Expression of a fungal glucuronoyl esterase in Populus: Effects on wood properties and saccharification efficiency

Gandla, Madhavi Latha; Derba‐Maceluch, Marta; Liu, Xiaokun; Gerber, Lorenz; Master, Emma R.; Mellerowicz, Ewa J.; Jönsson, Leif J.

doi:10.1016/j.phytochem.2014.06.002

Cited by 63 publications

(81 citation statements)

References 56 publications

(59 reference statements)

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“…Wood from internodes 44–60 was freeze-dried, ground to 0.5 mm particles (rough wood powder), and then ball milled to fine wood powder [37] or milled in a planetary ball mill PM400 (Retsch) for 9 h to obtain ball milled wood (BMW). The fine wood powder was analyzed by FT-IR spectroscopy and GC–MS pyrolysis as previously described [37].…”

Section: Methodsmentioning

confidence: 99%

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In muro deacetylation of xylan affects lignin properties and improves saccharification of aspen wood

Pawar

Derba‐Maceluch

Chong

et al. 2017

Biotechnol Biofuels

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BackgroundLignocellulose from fast growing hardwood species is a preferred source of polysaccharides for advanced biofuels and “green” chemicals. However, the extensive acetylation of hardwood xylan hinders lignocellulose saccharification by obstructing enzymatic xylan hydrolysis and causing inhibitory acetic acid concentrations during microbial sugar fermentation. To optimize lignocellulose for cost-effective saccharification and biofuel production, an acetyl xylan esterase AnAXE1 from Aspergillus niger was introduced into aspen and targeted to cell walls.Results AnAXE1-expressing plants exhibited reduced xylan acetylation and grew normally. Without pretreatment, their lignocellulose yielded over 25% more glucose per unit mass of wood (dry weight) than wild-type plants. Glucose yields were less improved (+7%) after acid pretreatment, which hydrolyses xylan. The results indicate that AnAXE1 expression also reduced the molecular weight of xylan, and xylan–lignin complexes and/or lignin co-extracted with xylan, increased cellulose crystallinity, altered the lignin composition, reducing its syringyl to guaiacyl ratio, and increased lignin solubility in dioxane and hot water. Lignin-associated carbohydrates became enriched in xylose residues, indicating a higher content of xylo-oligosaccharides.ConclusionsThis work revealed several changes in plant cell walls caused by deacetylation of xylan. We propose that deacetylated xylan is partially hydrolyzed in the cell walls, liberating xylo-oligosaccharides and their associated lignin oligomers from the cell wall network. Deacetylating xylan thus not only increases its susceptibility to hydrolytic enzymes during saccharification but also changes the cell wall architecture, increasing the extractability of lignin and xylan and facilitating saccharification.Electronic supplementary materialThe online version of this article (doi:10.1186/s13068-017-0782-4) contains supplementary material, which is available to authorized users.

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Section: Methodsmentioning

confidence: 99%

“…The fine wood powder was analyzed by FT-IR spectroscopy and GC–MS pyrolysis as previously described [37]. Data were analyzed using SIMCA-P (version 11.0.0.0, Umetrics AB, Sweden).…”

Section: Methodsmentioning

confidence: 99%

In muro deacetylation of xylan affects lignin properties and improves saccharification of aspen wood

Pawar

Derba‐Maceluch

Chong

et al. 2017

Biotechnol Biofuels

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“…Whereas, the expression of Phanerochaete carnosa glucuronyl esterase ( Pc GCE) in Arabidopsis [35] and aspen [36] induced morphological changes. Cell wall digestibility was mildly improved in An FAE-, An XA-, Xo AF and Pc GCE-expressing plants, but not in An AXE-expressing plants although the acetyl content was moderately decreased.…”

Section: Introductionmentioning

confidence: 99%

Active fungal GH115 α-glucuronidase produced in Arabidopsis thaliana affects only the UX1-reactive glucuronate decorations on native glucuronoxylans

