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[Display omitted] • Inoculation of thermophilic bacterial consortia promoted the compost efficiency. • P V , n/P III , n values revealed the humification degree in different treatments. • Core microbes drove the variations in compost temperature, TOC, TN, and HAC. • Microbial community functions were closely related to compost quality. The objective of this study was to investigate the potential effects of thermophilic bacterial consortia on compost efficiency and quality. The application of bacterial consortia resulted in an earlier onset of the thermophilic period (THP), an increased upper temperature limit, and an extended duration of the THP by 3–5 days compared to the control group (CK). Microbial inoculation significantly improved the efficiency of organic matter degradation, as well as the content of water-soluble nitrogen (WSN) and humic acid-carbon (HAC). In the case of consortium Ⅱ inoculation (T2), the activities of cellobiohydrolase, β-glucosidase, and protease were increased by 81.81 %, 70.13 %, and 74.09 % at the THP respectively compared to CK. During the maturation stage, T2 also exhibited the highest P V , n/P III , n value (1.33) and HAC content (39.53 mg·g−1), indicating that inoculation of consortium Ⅱ effectively promoted substrate maturity and product quality. Moreover, this inoculation effectively optimized the bacterial communities, particularly the growth of Planococcus, Chelatococcus, and Chelativorans during the composting, which were involved in carbon and nitrogen conversion or HAC synthesis. Carbohydrate and amino acid metabolism, and membrane transport were predominant in the consortia-inoculated samples, with an increased gene abundance, suggesting that inoculation contributed to promoting the biodegradation of lignocellulose and the exchange of favorable factors. In conclusion, this study demonstrates that inoculating thermophilic bacterial consortia has a positive impact on enhancing the resource utilization efficiency of agricultural waste and improving the quality of compost products. [ABSTRACT FROM AUTHOR]

• A metaproteomics-based comparison of microbial degradation from ASP to AB was conducted. • Upgrading from ASP to AB increased lignocellulose degradation rates by 18.49-46.52%. • The upgrade from ASP to AB improved diversity of CAZyme-producing microbes. • AB but not ASP can produce the key enzyme for acetate conversion. • AB was superior to ASP for compost decomposition with higher cellulose. Composting presents a viable management solution for lignocellulose-rich municipal solid waste. However, our understanding about the microbial metabolic mechanisms involved in the biodegradation of lignocellulose, particularly in industrial-scale composting plants, remains limited. This study employed metaproteomics to compare the impact of upgrading from aerated static pile (ASP) to agitated bed (AB) systems on physicochemical parameters, lignocellulose biodegradation, and microbial metabolic pathways during large-scale biowaste composting process, marking the first investigation of its kind. The degradation rates of lignocellulose including cellulose, hemicellulose, and lignin were significantly higher in AB (8.21%-32.54%, 10.21%-39.41%, and 6.21%-26.78%) than those (5.72%-23.15%, 7.01%-33.26%, and 4.79%-19.76%) in ASP at three thermal stages, respectively. The AB system in comparison to ASP increased the carbohydrate-active enzymes (CAZymes) abundance and production of the three essential enzymes required for lignocellulose decomposition involving a mixture of bacteria and fungi (i.e., Actinobacteria, Bacilli, Sordariomycetes and Eurotiomycetes). Conversely, ASP primarily produced exoglucanase and β-glucosidase via fungi (i.e., Ascomycota). Moreover, AB effectively mitigated microbial stress caused by acetic acid accumulation by regulating the key enzymes involved in acetate conversion, including acetyl-coenzyme A synthetase and acetate kinase. Overall, the AB upgraded from ASP facilitated the lignocellulose degradation and fostered more diverse functional microbial communities in large-scale composting. Our findings offer a valuable scientific basis to guide the engineering feasibility and environmental sustainability for large-scale industrial composting plants for treating lignocellulose-rich waste. These findings have important implications for establishing green sustainable development models (e.g., a circular economy based on material recovery) and for achieving sustainable development goals. [Display omitted] [ABSTRACT FROM AUTHOR]

Anaerobic fungus–methanogen co-cultures from rumen liquids and faeces can degrade lignocellulose efficiently. In this study, 31 fungus–methanogen co-cultures were first obtained from the rumen of yaks grazing in Qinghai Province, China, using the Hungate roll-tube technique. The fungi were identified according to morphological characteristics and internal transcribed spacer (ITS) sequences. The methanogens associated with each fungus were identified by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) and 16S rRNA gene sequencing. They were five co-culture types: Neocallimastix frontalis + Methanobrevibacter ruminantium, Neocallimastix frontalis + Methanobrevibacter gottschalkii, Orpinomyces joyonii + Methanobrevibacter ruminantium, Caecomyces communis + Methanobrevibacter ruminantium, and Caecomyces communis + Methanobrevibacter millerae. Among the 31 co-cultures, during the 5-day incubation, the N. frontalis + M. gottschalkii co-culture YakQH5 degraded 59.0%–68.1% of the dry matter (DM) and 49.5%–59.7% of the neutral detergent fiber (NDF) of wheat straw, corn stalk, rice straw, oat straw and sorghum straw to produce CH4 (3.0–4.6 mmol/g DM) and acetate (7.3–8.6 mmol/g DM) as end-products. Ferulic acid (FA) released at 4.8 mg/g DM on corn stalk and p-coumaric acid (PCA) released at 11.7 mg/g DM on sorghum straw showed the highest values, with the following peak values of enzyme activities: xylanase at 12,910 mU/mL on wheat straw, ferulic acid esterase (FAE) at 10.5 mU/mL on corn stalk, and p-coumaric acid esterase (CAE) at 20.5 mU/mL on sorghum straw. The N. frontalis + M. gottschalkii co-culture YakQH5 from Qinghai yaks represents a new efficient combination for lignocellulose biodegradation, performing better than previously reported fungus–methanogen co-cultures from the digestive tract of ruminants. [ABSTRACT FROM AUTHOR]

Lignocellulose biomass (LCB) has extensive applications in many fields such as bioenergy, food, medicines, and raw materials for producing value‐added products. One of the keys to efficient utilization of LCB is to obtain directly available oligo‐ and monomers (e. g. glucose). With the characteristics of easy recovery and separation, high efficiency, economy, and environmental protection, immobilized enzymes have been developed as heterogeneous catalysts to degrade LCB effectively. In this review, applications and mechanisms of LCB‐degrading enzymes are discussed, and the nanomaterials and methods used to immobilize enzymes are also discussed. Finally, the research progress of lignocellulose biodegradation catalyzed by nano‐enzymes was discussed. [ABSTRACT FROM AUTHOR]

In the Anthropocene, plastic pollution is a worldwide concern that must be tackled from different viewpoints, bringing together different areas of science. Microbial transformation of polymers is a broad-spectrum research topic that has become a keystone in the circular economy of fossil-based and biobased plastics. To have an open discussion about these themes, experts in the synthesis of polymers and biodegradation of lignocellulose and plastics convened within the framework of The Transnational Network for Research and Innovation in Microbial Biodiversity, Enzymes Technology and Polymer Science (MENZYPOL-NET), which was recently created by early-stage scientists from Colombia and Germany. In this context, the international workshop "Microbial Synthesis and Degradation of Polymers: Toward a Sustainable Bioeconomy" was held on 27 September 2021 via Zoom. The workshop was divided into two sections, and questions were raised for discussion with panelists and expert guests. Several key points and relevant perspectives were delivered, mainly related to (i) the microbial evolution driven by plastic pollution; (ii) the relevance of and interplay between polymer structure/composition, enzymatic mechanisms, and assessment methods in plastic biodegradation; (iii) the recycling and valorization of plastic waste; (iv) engineered plastic-degrading enzymes; (v) the impact of (micro)plastics on environmental microbiomes; (vi) the isolation of plastic-degrading (PD) microbes and design of PD microbial consortia; and (vii) the synthesis and applications of biobased plastics. Finally, research priorities from these key points were identified within the microbial, enzyme, and polymer sciences. [ABSTRACT FROM AUTHOR]

