Linking Plant Biology and Pretreatment: Understanding the Structure and Organization of the Plant Cell Wall and Interactions with Cellulosic Biofuel Production

Sustainable biofuel production from renewable biomass will require the efficient and complete use of all abundant sugars in the plant cell wall. Using the cellulolytic fungusNeurospora crassaas a model, we identified a xylodextrin transport and consumption pathway required for its growth on hemicellulose. Successful reconstitution of this xylodextrin utilization pathway inSaccharomyces cerevisiaerevealed that fungal xylose reductases act as xylodextrin reductases, and together with two hydrolases, generate intracellular xylose and xylitol. Xylodextrin consumption using xylodextrin reductases and tandem intracellular hydrolases greatly expands the capacity of yeasts to use plant cell wall-derived sugars, and should be adaptable to increase the efficiency of both first-generation and next-generation biofuel production.

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Expanding xylose metabolism in yeast for plant cell wall conversion to biofuels

eLife ◽

10.7554/elife.05896 ◽

2015 ◽

Vol 4 ◽

Cited By ~ 23

Author(s):

Xin Li ◽

Vivian Yaci Yu ◽

Yuping Lin ◽

Kulika Chomvong ◽

Raíssa Estrela ◽

...

Keyword(s):

Cell Wall ◽

Plant Cell ◽

First Generation ◽

Plant Cell Wall ◽

Biofuel Production ◽

Xylose Metabolism ◽

Metabolic Intermediates ◽

Renewable Biomass ◽

Generation Biofuel ◽

Utilization Pathway

Sustainable biofuel production from renewable biomass will require the efficient and complete use of all abundant sugars in the plant cell wall. Using the cellulolytic fungus Neurospora crassa as a model, we identified a xylodextrin transport and consumption pathway required for its growth on hemicellulose. Reconstitution of this xylodextrin utilization pathway in Saccharomyces cerevisiae revealed that fungal xylose reductases act as xylodextrin reductases, producing xylosyl-xylitol oligomers as metabolic intermediates. These xylosyl-xylitol intermediates are generated by diverse fungi and bacteria, indicating that xylodextrin reduction is widespread in nature. Xylodextrins and xylosyl-xylitol oligomers are then hydrolyzed by two hydrolases to generate intracellular xylose and xylitol. Xylodextrin consumption using a xylodextrin transporter, xylodextrin reductases and tandem intracellular hydrolases in cofermentations with sucrose and glucose greatly expands the capacity of yeast to use plant cell wall-derived sugars and has the potential to increase the efficiency of both first-generation and next-generation biofuel production.

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Biochemical Analyses of Multiple Endoxylanases from the Rumen Bacterium Ruminococcus albus 8 and Their Synergistic Activities with Accessory Hemicellulose-Degrading Enzymes

Applied and Environmental Microbiology ◽

10.1128/aem.00353-11 ◽

2011 ◽

Vol 77 (15) ◽

pp. 5157-5169 ◽

Cited By ~ 33

Author(s):

Young Hwan Moon ◽

Michael Iakiviak ◽

Stefan Bauer ◽

Roderick I. Mackie ◽

Isaac K. O. Cann

Keyword(s):

Cell Wall ◽

Plant Cell ◽

Plant Cell Wall ◽

Biofuel Production ◽

Rumen Bacterium ◽

Ruminococcus Albus ◽

Content Type ◽

Chemical Complexity ◽

Degrading Enzymes ◽

Modular Architectures

ABSTRACTRuminococcus albus8 is a ruminal bacterium capable of metabolizing hemicellulose and cellulose, the major components of the plant cell wall. The enzymes that allow this bacterium to capture energy from the two polysaccharides, therefore, have potential application in plant cell wall depolymerization, a process critical to biofuel production. For this purpose, a partial genome sequence ofR. albus8 was generated. The genomic data depicted a bacterium endowed with multiple forms of plant cell wall-degrading enzymes. The endoxylanases ofR. albus8 exhibited diverse modular architectures, including incorporation of a catalytic module, a carbohydrate binding module, and a carbohydrate esterase module in a single polypeptide. The accessory enzymes of xylan degradation were a β-xylosidase, an α-l-arabinofuranosidase, and an α-glucuronidase. We hypothesized that due to the chemical complexity of the hemicellulose encountered in the rumen, the bacterium uses multiple endoxylanases, with subtle differences in substrate specificities, to attack the substrate, while the accessory enzymes hydrolyze the products to simple sugars for metabolism. To test this hypothesis, the genes encoding the predicted endoxylanases were expressed, and the proteins were biochemically characterized either alone or in combination with accessory enzymes. The different endoxylanase families exhibited different patterns of product release, with the family 11 endoxylanases releasing more products in synergy with the accessory enzymes from the more complex substrates. Aside from the insights into hemicellulose degradation byR. albus8, this report should enhance our knowledge on designing effective enzyme cocktails for release of fermentable sugars in the biofuel industry.