et al. 2015

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BackgroundExpressing microbial polysaccharide-modifying enzymes in plants is an attractive approach to custom tailor plant lignocellulose and to study the importance of wall structures to plant development. Expression of α-glucuronidases in plants to modify the structures of glucuronoxylans has not been yet attempted. Glycoside hydrolase (GH) family 115 α-glucuronidases cleave the internal α-D-(4-O-methyl)glucopyranosyluronic acid ((Me)GlcA) from xylans or xylooligosaccharides. In this work, a GH115 α-glucuronidase from Schizophyllum commune, ScAGU115, was expressed in Arabidopsis thaliana and targeted to apoplast. The transgene effects on native xylans’ structures, plant development, and lignocellulose saccharification were evaluated and compared to those of knocked out glucuronyltransferases AtGUX1 and AtGUX2.ResultsThe ScAGU115 extracted from cell walls of Arabidopsis was active on the internally substituted aldopentaouronic acid (XUXX). The transgenic plants did not show any change in growth or in lignocellulose saccharification. The cell wall (Me)GlcA and other non-cellulosic sugars, as well as the lignin content, remained unchanged. In contrast, the gux1gux2 double mutant showed a 70% decrease in (Me)GlcA to xylose molar ratio, and, interestingly, a 60% increase in the xylose content. Whereas ScAGU115-expressing plants exhibited a decreased signal in native secondary walls from the monoclonal antibody UX1 that recognizes (Me)GlcA on non-acetylated xylan, the signal was not affected after wall deacetylation. In contrast, gux1gux2 mutant was lacking UX1 signals in both native and deacetylated cell walls. This indicates that acetyl substitution on the xylopyranosyl residue carrying (Me)GlcA or on the neighboring xylopyranosyl residues may restrict post-synthetic modification of xylans by ScAGU115 in planta.ConclusionsActive GH115 α-glucuronidase has been produced for the first time in plants. The cell wall–targeted ScAGU115 was shown to affect those glucuronate substitutions of xylan, which are accessible to UX1 antibody and constitute a small fraction in Arabidopsis, whereas majority of (Me)GlcA substitutions were resistant, most likely due to the shielding by acetyl groups. Plants expressing ScAGU115 did not show any defects under laboratory conditions indicating that the UX1 epitope of xylan is not essential under these conditions. Moreover the removal of the UX1 xylan epitope does not affect lignocellulose saccharification.Electronic supplementary materialThe online version of this article (doi:10.1186/s12896-015-0154-8) contains supplementary material, which is available to authorized users.

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“…With the Novozymes cellulase CellicCTec fortified with ␤-xylosidase, the presence of GE led to a 25% increase in the amount of pentoses released from a pretreated corn fiber (25). Additional indirect evidence for a possible role of GEs in plant cell wall degradation has so far been obtained by cloning fungal GE genes in plants (28,29). Expression of a fungal GE in Arabidopsis or aspen (Populus tremula) alters plant cell wall composition and architecture, improves extractability of xylan from plant biomass, and enhances enzymatic cellulose digestibility (28,29).…”

Section: Ges-esterases With Unexplored Biotechnological Potentialmentioning

confidence: 99%

“…Additional indirect evidence for a possible role of GEs in plant cell wall degradation has so far been obtained by cloning fungal GE genes in plants (28,29). Expression of a fungal GE in Arabidopsis or aspen (Populus tremula) alters plant cell wall composition and architecture, improves extractability of xylan from plant biomass, and enhances enzymatic cellulose digestibility (28,29). These effects were ascribed to reduced cell wall ester crosslinks leading to increased lignin deposition.…”

Section: Ges-esterases With Unexplored Biotechnological Potentialmentioning

confidence: 99%

Microbial Glucuronoyl Esterases: 10 Years after Discovery

Biely

2016

Appl Environ Microbiol

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A carbohydrate esterase called glucuronoyl esterase (GE) was discovered 10 years ago in a cellulolytic system of the wood-rotting fungus Schizophyllum commune. Genes coding for GEs were subsequently found in a number of microbial genomes, and a new family of carbohydrate esterases (CE15) has been established. The multidomain structures of GEs, together with their catalytic properties on artificial substrates and positive effect on enzymatic saccharification of plant biomass, led to the view that the esterases evolved for hydrolysis of the ester linkages between 4-O-methyl-D-glucuronic acid of plant glucuronoxylans and lignin alcohols, one of the crosslinks in the plant cell walls. This idea of the function of GEs is further supported by the effects of cloning of fungal GEs in plants and by very recently reported evidence for changes in the size of isolated lignin-carbohydrate complexes due to uronic acid de-esterification. These facts make GEs interesting candidates for biotechnological applications in plant biomass processing and genetic modification of plants. This article is a brief summary of current knowledge of these relatively recent and unexplored esterases.

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Expression of a fungal glucuronoyl esterase in Populus: Effects on wood properties and saccharification efficiency

Cited by 63 publications

References 56 publications

In muro deacetylation of xylan affects lignin properties and improves saccharification of aspen wood

In muro deacetylation of xylan affects lignin properties and improves saccharification of aspen wood

Active fungal GH115 α-glucuronidase produced in Arabidopsis thaliana affects only the UX1-reactive glucuronate decorations on native glucuronoxylans

Microbial Glucuronoyl Esterases: 10 Years after Discovery

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