Xyloglucan is closely associated with cellulose and still retained with some modification in pretreated lignocellulose; however, its influence on lignocellulose biodegradation is less understood. TtGH74 from Thielavia terrestris displayed much higher catalytic activity than previously characterized fungal GH74 xyloglucanases. The carbohydrate-binding module 1 (CBM1) deleted variant (TtGH74ΔCBM) had the same optimum temperature and pH but an elevated thermostability. TtGH74 displayed a high binding affinity on xyloglucan and cellulose, while TtGH74ΔCBM completely lost the adsorption capability on cellulose. Their hydrolysis action alone or in combination with other glycoside hydrolases on the free xyloglucan, xyloglucan-coated phosphoric acid-swollen cellulose or pretreated corn bran and apple pomace was compared. CBM1 might not be essential for the hydrolysis of free xyloglucan but still effective for the associated xyloglucan to an extent. TtGH74 alone or synergistically acting with the CBH1/EG1 mixture was more effective in the hydrolysis of xyloglucan in corn bran, while TtGH74ΔCBM showed relatively higher catalytic activity on apple pomace, indicating that the role and significance of CBM1 are substrate-specific. The degrees of synergy for TtGH74 or TtGH74ΔCBM with the CBH1/EG1 mixture reached 1.22–2.02. The addition of GH10 xylanase in TtGH74 or the TtGH74ΔCBM/CBH1/EG1 mixture further improved the overall hydrolysis efficiency, and the degrees of synergy were up to 1.50–2.16. [ABSTRACT FROM AUTHOR]

Lignocellulosic biomass such as agricultural and forestry waste is the most abundant renewable organic carbon source on earth and can be used to produce source of clean energy such as ethanol. One of the disadvantages of the preparation of ethanol using lignocellulose as raw material is the high cost of production of cellulase. Fungi are capable of effectively degrading lignocellulose and secreting a large amount of cellulase, and have the advantages of ease of preparation, high yield, and full enzyme systems. Therefore, this paper reviews sources of lignocellulose and the biodegradation properties which limit the production of cellulase, proposes micro-organisms capable of degrading lignocellulose and explains the types of cellulase, and the mechanism of action, methods of fermentation optimization, and control are analyzed, and ways to increase the yield of cellulase are described. Finally, research on the effects of inducers on the production of cellulase by fungi is reviewed. The aims of this review are to provide a reference for the efficient production and industrial application of cellulase. [ABSTRACT FROM AUTHOR]

Fungi are ecologically outstanding decomposers of lignocellulose. Fungal lignocellulose degradation is prominent in saprotrophic Ascomycota and Basidiomycota of the subkingdom Dikarya. Despite ascomycetes dominating the Dikarya inventory of aquatic environments, genome and transcriptome data relating to enzymes involved in lignocellulose decay remain limited to terrestrial representatives of these phyla. We sequenced the genome of an exclusively aquatic ascomycete (the aquatic hyphomycete Clavariopsis aquatica), documented the presence of genes for the modification of lignocellulose and its constituents, and compared differential gene expression between C. aquatica cultivated on lignocellulosic and sugar-rich substrates. We identified potential peroxidases, laccases, and cytochrome P450 monooxygenases, several of which were differentially expressed when experimentally grown on different substrates. Additionally, we found indications for the regulation of pathways for cellulose and hemicellulose degradation. Our results suggest that C. aquatica is able to modify lignin to some extent, detoxify aromatic lignin constituents, or both. Such characteristics would be expected to facilitate the use of carbohydrate components of lignocellulose as carbon and energy sources. [ABSTRACT FROM AUTHOR]

The postindustrial era is currently facing two ecological challenges. First, the rise in global temperature, mostly caused by the accumulation of carbon dioxide (CO2) in the atmosphere, and second, the inability of the environment to absorb the waste of human activities. Fungi are valuable levers for both a reduction in CO2 emissions, and the improvement of a circular economy with the optimized valorization of plant waste and biomass. Soil fungi may promote plant growth and thereby increase CO2 assimilation via photosynthesis or, conversely, they may prompt the decomposition of dead organic matter, and thereby contribute to CO2 emissions. The strategies that fungi use to cope with plant-cell-wall polymers and access the saccharides that they use as a carbon source largely rely on the secretion of carbohydrate-active enzymes (CAZymes). In the past few years, comparative genomics and phylogenomics coupled with the functional characterization of CAZymes significantly improved the understanding of their evolution in fungal genomes, providing a framework for the design of nature-inspired enzymatic catalysts. Here, we provide an overview of the diversity of CAZyme enzymatic systems employed by fungi that exhibit different substrate preferences, different ecologies, or belong to different taxonomical groups for lignocellulose degradation. [ABSTRACT FROM AUTHOR]

The recently identified lytic polysaccharide monooxygenases (LPMOs) are important auxiliary proteins which contribute to lignocellulose biodegradation by oxidatively cleaving the glycosidic bonds in cellulose and other polysaccharides. The vast differences in terms of substrate specificity and regioselectivity within LPMOs provide us new possibilities to find promising candidates for the use in enzyme cocktails in biorefinery applications. In this study, a highly xyloglucan active family AA9 lytic polysaccharide monooxygenase Ep LPMO9A was identified from Eupenicillium parvum 4-14. Ep LPMO9A exhibited a mixed C1/C4 oxidative cleavage activity on cellulose and xyloglucan with a broad range of pH stability and good thermal stability at 40 °C. It showed a higher boosting effect on the enzymatic saccharification of complex lignocellulosic substrates associated with xyloglucan than on the lignocellulosic substrates without xyloglucan particularly in low commercial cellulase dosage cases. The oxidative cleavage of xyloglucan by Ep LPMO9A may facilitate to open up the sterical hindrance of cellulose by xyloglucan and thereby increase accessibility for cellulase to lignocellulosic substrates. The discovery of more and more hemicellulose-active LPMOs and their contribution to breaking down the barriers by oxidatively acting on hemicellulose may expand our knowledge for their functions of LPMOs in lignocellulose biodegradation. [ABSTRACT FROM AUTHOR]

The capacity of Pleurotus ostreatus to degrade the lignocellulose of spent coffee grounds (SCG) and its resultant nutrient composition is not yet studied. The study tested four SCG/wheat straw mixtures, containing 0, 33, 67, or 100% SCG. Initial lignin content was higher, and lignin loss was lower in mixtures containing SCG, compared to control revealing lower substrate degradation. Biological yield was negatively correlated with initial lignin content, and positively with the lignin loss from substrates. The nutritional value of mushrooms was improved by a general increase in carbohydrates, a decrease in sodium content with 33% and 67% SCG, and lower fat content with 33% SCG. Polyunsaturated fatty acids of mushrooms (PUFA) increased with 67% SCG; while saturated ones (SFA) increased with 33 and 67% SCG. All mushrooms had a close PUFA/SFA, ranging between 7.4 and 8.1. The study suggests using SCG as a nutritional supplement to the commercial wheat straw. [ABSTRACT FROM AUTHOR]

Rice husk is an abundant agricultural waste generated from rice production, but its application is limited. Considering its complex components, the rice husk was hydrolyzed by different enzymes to enhance its saccharification. In this study, saccharification of the rice husk by cellulase, xylosidase, and xylanase was first investigated. The synergistic effect of LPMO on the above hydrolases and different enzyme combinations in the saccharification process was then explored. Thereafter, the formulation of the enzyme cocktail and the degradation conditions were optimized to obtain the highest saccharification efficiency. The results showed that the optimum enzyme cocktail consists of Celluclast 1.5 L (83.3 mg/g substrate), the key enzymes in the saccharification process, worked with Bp Xyl (20 mg/g substrate), Bp Xyn11 (24 mg/g substrate), and R17L/N25G (4 mg/g substrate). The highest reducing sugar concentration (1.19 mg/mL) was obtained at pH 6.0 and 60 ℃ for 24 h. Fourier transform infrared spectroscopy and scanning electron microscopy were employed to characterize the structural changes in the rice husk after degradation. The results showed that the key chemical bonds in cellulose and hemicellulose were broken. This study illuminated the concept of saccharifying lignocellulose from rice husk using LPMO synergistically assisted combined-hydrolase including cellulase, xylosidase, and xylanase, and provided a theoretical basis for lignocellulose biodegradation. • Synergistic effect of xylanase and xylosidase with cellulase is identified to saccharify rice husk. • LPMO can synergize with the above three hydrolases to saccharify rice husk. • A combination of all four enzymes provided 1.19 mg/mL of reducing sugar production. • The conditions of the degradation process are optimized. [ABSTRACT FROM AUTHOR]