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Plant Cell Wall Proteomics: A Focus on Monocot Species, Brachypodium distachyon, Saccharum spp. and Oryza sativa

International Journal of Molecular Sciences ◽

10.3390/ijms20081975 ◽

2019 ◽

Vol 20 (8) ◽

pp. 1975 ◽

Cited By ~ 6

Author(s):

Maria Juliana Calderan-Rodrigues ◽

Juliana Guimarães Fonseca ◽

Fabrício Edgar de Moraes ◽

Laís Vaz Setem ◽

Amanda Carmanhanis Begossi ◽

...

Keyword(s):

Cell Wall ◽

Oryza Sativa ◽

Plant Cell ◽

Cell Walls ◽

Plant Cell Wall ◽

Developmental Stages ◽

Brachypodium Distachyon ◽

Cell Types ◽

Biofuel Production ◽

Saccharum Spp

Plant cell walls mostly comprise polysaccharides and proteins. The composition of monocots’ primary cell walls differs from that of dicots walls with respect to the type of hemicelluloses, the reduction of pectin abundance and the presence of aromatic molecules. Cell wall proteins (CWPs) differ among plant species, and their distribution within functional classes varies according to cell types, organs, developmental stages and/or environmental conditions. In this review, we go deeper into the findings of cell wall proteomics in monocot species and make a comparative analysis of the CWPs identified, considering their predicted functions, the organs analyzed, the plant developmental stage and their possible use as targets for biofuel production. Arabidopsis thaliana CWPs were considered as a reference to allow comparisons among different monocots, i.e., Brachypodium distachyon, Saccharum spp. and Oryza sativa. Altogether, 1159 CWPs have been acknowledged, and specificities and similarities are discussed. In particular, a search for A. thaliana homologs of CWPs identified so far in monocots allows the definition of monocot CWPs characteristics. Finally, the analysis of monocot CWPs appears to be a powerful tool for identifying candidate proteins of interest for tailoring cell walls to increase biomass yield of transformation for second-generation biofuels production.

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Feruloyl Esterase Fae1 is Required Specifically for Host Colonisation by The Rice-Blast Fungus Magnaporthe Oryzae

10.21203/rs.3.rs-591209/v1 ◽

2021 ◽

Author(s):

Akhil Thaker ◽

Khyati Mehta ◽

Rajesh Patkar

Keyword(s):

Cell Wall ◽

Ferulic Acid ◽

Plant Cell ◽

Magnaporthe Oryzae ◽

Plant Cell Wall ◽

Biofuel Production ◽

Feruloyl Esterase ◽

Potential Candidate ◽

Blast Fungus ◽

Host Invasion

Abstract Plant cell wall acts as a primary barrier for microbial pathogens during infection. A cell wall degrading enzyme thus may be a crucial virulence factor, as it may aid the pathogen in successful host invasion. Nine genes coding for feruloyl esterases (Fae), likely involved in plant cell wall degradation, have been annotated in the genome of the cereal-blast fungus Magnaporthe oryzae . However, role of any Fae in pathogenicity of M. oryzae remains hitherto under explored. Here, we identified FAE1 gene (MGG_08737) that was significantly upregulated during host penetration and subsequent colonisation stages of infection. Accordingly, while deletion of FAE1 in M. oryzae did not affect the vegetative growth and asexual development, the fae1Δ mutant showed significantly reduced pathogenesis on rice plants, mainly due to impaired host invasion and colonisation. Very few (<10%) fae1Δ appressoria that formed the primary invasive hyphae, failed to elaborate from the first invaded cell to the neighboring plant cells. Interestingly, exogenously added glucose, as a simple carbon source, or ferulic acid, a product of the Fae activity, significantly supported the invasive growth of the fae1Δ mutant. We show that the Fae1-based feruloyl esterase activity, by targeting the plant cell wall, plays an important role in accumulating ferulic acid and/or sugar molecules, as a likely energy source, to enable host invasion and colonisation by M. oryzae. Given its role in plant cell wall digestion and host colonisation, M. oryzae Fae1 could be a potential candidate for a novel antifungal strategy and a biotechnological application in biofuel production.

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