scholarly journals Thermophilic Degradation of Hemicellulose, a Critical Feedstock in the Production of Bioenergy and Other Value-Added Products

2020 ◽  
Vol 86 (7) ◽  
Author(s):  
Isaac Cann ◽  
Gabriel V. Pereira ◽  
Ahmed M. Abdel-Hamid ◽  
Heejin Kim ◽  
Daniel Wefers ◽  
...  
Keyword(s):  
Cell Wall ◽  
Plant Cell ◽  
Plant Cell Wall ◽  
Plant Biomass ◽  
Animal Feed ◽  
Value Added ◽  
Building Blocks ◽  
Economic Feasibility ◽  
Renewable Fuels ◽  
Microbial Enzymes

ABSTRACT Renewable fuels have gained importance as the world moves toward diversifying its energy portfolio. A critical step in the biomass-to-bioenergy initiative is deconstruction of plant cell wall polysaccharides to their unit sugars for subsequent fermentation to fuels. To acquire carbon and energy for their metabolic processes, diverse microorganisms have evolved genes encoding enzymes that depolymerize polysaccharides to their carbon/energy-rich building blocks. The microbial enzymes mostly target the energy present in cellulose, hemicellulose, and pectin, three major forms of energy storage in plants. In the effort to develop bioenergy as an alternative to fossil fuel, a common strategy is to harness microbial enzymes to hydrolyze cellulose to glucose for fermentation to fuels. However, the conversion of plant biomass to renewable fuels will require both cellulose and hemicellulose, the two largest components of the plant cell wall, as feedstock to improve economic feasibility. Here, we explore the enzymes and strategies evolved by two well-studied bacteria to depolymerize the hemicelluloses xylan/arabinoxylan and mannan. The sets of enzymes, in addition to their applications in biofuels and value-added chemical production, have utility in animal feed enzymes, a rapidly developing industry with potential to minimize adverse impacts of animal agriculture on the environment.

scholarly journals The regulatory and transcriptional landscape associated with carbon utilization in a filamentous fungus

2020 ◽  
Vol 117 (11) ◽  
pp. 6003-6013 ◽  
Author(s):  
Vincent W. Wu ◽  
Nils Thieme ◽  
Lori B. Huberman ◽  
Axel Dietschmann ◽  
David J. Kowbel ◽  
...  
Keyword(s):  
Cell Wall ◽  
Transcription Factors ◽  
Plant Cell ◽  
Plant Cell Wall ◽  
Plant Biomass ◽  
Carbon Sources ◽  
Cell Wall Degrading Enzymes ◽  
Degrading Enzymes ◽  
Genes Encoding

Filamentous fungi, such asNeurospora crassa, are very efficient in deconstructing plant biomass by the secretion of an arsenal of plant cell wall-degrading enzymes, by remodeling metabolism to accommodate production of secreted enzymes, and by enabling transport and intracellular utilization of plant biomass components. Although a number of enzymes and transcriptional regulators involved in plant biomass utilization have been identified, how filamentous fungi sense and integrate nutritional information encoded in the plant cell wall into a regulatory hierarchy for optimal utilization of complex carbon sources is not understood. Here, we performed transcriptional profiling ofN. crassaon 40 different carbon sources, including plant biomass, to provide data on how fungi sense simple to complex carbohydrates. From these data, we identified regulatory factors inN. crassaand characterized one (PDR-2) associated with pectin utilization and one with pectin/hemicellulose utilization (ARA-1). Using in vitro DNA affinity purification sequencing (DAP-seq), we identified direct targets of transcription factors involved in regulating genes encoding plant cell wall-degrading enzymes. In particular, our data clarified the role of the transcription factor VIB-1 in the regulation of genes encoding plant cell wall-degrading enzymes and nutrient scavenging and revealed a major role of the carbon catabolite repressor CRE-1 in regulating the expression of major facilitator transporter genes. These data contribute to a more complete understanding of cross talk between transcription factors and their target genes, which are involved in regulating nutrient sensing and plant biomass utilization on a global level.

scholarly journals Comparative Analysis of Herbaceous and Woody Cell Wall Digestibility by Pathogenic Fungi