Penicillium purpurogenum is a filamentous fungus, which grows on a variety of natural carbon sources and secretes a large number of enzymes involved in cellulose, hemicelluloses and pectin biodegradation. The purpose of this work has been to identify potential lignocellulolytic enzymes and to compare the secreted enzymes produced when the fungus is grown on sugar beet pulp (rich in cellulose and pectin) and corn cob (rich in cellulose and xylan). Culture supernatants were subjected to two-dimensional nano-liquid chromatography/tandem mass spectrometry. Using MASCOT and a genome-derived protein database, the proteins present in the supernatant were identified. The putative function in the degradation of the polysaccharides was determined using dbCAN software. The results show that there is a good correlation between the polysaccharide composition of the carbon sources and the function of the secreted enzymes: both cultures are rich in cellulases, while sugar beet pulp induces pectinases and corncob, xylanases. The eventual biochemical characterisation of these enzymes will be of value for a better understanding of the biodegradation process performed by the fungus and increase the availability of enzymes for biotechnological methods associated with this process. [ABSTRACT FROM AUTHOR]

Termites are global pests and can cause serious damage to buildings, crops, and plantation forests. The symbiotic intestinal flora plays an important role in the digestion of cellulose and nitrogen in the life of termites. Termites and their symbiotic microbes in the gut form a synergistic system. These organism work together to digest lignocellulose to make the termites grow on nitrogen deficient food. In this paper, the diversity of symbiotic microorganisms in the gut of termites, including protozoan, spirochetes, actinomycetes, fungus and bacteria, and their role in the digestion of lignocellulose and also the biotechnological applications of these symbiotic microorganisms are discussed. The high efficiency lignocellulose degradation systems of symbiotic microbes in termite gut not only provided a new way of biological energy development, but also has immense prospect in the application of cellulase enzymes. In addition, the study on the symbiotic microorganisms in the gut of termites will also provide a new method for the biological control of termites by the endophytic bacteria in the gut of termites. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Cellulose is converted to glucose in yield of 83% by WCl 6 in [BMIM]Cl at 70 °C. • Nature cellulose and lignocelluloses can be degraded by WCl 6 in high yield of TRS. • WCl6 can interact with aldehyde O in cellulose to break the 1,4-glucosidic bond. Abstract Degradation of cellulose to reducing sugar is the key step for the conversion of cellulose to valuable chemicals. Cellulose was degraded by WCl 6 in 1-butyl-3-methyl imidazole chloride at 80 °C and lower. 83% and 85.5% yield of total reducing sugar was gotten at 70 and 80 °C, respectively. Compared with inorganic acid, heteropoly acid, acidic ionic liquid and other metal chlorides, WCl 6 has shown better catalytic performance for degradation of cellulose to reducing sugar. The effect of reaction temperature, reaction time, WCl 6 amount and cellulose concentration were investigated. Degradation of cellulose by WCl 6 in 1-butyl-3-methyl imidazole chloride is a zero reaction. WCl 6 also showed excellent catalytic performance for the degradation of nature cellulose and lignocellulose. Catalyst can be reused at least 5 times without decrease of reducing sugar yield. The mechanism of degradation of WCl 6 was also suggested. [ABSTRACT FROM AUTHOR]

The thermophilic fungus Thielavia terrestris when cultured on cellulose produces a cocktail of thermal hydrolases with potential application in saccharification of lignocellulosic biomass and other biotechnological areas. Glucuronoyl esterases are considered to play a unique role as accessory enzymes in lignocellulosic material biodegradation by cleaving the covalent ester linkage between 4-O-methyl-D-glucuronic acid (MeGlcA) and lignin in lignin-carbohydrate complexes (LCCs). Two glucuronoyl esterases from T. terrestris named TtGE1 and TtGE2 were expressed in Pichia pastoris. Both esterases displayed features of thermophilic enzymes, with the optimal temperature at 45 °C and 55 °C. TtGE1 and TtGE2 exhibited activity towards methyl (4-nitrophenyl β-D-glucopyranosid) uronate (Me-GlcA-pNP) but no catalytic activity to benzyl-D-glucuronate (BnzGlcA), indicating the difference in substrate specificity from previously studied fungal GEs. A substantial increase in the release of monomeric sugars and glucuronic acid from autohydrolysis of corn bran was observed by the supplementing TtGEs into commercial xylanase; the results clearly demonstrated that the TtGEs played a significant role in this degradation process. This research on TtGEs enriches our knowledge of this novel class of fungal GEs. These newly characterized TtGEs could be used as promising accessory enzymes to improve the hydrolysis efficiency of commercial enzymes in saccharification of lignocellulosic materials due to their thermophilic characteristics. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A novel biotechnology combined Fe 3 O 4 NMs and fungal treatment was proposed. • Possible mechanism of enhanced Fenton process was discussed. • Interaction between Fe 3 O 4 NMs and microorganisms was illustrated. • Decrystallization of lignocellulose by fungal treatment was observed. Abstract Nowadays, Nano-biotechnology is emerging to be one of the most promising tools in environmental remediation. In this study, the degradation efficiency of lignocellulose by white-rot fungi was improved by addition of Fe 3 O 4 nanomaterials (NMs) in solid-state fermentation. The highly-ordered cellulose crystalline was demonstrated to be broken down through infrared spectroscopy (FT-IR) and crystallinity index analysis. The decay of fluorescence intensity presented a lower degree of aromatic polycondensation and less conjugated chromophores in lignocellulose. Mechanistic analysis showed that NMs participated in the Fenton reaction and affected lignocellulose biodegradation process by regulating enzyme secretion. Specifically, the time variation curves of hydroxyl radicals and Fe2+ were discussed to illustrate the degradation pattern. The NMs remained stable after the fermentation and were possible to be recycled for the next cycle. All the results support that the synergism of Fe 3 O 4 NMs and white-rot fungi would be a promising research direction in lignocellulose treatment. [ABSTRACT FROM AUTHOR]

Abstract The effect and the response of several trace elements (TE) addition to the anaerobic degradation of key compounds of lignocellulosic biomass were evaluated. Lignin, cellulose and xylose were selected as principal compounds of lignocellulosic biomass. Lignin degradation was only improved by the addition of 1000 mg Fe/L, which allowed an improvement on the methane yield coefficient of 28% compared to control. SEM images from an abiotic assay showed that this effect is more likely related with a chemical effect induced by the Fe solution, instead of an enzymatic response. Pre-treatments focused on breaking the recalcitrant structure of the lignin could be more promising than TE addition for rich lignin-content substrates. Unlike to the response observed with lignin, cellulose showed a clear effect of the TE addition on methane production rate, indicating a higher preponderance of the enzymatic activity compared to the lignin biomethanization. Experiments with xylose resulted in a strong accumulation of volatile fatty acids. TE addition should be adapted to the substrate composition given the different response of each lignocellulosic compound to the different TE addition. Highlights • Lignin, cellulose and xylose were selected to represent the lignocellulose biomass. • Trace elements addition affected differently the biomethanization of each compound. • The addition of 1000 mg Fe/L had an abiotic effect on the structure of the lignin. • Biomethanization of cellulose was significantly affected by Mn addition. [ABSTRACT FROM AUTHOR]

Abstract Symbionts in the gut of termites are expected to be large sources of enzymes involved in lignocellulose degradation, but their biotechnological potential has not been fully explored. In this study, we expressed, purified, and biochemically characterized a glycoside hydrolase family 11 xylanase, NtSymX11, from a symbiotic bacterium of the higher termite, Nasutitermes takasagoensis. NtSymX11 is a multimodular enzyme consisting of a catalytic domain and two tandem carbohydrate-binding modules (CBM36). The pH and temperature optima of NtSymX11 were pH 6.0 and 40 °C, respectively. By comparing the properties of full-length and truncated variants of NtSymX11, it was shown that CBM36 decreases the enzyme stability at acidic pH and high temperature. The main products from xylohexaose and various xylan substrates were X1-X3 xylooligosaccharides. Analysis of kinetic parameters indicated that NtSymX11 displays an outstanding catalytic performance when compared to other reported xylanases, and CBM36 enhances the activity by increasing the affinity to the substrate. Addition of Ca2+ boosted the activity of full-length enzyme, but not the truncated variant lacking the CBM, against the insoluble substrate, suggesting that CBM36 plays a role in the Ca2+-dependent increase of catalytic efficiency. Graphical abstract Image 1 Highlights • A GH11 xylanase, NtSymX11, from a termite symbiotic bacterium was characterized. • NtSymX11 consists of a catalytic domain and two tandem CBM36s. • NtSymX11 displayed a prominent catalytic performance compared to other xylanases. • CBM36 decreased the enzyme stability at acidic pH and high temperature. • CBM36 increased the activity to the insoluble substrate in a Ca2+-dependent manner. [ABSTRACT FROM AUTHOR]

