid catfish found in the Neotropics that have a rare dietary strategy of consuming large amounts of woody material in its natural environment. As a consequence, the gastrointestinal (GI) tract of P. nigrolineatus is continually exposed to high levels of cellulose and other recalcitrant wood compounds and is, therefore, an attractive, uncharacterized system to study microbial community diversity. Our previous 16S rRNA gene surveys demonstrated that the GI tract microbial community includes phylotypes having the capacity to degrade cellulose and fix molecular nitrogen. In the present study we verify the presence of a resident microbial community by fluorescence microscopy and focus on the cellulose-degrading members by culture-based and 13C-labeled cellulose DNA stable-isotope probing (SIP) approaches. Analysis of GI tract communities generated from anaerobic microcrystalline cellulose enrichment cultures by 16S rRNA gene analysis revealed phylotypes sharing high sequence similarity to known cellulolytic bacteria including Clostridium, Cellulomonas, Bacteroides, Eubacterium and Aeromonas spp. Related bacteria were identified in the SIP community, which also included nitrogen-fixing Azospirillum spp. Our ability to enrich for specialized cellulose-degrading communities suggests that the P. nigrolineatus GI tract provides a favorable environment for this activity and these communities may be involved in providing assimilable carbon under challenging dietary conditions. [ABSTRACT FROM AUTHOR]

β-Glucosidases (Bgls) convert cellobiose and other soluble cello-oligomers into glucose and play important roles in fundamental biological processes, providing energy sources in living organisms. Bgls are essential terminal enzymes of cellulose degradation systems and attractive targets for lignocellulose-based biotechnological applications. Characterization of novel Bgls is important for broadening our knowledge of this enzyme class and can provide insights into its further applications. In this study, we report the biochemical and structural analysis of a Bgl from the hemicellulose-degrading thermophilic anaerobe Thermoanaerobacterium saccharolyticum (TsaBgl). TsaBgl exhibited its maximum hydrolase activity on p -nitrophenyl-β-d-glucopyranoside at pH 6.0 and 55 °C. The crystal structure of TsaBgl showed a single (β/α) 8 TIM-barrel fold, and a β8-α14 loop, which is located around the substrate-binding pocket entrance, showing a unique conformation compared with other structurally known Bgls. A Tris molecule inhibited enzyme activity and was bound to the active site of TsaBgl coordinated by the catalytic residues Glu163 (proton donor) and Glu351 (nucleophile). Titration experiments showed that TsaBgl belongs to the glucose-tolerant Bgl family. The gatekeeper site of TsaBgl is similar to those of other glucose-tolerant Bgls, whereas Trp323 and Leu170, which are involved in glucose tolerance, show a unique configuration. Our results therefore improve our knowledge about the Tris-mediated inhibition and glucose tolerance of Bgl family members, which is essential for their industrial application.

The degradation of cellulose is an important factor influencing its mechanical, optical, physical, and chemical properties and, hence, the lifetime of paper in libraries and archival collections. Regardless of the complexity of the paper material, the main chemical pathways for its degradation are hydrolysis and oxidation. This study presents an overview of the analytical techniques employed in the evaluation of the hydrolysis and oxidation processes; these techniques include size-exclusion chromatography, Fourier-transform infrared and ultraviolet–visible spectroscopy, and X-ray diffraction. This paper aims to determine the extent to which these instrumental methods are useful for studying the aforementioned processes and for which lignin contents. It also highlights how atmospheric humidity could affect the cellulose structure in paper containing lignin. It was found that humidity causes significant changes in the cellulose chain lengths and that a high lignin content in paper could suppress some cellulose degradation pathways. This knowledge can be applied to developing strategies and selective chemical treatments preventing the consequences of paper ageing. [ABSTRACT FROM AUTHOR]