Molecules ◽  
2021 ◽  
Vol 26 (23) ◽  
pp. 7220
Author(s):  
Yanhua Dou ◽  
Yan Yang ◽  
Nitesh Kumar Mund ◽  
Yanping Wei ◽  
Yisong Liu ◽  
...  
Keyword(s):  
Cell Wall ◽  
Plant Cell ◽  
Fungal Pathogens ◽  
Plant Cell Wall ◽  
Apple Tree ◽  
Plant Biomass ◽  
Genomic Analysis ◽  
Pathogenic Fungi ◽  
Cell Wall Degrading Enzymes ◽  
Enzyme Activity Assay

Fungal pathogens have evolved combinations of plant cell-wall-degrading enzymes (PCWDEs) to deconstruct host plant cell walls (PCWs). An understanding of this process is hoped to create a basis for improving plant biomass conversion efficiency into sustainable biofuels and bioproducts. Here, an approach integrating enzyme activity assay, biomass pretreatment, field emission scanning electron microscopy (FESEM), and genomic analysis of PCWDEs were applied to examine digestibility or degradability of selected woody and herbaceous biomass by pathogenic fungi. Preferred hydrolysis of apple tree branch, rapeseed straw, or wheat straw were observed by the apple-tree-specific pathogen Valsa mali, the rapeseed pathogen Sclerotinia sclerotiorum, and the wheat pathogen Rhizoctonia cerealis, respectively. Delignification by peracetic acid (PAA) pretreatment increased PCW digestibility, and the increase was generally more profound with non-host than host PCW substrates. Hemicellulase pretreatment slightly reduced or had no effect on hemicellulose content in the PCW substrates tested; however, the pretreatment significantly changed hydrolytic preferences of the selected pathogens, indicating a role of hemicellulose branching in PCW digestibility. Cellulose organization appears to also impact digestibility of host PCWs, as reflected by differences in cellulose microfibril organization in woody and herbaceous PCWs and variation in cellulose-binding domain organization in cellulases of pathogenic fungi, which is known to influence enzyme access to cellulose. Taken together, this study highlighted the importance of chemical structure of both hemicelluloses and cellulose in host PCW digestibility by fungal pathogens.

scholarly journals Induction of Genes Encoding Plant Cell Wall-Degrading Carbohydrate-Active Enzymes by Lignocellulose-Derived Monosaccharides and Cellobiose in the White-Rot FungusDichomitus squalens

2018 ◽  
Vol 84 (11) ◽  
Author(s):  
Sara Casado López ◽  
Mao Peng ◽  
Tedros Yonatan Issak ◽  
Paul Daly ◽  
Ronald P. de Vries ◽  
...  
Keyword(s):  
Cell Wall ◽  
Plant Cell ◽  
Plant Cell Wall ◽  
Plant Biomass ◽  
Expression Patterns ◽  
Fine Tuning ◽  
White Rot ◽  
White Rot Fungus ◽  
Content Type ◽  
Dichomitus Squalens

ABSTRACTFungi can decompose plant biomass into small oligo- and monosaccharides to be used as carbon sources. Some of these small molecules may induce metabolic pathways and the production of extracellular enzymes targeted for degradation of plant cell wall polymers. Despite extensive studies in ascomycete fungi, little is known about the nature of inducers for the lignocellulolytic systems of basidiomycetes. In this study, we analyzed six sugars known to induce the expression of lignocellulolytic genes in ascomycetes for their role as inducers in the basidiomycete white-rot fungusDichomitus squalensusing a transcriptomic approach. This identified cellobiose andl-rhamnose as the main inducers of cellulolytic and pectinolytic genes, respectively, ofD. squalens. Our results also identified differences in gene expression patterns between dikaryotic and monokaryotic strains ofD. squalenscultivated on plant biomass-derived monosaccharides and the disaccharide cellobiose. This suggests that despite conservation of the induction between these two genetic forms ofD. squalens, the fine-tuning in the gene regulation of lignocellulose conversion is differently organized in these strains.IMPORTANCEWood-decomposing basidiomycete fungi have a major role in the global carbon cycle and are promising candidates for lignocellulosic biorefinery applications. However, information on which components trigger enzyme production is currently lacking, which is crucial for the efficient use of these fungi in biotechnology. In this study, transcriptomes of the white-rot fungusDichomitus squalensfrom plant biomass-derived monosaccharide and cellobiose cultures were studied to identify compounds that induce the expression of genes involved in plant biomass degradation.