Three experimental groups were designed to study the effects of different exogenous nutrients on a composting process and the degradation extents of cellulose, hemicellulose, and lignin. Hickory shell was the main raw material, and spent mushroom substrate and composted chicken manure were used as exogenous nutrients. The C/N ratios of these groups were adjusted to 34 by using soybean meal. The study results showed that the duration of high-temperature stage of composting was shortened and the maturity of composting products was improved by adding exogenous nutrients. The seed germination index with spent mushroom substrate and composted chicken manure were 112% and 101%. The addition of exogenous nutrients reduced the composting weight loss and increase the degradation extents of cellulose (=64.6%), hemicellulose (=82.4%), and lignin (=64.3%). In particular, the degradation of compost products with composted chicken manure was higher than that of the composting products with the spent mushroom substrate. In the hickory shell composting system, bacteria played a dominant role in the initial and thermophilic phase, and the lignin degradation is related to the quantity of fungi and actinomycetes in composting process. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Actinomycetes were added into straw composting from wheat, rice, corn and soybean. • Bacterial and actinomycetic community composition were analyzed during composting. • Key factor affecting lignocellulose degradation and enzyme activities were discerned. • Inoculation increased 34.3% lignocellulose degradation and 8.3% enzyme activity. • Combined adding inoculants and urea was suggested to improve the inoculation effect. Abstract This study was conducted to assess the effect of thermophilic actinomycetes inoculation on the lignocellulose degradation, enzyme activities and microbial community during different types of straw composting from wheat, rice, corn and soybean. The results showed that actinomycetes inoculation not only changed the structure of actinomycetic and bacterial community but also accelerated the degradation of cellulose, hemicellulose and lignin and increased the key enzymes activities including CMCase, Xylanase, manganese peroxidase, lignin peroxidase and laccase during composting particularly from wheat straw and rice straw. The key enzyme and physiochemical parameters which affected organic fractions degradation have been identified by redundancy analysis. The combined application of actinomycete inoculation and urea addition as a source of nitrogen was suggested to regulate the key enzyme activities and lignocellulose degradation, which lays a foundation for effectively managing organic wastes from different types of crop straws by composting. [ABSTRACT FROM AUTHOR]

Abstract The characteristics of bio-oil produced from biomass pyrolysis can be improved by co-feeding waste materials. In this work, co-pyrolysis of lignocellulosic biomass with six different waste plastics (waste tyre (WT), polylactic acid (PLA), polystyrene (PS), polyethylene terephthalate (PET), polypropylene (PP) and high density polyethylene (HDPE)) were conducted in a thermogravimetric analyser to study thermal decomposition of the mixtures. The distributed activation energy model (DAEM) was applied to pure feedstocks at 5 and 10 °C/min heating rates to fit the kinetic parameters. The model was used to simulate the co-pyrolysis of biomass/plastic mixtures assuming additive effect of components at different weight proportions and heating rates. Profiles of the fraction of mass remaining for mixtures at 100 °C/min were reproduced with a remarkable agreement. Discrepancies between the experimental and calculated profiles were considered as a measure of the extent of interactions occurring in the co-pyrolysis. Projections of the behaviour of mixtures under flash pyrolysis conditions were performed to study important aspects of the process, such as radical interactions and optimum working temperature. Highlights • The Distributed Activation Energy Model was applied to co-pyrolysis. • Mixtures of lignocellulosic biomass and plastic wastes were studied. • Different proportions of components and heating rates were successfully simulated. • Deviations of simulations from experiments were ascribed to interactions of solids. • Interactions depend on the nature and proportion of plastics and the heating rate. [ABSTRACT FROM AUTHOR]

Abstract The efficiency of enzymatic hydrolysis is reduced by the naturally recalcitrant complex polymers comprising lignocellulose. Increasing enzymatic conversion, which the complex macromolecules converted into simpler molecules, is still had to be overcome. High hydrostatic pressure (HHP), an emerging technology, is expected to ameliorate the situation. The effects of enzymatic hydrolysis after HHP pretreatment on pumpkin lignocellulose were studied and compared with hydrothermal and alkaline pretreatment. Further investigation was performed to evaluate the effect of enzymatic hydrolysis of pumpkin combined with HHP treatment. The samples underwent HHP treatment simultaneously exhibited overall better performance in enzymatic hydrolysis than the untreated. The highest glucose yield of 91.2% and xylose yield of 84.2% was achieved when 400 MPa HHP with high enzyme loading was applied. HHP exerted positive effects on enzyme-substrate interactions during the enzymatic hydrolysis of lignocellulose, which implied that HHP technology combined with enzymatic hydrolysis could be used to pretreat pumpkin pomace. Highlights • Cellulose and hemicellulose removal significantly increased after hydrothermal and alkaline pretreatment. • The highest yields of glucose and xulose were achieved at 400 MPa with high enzyme loading. • High hydrostatic pressure exerted positive effects on enzyme-lignocellulose complex interactions. • The method of high hydrostatic pressure was established on the conversion of lignocellulose. [ABSTRACT FROM AUTHOR]

The generation of a complex microbial consortium is a promising approach for efficient biomass decomposition. An anaerobic thermophilic alkaliphilic microbial consortium with efficient degradation ability was screened from bovine manure compost using non-pretreated milling corn stover (CS) and rice straw (RS). A stable microbial consortium ISHI-3 with high degradation ability for CS and RS was isolated by the roll tube technique. ISHI-3 comprised Herbivorax saccincola and bacteria belonging to the classes Pelotomaculum, Tepidanaerobacter , and Tepidimicrobium , as determined by DGGE of the PCR-generated 16S rRNA genes. Furthermore, metagenomics analysis using a 16S rRNA library was carried out to determine the bacterial distribution during degradation of CS and RS. H. saccincola and bacteria belonging to Pelotomaculum were relatively abundant in the beginning to middle periods of culture with CS and RS whereas bacteria belonging to Tepidanaerobacter and Tepidimicrobium gradually increased in the population during the later stages. To understand the role of non-cellulolytic bacteria in the consortium, novel strains ET1 and GL4, which were most closely related to Tepidimicrobium ferriphilum and Tepidanaerobacter acetatoxydans , were isolated from ISHI-3. Based on their carbon source usage, morphology, and phylogenetic analysis, we propose that strains ET1 and GL4 should be classified as a novel genus or species. Bacteria ET1 and GL4 can utilize different organic compounds as carbon and energy sources such as organic acids, alcohols, sugars, and amino acids, showing a preference for organic acids and alcohols rather than sugars such as glucose and cellobiose. These results indicated that ET1 and GL4 help to accelerate efficient lignocellulose degradation of H. saccincola . [ABSTRACT FROM AUTHOR]

Glucuronoyl esterases (GEs) belonging to the carbohydrate esterase family 15 (CE15) are involved in microbial degradation of lignocellulosic plant materials. GEs are capable of degrading complex polymers of lignin and hemicellulose cleaving ester bonds between glucuronic acid residues in xylan and lignin alcohols. GEs promote separation of lignin, hemicellulose and cellulose which is crucial for efficient utilization of biomass as an energy source and feedstock for further processing into products or chemicals. Genes encoding GEs are found in both fungi and bacteria, but, so far, bacterial GEs are essentially unexplored, and despite being discovered >10 years ago, only a limited number of GEs have been characterized. The first laboratory scale example of improved xylose and glucuronic acid release by the synergistic action of GE with cellulolytic enzymes was only reported recently (improved C5 sugar and glucuronic acid yields) and, until now, not much is known about their biotechnology potential. In this review, we discuss the diversity, structure and properties of microbial GEs and consider the status of their action on natural substrates and in biological systems in relation to their future industrial use. [ABSTRACT FROM AUTHOR]