Solid-state nuclear magnetic resonance (ssNMR) spectroscopy provides information on native structures and the dynamics for predicting and designing the physical properties of multi-component solid materials. However, such an analysis is difficult because of the broad and overlapping spectra of these materials. Therefore, signal deconvolution and prediction are great challenges for their ssNMR analysis. We examined signal deconvolution methods using a short-time Fourier transform (STFT) and a non-negative tensor/matrix factorization (NTF, NMF), and methods for predicting NMR signals and physical properties using generative topographic mapping regression (GTMR). We demonstrated the applications for macromolecular samples involved in cellulose degradation, plastics, and microalgae such as Euglena gracilis. During cellulose degradation, 13C cross-polarization (CP)–magic angle spinning spectra were separated into signals of cellulose, proteins, and lipids by STFT and NTF. GTMR accurately predicted cellulose degradation for catabolic products such as acetate and CO2. Using these methods, the 1H anisotropic spectrum of poly-ε-caprolactone was separated into the signals of crystalline and amorphous solids. Forward prediction and inverse prediction of GTMR were used to compute STFT-processed NMR signals from the physical properties of polylactic acid. These signal deconvolution and prediction methods for ssNMR spectra of macromolecules can resolve the problem of overlapping spectra and support macromolecular characterization and material design. [ABSTRACT FROM AUTHOR]

Bacterial hydrolysis of polysaccharides is an important step for the production of sustainable energy, for example during the conversion of plant biomass to methane-rich biogas. Previously, Hungateiclostridium thermocellum was identified as cellulolytic key player in thermophilic biogas microbiomes with a great frequency as an accompanying organism. The aim of this study was to physiologically characterize a recently isolated co-culture of H. thermocellum and the saccharolytic bacterium Defluviitalea raffinosedens from a laboratory-scale biogas fermenter. The characterization focused on cellulose breakdown by applying the measurement of cellulose hydrolysis, production of metabolites, and the activity of secreted enzymes. Substrate degradation and the production of volatile metabolites was considerably enhanced when both organisms acted synergistically. The metabolic properties of H. thermocellum have been studied well in the past. To predict the role of D. raffinosedens in this bacterial duet, the genome of D. raffinosedens was sequenced for the first time. Concomitantly, to deduce the prevalence of D. raffinosedens in anaerobic digestion, taxonomic composition and transcriptional activity of different biogas microbiomes were analyzed in detail. Defluviitalea was abundant and metabolically active in reactor operating at highly efficient process conditions, supporting the importance of this organism for the hydrolysis of the raw substrate. [ABSTRACT FROM AUTHOR]

Beta-glucosidases (β-glucosidases) have attracted considerable attention in recent years for use in various biotechnological applications. They are also essential enzymes for lignocellulose degradation in biofuel production. However, cost-effective biomass conversion requires the use of highly efficient enzymes. Thus, the search for new enzymes as better alternatives of the currently available enzyme preparations is highly important. Thermophilic fungi are nowadays considered as a promising source of enzymes with improved stability. Here, the crystal structure of a family GH3 β-glucosidase from the thermophilic fungus Chaetomium thermophilum (CtBGL) was determined at a resolution of 2.99 Å. The structure showed the three-domain architecture found in other β-glucosidases with variations in loops and linker regions. The active site catalytic residues in CtBGL were identified as Asp287 (nucleophile) and Glu517 (acid/base). Structural comparison of CtBGL with Protein Data Bank (PDB)-deposited structures revealed variations among glycosylated Asn residues. The enzyme displayed moderate glycosylation compared to other GH3 family β-glucosidases with similar structure. A new glycosylation site at position Asn504 was identified in CtBGL. Moreover, comparison with respect to several thermostability parameters suggested that glycosylation and charged residues involved in electrostatic interactions may contribute to the stability of the enzyme at elevated temperatures. The reported CtBGL structure provides additional insights into the family GH3 enzymes and could offer new ideas for further improvements in β-glucosidases for more efficient use in biotechnological applications regarding cellulose degradation. [ABSTRACT FROM AUTHOR]