scholarly journals Direct Cryo Writing of Aerogels Via 3D Printing of Aligned Cellulose Nanocrystals Inspired by the Plant Cell Wall

2019 ◽  
Vol 3 (2) ◽  
pp. 46 ◽  
Author(s):  
Doron Kam ◽  
Michael Chasnitsky ◽  
Chen Nowogrodski ◽  
Ido Braslavsky ◽  
Tiffany Abitbol ◽  
...  
Keyword(s):  
Cell Wall ◽  
3D Printing ◽  
Plant Cell ◽  
Cellulose Nanocrystals ◽  
Plant Cell Wall ◽  
Building Blocks ◽  
Freeze Casting ◽  
Aqueous Mixture ◽  
Manufacturing Technologies ◽  
Directional Freezing

Aerogel objects inspired by plant cell wall components and structures were fabricated using extrusion-based 3D printing at cryogenic temperatures. The printing process combines 3D printing with the alignment of rod-shaped nanoparticles through the freeze-casting of aqueous inks. We have named this method direct cryo writing (DCW) as it encompasses in a single processing step traditional directional freeze casting and the spatial fidelity of 3D printing. DCW is demonstrated with inks that are composed of an aqueous mixture of cellulose nanocrystals (CNCs) and xyloglucan (XG), which are the major building blocks of plant cell walls. Rapid fixation of the inks is achieved through tailored rheological properties and controlled directional freezing. Morphological evaluation revealed the role of ice crystal growth in the alignment of CNCs and XG. The structure of the aerogels changed from organized and tubular to disordered and flakey pores with an increase in XG content. The internal structure of the printed objects mimics the structure of various wood species and can therefore be used to create wood-like structures via additive manufacturing technologies using only renewable wood-based materials.

scholarly journals Cryogenian Origin and Subsequent Diversification of the Plant Cell-Wall Enzyme XTH Family

2021 ◽  
Author(s):  
Naoki Shinohara ◽  
Kazuhiko Nishitani
Keyword(s):  
Cell Wall ◽  
Plant Cell ◽  
Evolutionary History ◽  
Plant Cell Wall ◽  
Plant Biomass ◽  
Land Plant ◽  
Cell Wall Polysaccharides ◽  
Fungal Cell ◽  
Considerable Uncertainty ◽  
History Of

Abstract All land plants encode large multigene families of xyloglucan endotransglucosylase/hydrolases (XTHs), plant-specific enzymes that cleave and reconnect plant cell-wall polysaccharides. Despite the ubiquity of these enzymes, considerable uncertainty remains regarding the evolutionary history of the XTH family. Phylogenomic and comparative analyses in this study traced the non-plant origins of the XTH family to Alphaproteobacteria ExoKs, bacterial enzymes involved in loosening biofilms, rather than Firmicutes licheninases, plant biomass digesting enzymes, as previously supposed. The relevant horizontal gene transfer (HGT) event was mapped to the divergence of non-swimming charophycean algae in the Cryogenian geological period. This HGT event was the likely origin of charophycean EG16-2s, which are putative intermediates between ExoKs and XTHs. Another HGT event in the Cryogenian may have led from EG16-2s or ExoKs to fungal CRHs, enzymes that cleave and reconnect chitin and glucans in fungal cell walls. This successive transfer of enzyme-encoding genes may have supported the adaptation of plants and fungi to the ancient icy environment by facilitating their sessile lifestyles. Furthermore, several protein evolutionary steps, including coevolution of substrate-interacting residues and putative intra-family gene fusion, occurred in the land plant lineage and drove diversification of the XTH family. At least some of those events correlated with the evolutionary gain of broader substrate specificities, which may have underpinned the expansion of the XTH family by enhancing duplicated gene survival. Together, this study highlights the Precambrian evolution of life and the mode of multigene family expansion in the evolutionary history of the XTH family.