Abstract Penicillium purpurogenum grows on a variety of natural carbon sources and secretes to the medium a large number of enzymes that degrade the polysaccharides present in lignocellulose. In this work, the gene coding for a novel xylanase (XynC) belonging to family 30 of the glycoside hydrolases (GH), has been identified in the genome of the fungus. The enzyme has been expressed in Pichia pastoris and characterized. The mature XynC has 454 amino acid residues and a calculated molecular weight of 49 240. The purified protein shows a molecular weight of 67 000, and it is partially deglycosylated using EndoH. Its pH optimum is in the range of 3–5, and the optimal temperature is 45 °C. It is active on both arabinoxylan and glucuronoxylan, similarly to other fungal GH 30 xylanases. It liberates a set of oligosaccharides, which have been detected by thin-layer chromatography, thus indicating that it is an endo-acting xylanase. It hydrolyzes xylooligosaccharides, releasing mainly xylobiose, in contrast to other fungal GH family 30 enzymes which generate chiefly xylose. Highest sequence identity to a characterized family 30 xylanase is found with the enzyme from the fungus Bispora sp (53%). This is the first GH 30 xylanase described from a Penicillium. Graphical abstract Thin layer chromatography of the hydrolysis products generated by XynC when acting on xylo-oligosaccharides. Lane 1: xylose. Lane 2: xylose + XynC. Lane 3: xylobiose. Lane 4: xylobiose + XynC. Lane 5: xylotriose. Lane 6: xylotriose + XynC. Lane 7: xylotetraose. Lane 8: xylotetraose + Xyn C. Lane 9: xylopentaose. Lane 10: xylopentaose + XynC. Lane 11: xylohexaose. Lane 12, xylohexaose + XynC. Image 1 Highlights • The gene of a family 30 xylanase was found in the genome of Penicillium purpurogenum. • The enzyme (XynC) was heterologously expressed in Pichia pastoris. • XynC is active on a variety of xylans and on xylooligosaccharides. • In contrast to other GH 30 xylanases, it liberates xylobiose in preference to xylose. [ABSTRACT FROM AUTHOR]

Overcoming recalcitrance of lignin has motivated bioprospecting of high-yielding enzymes from environmental ligninolytic microorganisms associated with lignocellulose degrading-systems. Here, we performed isolation of 21 ligninolytic strains belonging to the genus Klebsiella spp., driven by the presence of lignin in the media. The fastest-growing strains (FP10-5.23, FP10-5.22 and P3TM1) reached the stationary phase in approximately 24 h, in the media containing lignin as the main carbon source. The strains showed biochemical evidence of ligninolytic potential in liquid- and solid media-converting dyes, which the molecular structures are similar to lignin fragments. In liquid medium, higher levels of dye decolorization was observed for P3TM.1 in the presence of methylene blue, reaching 98% decolorization in 48 h. The highest index values (1.25) were found for isolates P3TM.1 and FP10-5.23, in the presence of toluidine blue. The genomic analysis revealed the presence of more than 20 genes associated with known prokaryotic lignin-degrading systems. Identification of peroxidases (lignin peroxidase—LiP, dye-decolorizing peroxidase—DyP, manganese peroxidase—MnP) and auxiliary activities (AA2, AA3, AA6 and AA10 families) among the genetic repertoire suggest the ability to produce extracellular enzymes able to attack phenolic and non-phenolic lignin structures. Our results suggest that the Klebsiella spp. associated with fresh water and soil may play important role in the cycling of recalcitrant molecules in the Caatinga (desert-like Brazilian biome), and represent a potential source of lignin-degrading enzymes with biotechnological applications. [ABSTRACT FROM AUTHOR]

Biological pretreatment with novel isolated microbial pure culture was utilised to pretreat water hyacinth to enhance its solubilisation followed by biogas production. Lignocellulose degrading bacterial strains isolated from soil ( Bordetella muralis VKVVG5 ) (UN3d2), the gut of silverfish ( Citrobacter werkmanii VKVVG4 ) (SFa2) and millipede ( Paenibacillus sp. VKVVG1 ) (BrB2) were employed to optimise the ideal bacterial strain illustrating accelerated hydrolysis of water hyacinth. Citrobacter werkmanii VKVVG4 pretreatment of water hyacinth with an optimum dosage of 10 9  CFU/mL and time of 4 days helped in achieving the highest solubilisation of 33.3%. Biochemical methane potential (BMP) test was conducted between untreated and Citrobacter werkmanii VKVVG4 pretreated water hyacinth. Biochemical methane potential (BMP) test of pretreated water hyacinth illustrated faster start up period than the untreated water hyacinth. Citrobacter werkmanii VKVVG4 (SFa2) pretreated water hyacinth illustrated a cumulative biogas production of 3737 ± 21 mL whereas untreated water hyacinth illustrated a cumulative biogas production of 3038 ± 13 mL on the 50 th day. Scaled up batch (20 L) study demonstrated a three times increase in the cumulative biogas generation of the microbial pretreated water hyacinth than the untreated water hyacinth. [ABSTRACT FROM AUTHOR]

The mechanisms by which specific anaerobic microorganisms remain firmly attached to lignocellulosic material, allowing them to efficiently decompose organic matter, have yet to be elucidated. To circumvent this issue, microbiomes collected from anaerobic digesters treating pig manure and meadow grass were fractionated to separate the planktonic microbes from those adhered to lignocellulosic substrate. Assembly of shotgun reads, followed by a binning process, recovered 151 population genomes, 80 out of which were completely new and were not previously deposited in any database. Genome coverage allowed the identification of microbial spatial distribution in the engineered ecosystem. Moreover, a composite bioinformatic analysis using multiple databases for functional annotation revealed that uncultured members of the Bacteroidetes and Firmicutes follow diverse metabolic strategies for polysaccharide degradation. The structure of cellulosome in Firmicutes species can differ depending on the number and functional roles of carbohydrate-binding modules. In contrast, members of the Bacteroidetes are able to adhere to and degrade lignocellulose due to the presence of multiple carbohydrate-binding family 6 modules in beta-xylosidase and endoglucanase proteins or S-layer homology modules in unknown proteins. This study combines the concept of variability in spatial distribution with genome-centric metagenomics, allowing a functional and taxonomical exploration of the biogas microbiome. IMPORTANCE: This work contributes new knowledge about lignocellulose degradation in engineered ecosystems. Specifically, the combination of the spatial distribution of uncultured microbes with genome-centric metagenomics provides novel insights into the metabolic properties of planktonic and firmly attached to plant biomass bacteria. Moreover, the knowledge obtained in this study enabled us to understand the diverse metabolic strategies for polysaccharide degradation in different species of Bacteroidetes and Clostridiales. Even though structural elements of cellulosome were restricted to Clostridiales species, our study identified a putative mechanism in Bacteroidetes species for biomass decomposition, which is based on a gene cluster responsible for cellulose degradation, disaccharide cleavage to glucose, and transport to cytoplasm. [ABSTRACT FROM AUTHOR]

Abstract Anaerobic digestion is a feasible method for vinegar residue disposal. However, its treatment efficiency is limited significantly by the low degradation of lignocellulose. In this study, a stable and efficient anaerobic digestion system for vinegar residue was constructed. The continuous solid-state reactor achieved a specific production of 418 mL·g-1 VS biogas and 223 mL·g-1 VS methane at a high organic loading rate (OLR) of 5.83 g VS ·(L·d)−1. The stable degradation of lignocellulose between 39.5% and 36.4% was key factor for stable anaerobic digestion at high OLR. This stability under optimum OLR was due to the increase in the degradation of hemicellulose, which compensated for the loss of lignocellulose degradation. The enrichment of microorganism related to lignocellulose hydrolysis and the stable microbial community structure ensured efficient anaerobic digestion under high OLR condition. Digestion efficiency can be further improved mainly by increasing cellulose degradation. This investigation provided the theoretical basis for practical application of this digestion system for solid vinegar residue treatment. Graphical abstract Image 1 Highlights • A stable efficient anaerobic digestion system via vinegar residue was constructed. • Optimum organic loading rate reached up to 5.83g VS ·(L·d)−1. • Increasing of hemicellulose hydrolysis rate stabilized system efficiency. • Potential improvement on efficiency was depended on cellulose released and hydrolysis. • Growth and uniform distribution of hydrolysis microbes ensured system efficiency. [ABSTRACT FROM AUTHOR]