This manuscript presents a comprehensive literature review with the aim to provide readers a reference document with up-to-date information on the field of methanol use as a chemical marker. It has been a little more than a decade since methanol was first introduced as a marker for assessing solid insulation condition in power transformers. It all started when methanol was identified in the laboratory during thermal ageing tests carried out with oil-immersed insulating papers and was subsequently also identified in transformer field samples. The first publication on the subject was released in 2007 by our research group. This review covers the methanol fundamentals such as the analytical methods for its determination in transformer oil, which is generally performed by headspace gas chromatography with mass spectrometry or flame ionization as a detector. Current standardization efforts for its determination include ASTM working group 30948 and IEC TC10. Kinetic studies have confirmed the relationship between methanol generation, the number of broken 1,4-β-glycosidic bonds of cellulose and changes in mechanical properties. Laboratory tests have confirmed its stability at different accelerated ageing temperatures. Several utilities have identified methanol during field measurements, case studies on power and some distribution transformers are presented, as well as transformer postmortem investigations. These field-testing results demonstrate its utility in monitoring cellulosic insulation degradation. Recently, a model of methanol interpretation has become available that allows for evaluation of the average degree of polymerization of core type transformer cellulose winding. Methanol has a role as an indicator of cellulosic solid insulation ageing in transformer mineral oil, and it is expected that in the future it will be in routine use by utilities. [ABSTRACT FROM AUTHOR]

β-Glucosidases are key enzymes in the process of cellulose utilization. It is the last enzyme in the cellulose hydrolysis chain, which converts cellobiose to glucose. Since cellobiose is known to have a feedback inhibitory effect on a variety of cellulases, β-glucosidase can prevent this inhibition by hydrolyzing cellobiose to non-inhibitory glucose. While the optimal temperature of the Clostridium thermocellum cellulosome is 70 °C, C. thermocellum β-glucosidase A is almost inactive at such high temperatures. Thus, in the current study, a random mutagenesis directed evolutionary approach was conducted to produce a thermostable mutant with Kcat and Km, similar to those of the wild-type enzyme. The resultant mutant contained two mutations, A17S and K268N, but only the former was found to affect thermostability, whereby the inflection temperature (Ti) was increased by 6.4 °C. A17 is located near the central cavity of the native enzyme. Interestingly, multiple alignments revealed that position 17 is relatively conserved, whereby alanine is replaced only by serine. Upon the addition of the thermostable mutant to the C. thermocellum secretome for subsequent hydrolysis of microcrystalline cellulose at 70 °C, a higher soluble glucose yield (243%) was obtained compared to the activity of the secretome supplemented with the wild-type enzyme. [ABSTRACT FROM AUTHOR]

Biomass conversion to 5-hydroxymethylfurfural (HMF) has been widely investigated as a sustainable alternative to petroleum-based feedstock, since it can be efficiently converted to fuel, plastic, polyester, and other industrial chemicals. In this report, the degradation of commercial cellulose, the isomerization of glucose to fructose, and the conversion of glucose to HMF in 1-butyl-3-methylimidazolium chloride ([BMIM]Cl]) using metal catalysts (CrCl3, ZnCl2, MgCl2) as well as tungsten and molybdenum oxide-based polyoxometalates (POM) were investigated. Tungsten and molybdenum oxide-based POMs in ionic liquids (IL) were able to degrade cellulose to majority glucose and epimerize glucose to mannose (in the case of the molybdenum oxide-based POM). A certain amount of glucose was also converted to HMF. The tungsten oxide-based POM in IL showed good activity for cellulose degradation but the overall products yield remained 28.6% lower than those obtained using CrCl3 as a catalyst. Lowering the cellulose loading did not significantly influence the results and the addition of water to the reaction medium decreased the product yields remarkably. [ABSTRACT FROM AUTHOR]