scholarly journals Activating Intrinsic Carbohydrate-Active Enzymes of the Smut Fungus Ustilago maydis for the Degradation of Plant Cell Wall Components

2016 ◽  
Vol 82 (17) ◽  
pp. 5174-5185 ◽  
Author(s):  
Elena Geiser ◽  
Michèle Reindl ◽  
Lars M. Blank ◽  
Michael Feldbrügge ◽  
Nick Wierckx ◽  
...  
Keyword(s):  
Cell Wall ◽  
Plant Cell ◽  
Plant Cell Wall ◽  
Hydrolytic Enzymes ◽  
Value Added ◽  
Ustilago Maydis ◽  
Smut Fungus ◽  
Content Type ◽  
Cell Wall Components ◽  
Wall Components

ABSTRACTThe microbial conversion of plant biomass to valuable products in a consolidated bioprocess could greatly increase the ecologic and economic impact of a biorefinery. Current strategies for hydrolyzing plant material mostly rely on the external application of carbohydrate-active enzymes (CAZymes). Alternatively, production organisms can be engineered to secrete CAZymes to reduce the reliance on externally added enzymes. Plant-pathogenic fungi have a vast repertoire of hydrolytic enzymes to sustain their lifestyle, but expression of the corresponding genes is usually highly regulated and restricted to the pathogenic phase. Here, we present a new strategy in using the biotrophic smut fungusUstilago maydisfor the degradation of plant cell wall components by activating its intrinsic enzyme potential during axenic growth. This fungal model organism is fully equipped with hydrolytic enzymes, and moreover, it naturally produces value-added substances, such as organic acids and biosurfactants. To achieve the deregulated expression of hydrolytic enzymes during the industrially relevant yeast-like growth in axenic culture, the native promoters of the respective genes were replaced by constitutively active synthetic promoters. This led to an enhanced conversion of xylan, cellobiose, and carboxymethyl cellulose to fermentable sugars. Moreover, a combination of strains with activated endoglucanase and β-glucanase increased the release of glucose from carboxymethyl cellulose and regenerated amorphous cellulose, suggesting that mixed cultivations could be a means for degrading more complex substrates in the future. In summary, this proof of principle demonstrates the potential applicability of activating the expression of native CAZymes from phytopathogens in a biocatalytic process.IMPORTANCEThis study describes basic experiments that aim at the degradation of plant cell wall components by the smut fungusUstilago maydis. As a plant pathogen, this fungus contains a set of lignocellulose-degrading enzymes that may be suited for biomass degradation. However, its hydrolytic enzymes are specifically expressed only during plant infection. Here, we provide the proof of principle that these intrinsic enzymes can be synthetically activated during the industrially relevant yeast-like growth. The fungus is known to naturally synthesize valuable compounds, such as itaconate or glycolipids. Therefore, it could be suited for use in a consolidated bioprocess in which more complex and natural substrates are simultaneously converted to fermentable sugars and to value-added compounds in the future.

scholarly journals Systems identification and characterization of β-glucuronosyltransferase genes involved in arabinogalactan-protein biosynthesis in plant genomes

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Oyeyemi Olugbenga Ajayi ◽  
Allan M. Showalter
Keyword(s):  
Gene Expression ◽  
Cell Wall ◽  
Plant Cell ◽  
Molecular Mechanisms ◽  
Plant Cell Wall ◽  
Plant Biomass ◽  
Functional Divergence ◽  
Arabinogalactan Protein ◽  
Plant Genomes ◽  
Cell Wall Polymers

AbstractUtilizing plant biomass for bioethanol production requires an understanding of the molecular mechanisms involved in plant cell wall assembly. Arabinogalactan-proteins (AGPs) are glycoproteins that interact with other cell wall polymers to influence plant growth and developmental processes. Glucuronic acid, which is transferred to the AGP glycan by β-glucuronosyltransferases (GLCATs), is the only acidic sugar in AGPs with the ability to bind calcium. We carried out a comprehensive genome-wide analysis of a putative GLCAT gene family involved in AGP biosynthesis by examining its sequence diversity, genetic architecture, phylogenetic and motif characteristics, selection pressure and gene expression in plants. We report the identification of 161 putative GLCAT genes distributed across 14 plant genomes and a widely conserved GLCAT catalytic domain. We discovered a phylogenetic clade shared between bryophytes and higher land plants of monocot grass and dicot lineages and identified positively selected sites that do not result in functional divergence of GLCATs. RNA-seq and microarray data analyses of the putative GLCAT genes revealed gene expression signatures that likely influence the assembly of plant cell wall polymers which is critical to the overall growth and development of edible and bioenergy crops.