Biomass hydrolysis constitutes a bottleneck for the biotransformation of lignocellulosic residues into bioethanol and high-value products. The efficient deconstruction of polysaccharides to fermentable sugars requires multiple enzymes acting concertedly. GH43 β-xylosidases are among the most interesting enzymes involved in hemicellulose deconstruction into xylose. In this work, the structural and functional properties of β-xylosidase EcXyl43 from Enterobacter sp. were thoroughly characterized. Molecular modeling suggested a 3D structure formed by a conserved N-terminal catalytic domain linked to an ancillary C-terminal domain. Both domains resulted essential for enzymatic activity, and the role of critical residues, from the catalytic and the ancillary modules, was confirmed by mutagenesis. EcXyl43 presented β-xylosidase activity towards natural and artificial substrates while arabinofuranosidase activity was only detected on nitrophenyl α-L-arabinofuranoside (pNPA). It hydrolyzed xylobiose and purified xylooligosaccharides (XOS), up to degree of polymerization 6, with higher activity towards longer XOS. Low levels of activity on commercial xylan were also observed, mainly on the soluble fraction. The addition of EcXyl43 to GH10 and GH11 endoxylanases increased the release of xylose from xylan and pre-treated wheat straw. Additionally, EcXyl43 exhibited high efficiency and thermal stability under its optimal conditions (40 °C, pH 6.5), with a half-life of 58 h. Therefore, this enzyme could be a suitable additive for hemicellulases in long-term hydrolysis reactions. Because of its moderate inhibition by monomeric sugars but its high inhibition by ethanol, EcXyl43 could be particularly more useful in separate hydrolysis and fermentation (SHF) than in simultaneous saccharification and co-fermentation (SSCF) or consolidated bioprocessing (CBP). [ABSTRACT FROM AUTHOR]

Enriched microbial communities, obtained from environmental samples through selective processes, can effectively contribute to lignocellulose degradation. Unfortunately, fully controlled industrial degradation processes are difficult to reach given the intrinsically dynamic nature and complexity of the microbial communities, composed of a large number of culturable and unculturable species. The use of less complex but equally effective microbial consortia could improve their applications by allowing for more controlled industrial processes. Here, we combined ecological theory and enrichment principles to develop an effective lignocellulose-degrading minimal active microbial Consortia (MAMC). Following an enrichment of soil bacteria capable of degrading lignocellulose material from sugarcane origin, we applied a reductive-screening approach based on molecular phenotyping, identification, and metabolic characterization to obtain a selection of 18 lignocellulose-degrading strains representing four metabolic functional groups. We then generated 65 compositional replicates of MAMC containing five species each, which vary in the number of functional groups, metabolic potential, and degradation capacity. The characterization of the MAMC according to their degradation capacities and functional diversity measurements revealed that functional diversity positively correlated with the degradation of the most complex lignocellulosic fraction (lignin), indicating the importance of metabolic complementarity, whereas cellulose and hemicellulose degradation were either negatively or not affected by functional diversity. The screening method described here successfully led to the selection of effective MAMC, whose degradation potential reached up 96.5% of the degradation rates when all 18 species were present. A total of seven assembled synthetic communities were identified as the most effective MAMC. A consortium containing Stenotrophomonas maltophilia, Paenibacillus sp., Microbacterium sp., Chryseobacterium taiwanense, and Brevundimonas sp. was found to be the most effective degrading synthetic community. [ABSTRACT FROM AUTHOR]

This research aims to provide a better knowledge of the thermal decomposition of the olive cake as well as this lignocellulosic material loaded, in a previous stage of biosorption, with heavy metals for its use in processes of energy recovery. Firstly, isolation of constituents of the olive cake was carried out. Then, experiments were performed by thermogravimetric analysis (TGA) and differential thermogravimetry (DTG) under inert and oxidative atmosphere at a heating rate of 15 K/min for each isolated fraction. Next, adequate reactions schemes were proposed to find kinetic parameters. Validation of these schemes were verified by the goodness of fitting between experimental and simulated data. Also, some important combustion characteristics such as ignition and burnout temperatures were determined. With regard to the effect of metals, cadmium, copper, chromium, nickel and lead present in metal-loaded olive cake did not modify values of kinetic parameters which described the thermal decomposition processes. [ABSTRACT FROM AUTHOR]

The suitability of three local lignocellulosic wastes i.e. almond shell (AS), rice husk (RH) and seagrass (SG) as fillers in PHB/Fiber composites applications has been studied. PHB/Fiber composites with 10 phr and 20 phr fiber content were prepared by melt blending. The influence of the fiber type (size, morphology and origin) and content on the morphological, mechanical and thermal properties of the as obtained composites has been assessed. To evaluate the potential use in food packaging applications, the barrier performance to water, thermoforming ability and disintegration in controlled composting conditions of the composites were also studied. All the fibers have demonstrated to be apt for their use as fillers in PHB/Fiber composites, showing a reinforcing effect without affecting the crystallinity and the disintegration rate of PHB. The thermal stability and the water barrier performance of the composites were reduced by the presence of the fibers. Nevertheless, the addition of AS resulted in the best balance of properties, in terms of permeability and mechanical properties, finding an enhancement of the thermoforming ability of PHB when 10 phr of AS was added. [ABSTRACT FROM AUTHOR]

The thermal properties of cellulose, hemicellulose and lignin can be utilized to improve the characteristics of pyrolysis liquids. In this study, a concept of stepwise pyrolysis to fractionate the liquid based on the thermal properties of the biomass constituents was investigated. Lignocellulosic biomass was thermally treated in two steps: 200–300 °C followed by 550 °C. Derived liquids were studied for GC/MS analysis, water content, acid concentration and a solvent extraction method. Pyrolytic liquid derived from 550 °C after treatment at lower temperatures have a higher relative composition of phenolic compounds compared to one-step pyrolysis (increased from 58 to 90% of GC/MS peak area). Also, compounds known to promote aging, such as acids and carbonyl compounds, are derived at lower temperatures which may suppress aging in the liquid derived downstream at 550 °C. For liquids derived at 550 °C, the total acid number was reduced from 125 in one-step treatment to 14 in two-step treatment. Overall, no significant difference in the total liquid yield (sum of the liquids derived in separated treatments) nor any variations in their collective composition compared to one-step treatment at 550 °C was observed, i.e. stepwise pyrolysis can be utilized for direct fractionation of pyrolytic vapors. [ABSTRACT FROM AUTHOR]

Previously identified twelve plant cell wall degradation-associated genes of the white rot fungus Phlebia radiata were studied by RT-qPCR in semi-aerobic solid-state cultures on lignocellulose waste material, and on glucose-containing reference medium. Wood-decay-involved enzyme activities and ethanol production were followed to elucidate both the degradative and fermentative processes. On the waste lignocellulose substrate, P. radiata carbohydrate-active enzyme (CAZy) genes encoding cellulolytic and hemicellulolytic activities were significantly upregulated whereas genes involved in lignin modification displayed a more complex response. Two lignin peroxidase genes were differentially expressed on waste lignocellulose compared to glucose medium, whereas three manganese peroxidase-encoding genes were less affected. On the contrary, highly significant difference was noticed for three cellulolytic genes (cbhI_1, eg1, bgl1) with higher expression levels on the lignocellulose substrate than on glucose. This indicates expression of the wood-attacking degradative enzyme system by the fungus also on the recycled, waste core board material. During the second week of cultivation, ethanol production increased on the core board to 0.24 g/L, and extracellular activities against cellulose, xylan, and lignin were detected. Sugar release from the solid lignocellulose resulted with concomitant accumulation of ethanol as fermentation product. Our findings confirm that the fungus activates its white rot decay system also on industrially processed lignocellulose adopted as growth substrate, and under semi-aerobic cultivation conditions. Thus, P. radiata is a good candidate for lignocellulose-based renewable biotechnology to make biofuels and biocompounds from materials with less value for recycling or manufacturing. [ABSTRACT FROM AUTHOR]

Abstract: The additional costs required for the pre‐treatment of lignocellulosic bio‐mass prior to enzymatic hydrolysis have limited the commercial implementation of lignocellulosic bio‐chemical production. The use of acidic mine drainage (AMD) water as an acid source for lignocellulosic pre‐treatment has recently been investigated. Large quantities of AMD in South Africa suggest that AMD can be obtained cheaply, thus reducing the cost and increasing the potential of lignocellulosic bio‐chemicals. Acidic mine drainage could undergo further remediation using sulfate‐reducing bacteria (SRB) so that the water is suitable for release. The feasibility of such a system could be greatly improved if this process were to be incorporated within a bio‐refinery, such that all fractions of the bio‐mass are used to produce multiple products. This paper investigates such a bio‐refinery system, and evaluates the different options based on the bio‐refinery complexity profile (BCP). Due to the abundance of grass in the regions where AMD is generated, this was found to be the most suitable feedstock. The most feasible bio‐refinery option was found to produce ethanol through fermentation of C6 sugars, although it is recommended that further investigation be conducted into additional high‐value bio‐chemicals from the C6 sugar platform. C5 sugars released in pre‐treatment could be used as a substrate by SRB for AMD remediation. Gasification and direct combustion of lignin had similar BCPs and thus further investigation is required to determine the preferred path. Similarly, further investigation is required for the best processing route for distillery silage. © 2018 Society of Chemical Industry and John Wiley & Sons, Ltd [ABSTRACT FROM AUTHOR]

Achieving low cost and high efficiency lignocellulose deconstruction is a critical step towards widespread adoption of lignocellulosic biofuels. Certain ionic liquid (IL)-based pretreatment processes effectively reduce recalcitrance of lignocellulose to enzymatic degradation but require either costly separations following pretreatment or novel IL compatible processes to mitigate downstream toxicity. Here we demonstrate at benchtop and pilot bioreactor scales a separation-free, intensified process for IL pretreatment, saccharification, and fermentation of sorghum biomass to produce the sesquiterpene bisabolene, a precursor to the renewable diesel and jet fuel bisabolane. The deconstruction process employs the IL cholinium lysinate ([Ch][Lys]), followed by enzymatic saccharification with the commercial enzyme cocktails Cellic CTec2 and HTec2. Glucose yields above 80% and xylose yields above 60% are observed at all scales tested. Unfiltered hydrolysate is fermented directly by Rhodosporidium toruloides– with glucose, xylose, acetate and lactate fully consumed during fermentation at all scales tested. Bisabolene titers improved with scale from 1.3 g L−1 in 30 mL shake flasks to 2.2 g L−1 in 20 L fermentation. The combined process enables conversion of saccharified IL-pretreated biomass directly to advanced biofuels with no separations or washing, minimal additions to facilitate fermentation, no loss of performance due to IL toxicity, and simplified fuel recovery via phase separation. This study is the first to demonstrate a separation-free IL based process for conversion of biomass to an advanced biofuel and is the first to demonstrate full consumption of glucose, xylose, acetate, and lactic acid in the presence of [Ch][Lys]. [ABSTRACT FROM AUTHOR]

The hydrodeoxygenation (HDO) reaction is critical to the upgrading of lignocellulosic biomass into valuable fuels and chemicals. Many transition metal carbide (TMC) catalysts have been shown to be highly selective toward the C–O/C=O bond scission, which makes them promising catalysts for the HDO reaction. This review summarizes the reaction pathways of linear and ring-containing biomass-derived oxygenates over TMC model surfaces and powder catalysts, followed by a discussion on the effect of reaction conditions on reaction pathways. The combination of first principles calculations, model surface experiments, and parallel reactor studies demonstrates the feasibility of using model surface science studies to guide the rational design of efficient catalysts for the upgrading of lignocellulosic biomass derivatives. General trends and future research directions of using TMC catalysts for HDO are also discussed. [ABSTRACT FROM AUTHOR]

Ganoderma lucidum is a medicinal mushroom that is well known for its ability to enhance human health, and products made from this fungus have been highly profitable. The substrate-degrading ability of G. lucidum could be related to its growth. CAZy proteins were more abundant in its genome than in the other white rot fungi models. Among these CAZy proteins, changes in lignocellulolytic enzymes during growth have not been well studied. Using genomic, transcriptomic and secretomic analyses, this study focuses on the lignocellulolytic enzymes of G. lucidum strain G0119 to determine which of these degradative enzymes contribute to its growth. From the genome sequencing data, genes belonging to CAZy protein families, especially genes involved in lignocellulose degradation, were investigated. The gene expression, protein abundance and enzymatic activity of lignocellulolytic enzymes in mycelia over a growth cycle were analysed. The overall expression cellulase was higher than that of hemicellulase and lignin-modifying enzymes, particularly during the development of fruiting bodies. The cellulase and hemicellulase abundances and activities increased after the fruiting bodies matured, when basidiospores were produced in massive quantities till the end of the growth cycle. Additionally, the protein abundances of the lignin-modifying enzymes and the expression of their corresponding genes, including laccases and lignin-degrading heme peroxidases, were highest when the mycelia fully spread in the compost bag. Type I cellobiohydrolase was observed to be the most abundant extracellular lignocellulolytic enzyme produced by the G. lucidum strain G0119. The AA2 family haem peroxidases were the dominant lignin-modifying enzyme expressed during the mycelial growth phase, and several laccases might play roles during the formation of the primordium. This study provides insight into the changes in the lignocellulose degradation ability of G. lucidum during its growth and will facilitate the discovery of new approaches to accelerate the growth of G. lucidum in culture. [ABSTRACT FROM AUTHOR]

In this study, the gene fusion of endoglucanase (EG, one of cellulases) from Teleogryllus emma and xylanase (Xyn, one of hemicellulases) from Thermomyces lanuginosus was constructed to generate a fusion enzyme (EG-M-Xyn). Through the expression and purification by ultrafiltration and size-exclusion chromatography, the purified EG-M-Xyn had a molecular weight of 75.5 kDa and exhibited the specific activity of CMCase and xylanase as 306.8 U/mg and 1227.3 U/mg, respectively. The K m values (CMC and beechwood xylan) were 6.8 and 60.6 mg mL −1 while catalytic efficiency ( k cat / K m ) values of CMCase and xylanase were 3280 and 38,797 min −1  mg −1  mL, respectively. EG-M-Xyn exerted great properties for its great potential in improving the enzymatic hydrolysis of lignocellulosics to produce fermentable sugars. First, EG-M-Xyn showed mild reaction pH and temperature of 5.5 and 50 °C, respectively. Secondly, EG-M-Xyn exhibited great heat tolerance of T 1/2 values of 173 (CMCase) and 693 min (xylanase). Lastly and most importantly, application of EG-M-Xyn in combination with Ctec2 (commercial enzyme) in the saccharification led to a 10–20% net increase in fermentable sugars liberated from pretreated rice straw in comparison to the Ctec2 alone group. In conclusion, EG-M-Xyn had great potential in generating fermentable sugars from renewable agro-residues for biofuel and fine chemical industry. [ABSTRACT FROM AUTHOR]

In this study, the rate of xylan hydrolysis was investigated. The hydrolysis of tulip poplar was conducted in subcritical water from 180 to 220 °C for 1–240 min. An equation for estimating the hydrolysis of ether bonds in both xylan and xylooligosaccharide from the yield of xylan and xylooligosaccharide was derived, and the rate constant of ether bond hydrolysis was calculated using the derived equation. It was found that our kinetic study can be applied to subcritical water treatment of various lignocellulosic biomass. In addition, linearity between the apparent activation energy and the logarithmic value of the apparent pre-exponential factor was observed. An equation for the apparent reaction rate constant was derived by introducing a factor, α, that reflects the changes in the reaction rate arising from various factors. [ABSTRACT FROM AUTHOR]