scholarly journals Characterisation of the Effect of the Spatial Organisation of Hemicellulases on the Hydrolysis of Plant Biomass Polymer

2020 ◽  
Vol 21 (12) ◽  
pp. 4360
Author(s):  
Thomas Enjalbert ◽  
Marion De La Mare ◽  
Pierre Roblin ◽  
Louise Badruna ◽  
Thierry Vernet ◽  
...  
Keyword(s):  
Cell Wall ◽  
Plant Cell ◽  
Plant Cell Wall ◽  
Plant Biomass ◽  
Reducing Sugar ◽  
Intrinsic Activity ◽  
X Rays ◽  
Spatial Organisation ◽  
The Impact ◽  
Hydrolysis Of

Synergism between enzymes is of crucial importance in cell metabolism. This synergism occurs often through a spatial organisation favouring proximity and substrate channelling. In this context, we developed a strategy for evaluating the impact of the geometry between two enzymes involved in nature in the recycling of the carbon derived from plant cell wall polymers. By using an innovative covalent association process using two protein fragments, Jo and In, we produced two bi-modular chimeric complexes connecting a xylanase and a xylosidase, involved in the deconstruction of xylose-based plant cell wall polymer. We first show that the intrinsic activity of the individual enzymes was preserved. Small Angle X-rays Scattering (SAXS) analysis of the complexes highlighted two different spatial organisations in solution, affecting both the distance between the enzymes (53 Å and 28 Å) and the distance between the catalytic pockets (94 Å and 75 Å). Reducing sugar and HPAEC-PAD analysis revealed different behaviour regarding the hydrolysis of Beechwood xylan. After 24 h of hydrolysis, one complex was able to release a higher amount of reducing sugar compare to the free enzymes (i.e., 15,640 and 14,549 µM of equivalent xylose, respectively). However, more interestingly, the two complexes were able to release variable percentages of xylooligosaccharides compared to the free enzymes. The structure of the complexes revealed some putative steric hindrance, which impacted both enzymatic efficiency and the product profile. This report shows that controlling the spatial geometry between two enzymes would help to better investigate synergism effect within complex multi-enzymatic machinery and control the final product.

scholarly journals Heterologous Expression of Plant Cell Wall Degrading Enzymes for Effective Production of Cellulosic Biofuels

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Sang-Kyu Jung ◽  
Vinuselvi Parisutham ◽  
Seong Hun Jeong ◽  
Sung Kuk Lee
Keyword(s):  
Cell Wall ◽  
Heterologous Expression ◽  
Plant Cell ◽  
Plant Cell Wall ◽  
Plant Biomass ◽  
Consolidated Bioprocessing ◽  
Host Organism ◽  
Cell Wall Degrading Enzymes ◽  
Degrading Enzymes ◽  
The Cost

A major technical challenge in the cost-effective production of cellulosic biofuel is the need to lower the cost of plant cell wall degrading enzymes (PCDE), which is required for the production of sugars from biomass. Several competitive, low-cost technologies have been developed to produce PCDE in different host organisms such asEscherichia coli, Zymomonas mobilis, and plant. Selection of an ideal host organism is very important, because each host organism has its own unique features. Synthetic biology-aided tools enable heterologous expression of PCDE in recombinantE. coliorZ. mobilisand allow successful consolidated bioprocessing (CBP) in these microorganisms.In-plantaexpression provides an opportunity to simplify the process of enzyme production and plant biomass processing and leads to self-deconstruction of plant cell walls. Although the future of currently available technologies is difficult to predict, a complete and viable platform will most likely be available through the integration of the existing approaches with the development of breakthrough technologies.

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