Oil palm trunk (OPT) is one of the most promising lignocellulosic bioresources. To develop effective biodegradation, thermophilic, anaerobic microorganisms were screened from bovine manure compost using fibrillated OPT (f-OPT) pretreated by wet disk milling as the substrate. One thermophilic, anaerobic bacterium, strain CL-2, whose 16S rDNA gene has 98.6% sequence identity with that of Caldicoprobacter faecale DSM 20678 T , exhibited high degradation activity (32.7% reduction in total dry solids of f-OPT). Strain CL-2 did not use cellulose as a carbon source, but used hemicelluloses such as xylan, arabinoxylan, starch and pectin at 70 °C. Phylogenetic and morphologic analyses and the polysaccharide use suggest that CL-2 may be classified as a novel species of Caldicoprobacter , named Caldicoprobacter sp. CL-2. To characterize enzymatic activities of CL-2, extracellular enzymes were prepared from culture broth using beechwood xylan as the carbon source. The extracellular enzymes showed high xylanase activity, but low cellulase activity, suggesting that f-OPT degradation may depend on xylanase activity. To understand the xylanase system of CL-2, a major xylanase was cloned and characterized. The xylanase ( Cal Xyn11A) had a modular structure consisting of a glycoside hydrolase (GH) family-11 domain and a family 36 carbohydrate-binding module. Cal Xyn11A did not show f-OPT degradation activity, but a strong synergistic effect was observed when Cal Xyn11A was added to the extracellular enzyme preparation. These results indicate that, rather than working alone, Cal Xyn11A has an important role in enhancing total lignocellulose degradation activity by cooperation with other GHs. [ABSTRACT FROM AUTHOR]

Alkaline pretreatment of lignocellulosic biomass is an approach to enhance the susceptibility of the biomass that is subsequently converted into fermentable sugars. The efficacy of the sodium hydroxide pretreatment of rice straw RD41 was evaluated in terms of total solid removal, lignin removal, glucan recovery, and glucan conversion yields. The pretreatment conditions were 50, 60, 70, 80, and 100 °C, and each temperature kept for 1 to 5 h. The effect of pretreatment temperatures was more pronounced than that of the pretreatment times. The elevated temperatures caused higher total solid removal and lignin removal. The highest total solid removal (52.5 to 55.8 %) was found in the pretreatment at 100 °C. At this temperature, the highest lignin removal (~87 %) could be obtained regardless of the residence times of the pretreatment. Most of the glucan (~80 to 100 %) was preserved in the pretreated rice straw. Lower temperatures (50 and 60 °C) favored higher glucan preservation (> 90 %) in the pretreated solids. Glucan conversion of the 3 h pretreatment time samples of each pretreatment temperature revealed that more than 80 % of glucan conversion could be accounted for in samples pretreated at 70 to 100 °C within 24 h of saccharification. The lower temperatures required a prolonged pretreatment time to reach a higher glucan conversion (~90 %), as found in the 50 °C, 5 h pretreated rice straw. The optimal conditions of this simple method are economically feasible, and can be applied to testing the reactivity of herbaceous lignocellulose in future research. [ABSTRACT FROM AUTHOR]

The microbial degradation of plant-derived compounds under salinity stress remains largely underexplored. The pretreatment of lignocellulose material, which is often needed to improve the production of lignocellulose monomers, leads to high salt levels, generating a saline environment that raises technical considerations that influence subsequent downstream processes. Here, we constructed halotolerant lignocellulose degrading microbial consortia by enriching a salt marsh soil microbiome on a recalcitrant carbon and energy source, i.e., wheat straw. The consortia were obtained after six cycles of growth on fresh substrate (adaptation phase), which was followed by four cycles on pre-digested (highly-recalcitrant) substrate (stabilization phase). The data indicated that typical salt-tolerant bacteria made up a large part of the selected consortia. These were “trained” to progressively perform better on fresh substrate, but a shift was observed when highly recalcitrant substrate was used. The most dominant bacteria in the consortia were Joostella marina, Flavobacterium beibuense, Algoriphagus ratkowskyi, Pseudomonas putida, and Halomonas meridiana. Interestingly, fungi were sparsely present and negatively affected by the change in the substrate composition. Sarocladium strictum was the single fungal strain recovered at the end of the adaptation phase, whereas it was deselected by the presence of recalcitrant substrate. Consortia selected in the latter substrate presented higher cellulose and lignin degradation than consortia selected on fresh substrate, indicating a specialization in transforming the recalcitrant regions of the substrate. Moreover, our results indicate that bacteria have a prime role in the degradation of recalcitrant lignocellulose under saline conditions, as compared to fungi. The final consortia constitute an interesting source of lignocellulolytic haloenzymes that can be used to increase the efficiency of the degradation process, while decreasing the associated costs. [ABSTRACT FROM AUTHOR]

To maintain our society’s sustainability with respect to people, prosperity, and the planet, we must produce liquid transportation fuels such as bioethanol on the renewable basis at a competitive price to petroleum-based fuels. The major challenges to commercialize cellulosic biofuels are low fermentation efficiency, low ethanol titer, and lack of technology to fully utilize the byproduct from bioconversion process such as lignin which has been underutilized. To overcome these technical barriers, we have proposed a novel design to fully utilize each component of lignocellulosic biomass for biofuels and bio-chemicals production, which involves green technologies such as hydrothermal and organosolv pretreatments to produce a cellulose-rich solid with good recovery of clean lignin after solvent recycling for improvement of plant protein-based adhesives as well as xylose remained in the aqueous phase for furfural upgradation. The focus of this study, as a part of the whole biorefinery concept, is to develop modified simultaneous saccharification and fermentation (mSSF) to enhance ethanol titers and yields, which combines the advantages of both separate hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF) via unique decantation process. The mSSF achieved higher ethanol concentration of 58.5 g/L and ethanol yield of 83.5% as compared to the traditional SSF process (49.9 g/L and 71.1%) at the biomass loadings of 20% (w/v). The mSSF also enabled higher ethanol titers of 72.3 g/L at higher loadings of 30% (w/v) with yields of 70.0%. As compared to published high-gravity fermentation, ethanol concentration of 72.3 g/L achieved in this study was the highest one in the lab-scale process, which proved that the proposed mSSF was an effective process to increase ethanol titers without sacrificing ethanol yields. The improved ethanol titers and yields would significantly lower the distillation cost and accelerate the commercialization of cellulosic biofuel production. [ABSTRACT FROM AUTHOR]

Summary: Lignocellulose degradation by microbes plays a central role in global carbon cycling, human gut metabolism and renewable energy technologies. While considerable effort has been put into understanding the biochemical aspects of lignocellulose degradation, much less work has been done to understand how these enzymes work in an in vivo context. Here, we report a systems level study of xylan degradation in the saprophytic bacterium Cellvibrio japonicus. Transcriptome analysis indicated seven genes that encode carbohydrate active enzymes were up‐regulated during growth with xylan containing media. In‐frame deletion analysis of these genes found that only gly43F is critical for utilization of xylo‐oligosaccharides, xylan, and arabinoxylan. Heterologous expression of gly43F was sufficient for the utilization of xylo‐oligosaccharides in Escherichia coli. Additional analysis found that the xyn11A, xyn11B, abf43L, abf43K, and abf51A gene products were critical for utilization of arabinoxylan. Furthermore, a predicted transporter (CJA_1315) was required for effective utilization of xylan substrates, and we propose this unannotated gene be called xntA (xylan transporter A). Our major findings are (i) C. japonicus employs both secreted and surface associated enzymes for xylan degradation, which differs from the strategy used for cellulose degradation, and (ii) a single cytoplasmic β‐xylosidase is essential for the utilization of xylo‐oligosaccharides. [ABSTRACT FROM AUTHOR]

The high lignocellulolytic activity displayed by the soft-rot fungus Penicillium purpurogenum has made it a target for the study of novel lignocellulolytic enzymes. We have obtained a reference genome of 36.2 Mb of non-redundant sequence (11,057 protein-coding genes). The 49 largest scaffolds cover 90% of the assembly, and Core Eukaryotic Genes Mapping Approach (CEGMA) analysis reveals that our assembly captures almost all protein-coding genes. RNA-seq was performed and 93.1% of the reads aligned to the assembled genome. These data, plus the independent sequencing of a set of genes of lignocellulose-degrading enzymes, validate the quality of the genome sequence. P. purpurogenum shows a higher number of proteins with CAZy motifs, transcription factors and transporters as compared to other sequenced Penicillia. These results demonstrate the great potential for lignocellulolytic activity of this fungus and the possible use of its enzymes in related industrial applications. [ABSTRACT FROM AUTHOR]