Biodegradation of lignin-carbohydrate complexes

Abstract

Covalent lignin-carbohydrate (LC) linkages exist in lignocellulose from wood and groups herbaceous plants.In wood, they consist of ester and ether linkages through sugar hydroxyl to the a-carbanol of phenylpropane subunits in lignin. In grasses, ferulic and p-coumaric acids are esterified to hemicelluloses and lignin, respectively. Hemicelluloses also contain substituents and side groups that restrict enzymatic attack. Watersoluble lignin-carbohydrate complexes (LCCs) often precipitate during digestion with polysaccharidases, and the residual sugars are more diverse than the bulk hemicellulose. A number of microbial esterases and hemicellulose polysaccharidases including acetyl xylan esterase, ferulic acid esterase, and p-coumaric esterase attack hemicellulose side chains. Accessory hemicellulases include a-L-arabinofuranosidase and a-methyl-glucuranosidase. Both of these side chains are involved in LC bonds. [~-Glucosidase will attach sugar residues to lignin degradation products and when carbohydrate is attached to lignin, lignin peroxidase will depolymerize the lignin more readily.A b breviations: APPL -acid precipitable polymeric lignin; CB Qase -cellobioquinone oxidoreduct ase; LClignincarbohydrate; LCC(s) -lignin-carbohydrate complex; DHP -Dehydrogenative polymerisate; DMSO -dimethylsulfoxide; DP -degree of polymerisation; MWEL -milled wood enzyme lignin; MWL -milled wood lignin (not digested with carbohydrases)

Lignocellulose biodegradation: Fundamentals and applications

“…The accessibility of cell wall polysaccharides from the plant to microbial enzymes is dictated by the degree to which they are associated with phenolic polymers (Chesson 1981;Kuhad et al 1997). In grasses, ferulic and pcoumaric acids are esterified to hemicellulose and lignin (Jeffries 1990;Mueller-Harvey & Hartley 1986). Xylans appear to be a major interface between lignin and other carbohydrate components (Cornu et al 1994;Jeffries 1990).…”

“…In grasses, ferulic and pcoumaric acids are esterified to hemicellulose and lignin (Jeffries 1990;Mueller-Harvey & Hartley 1986). Xylans appear to be a major interface between lignin and other carbohydrate components (Cornu et al 1994;Jeffries 1990). Ferulic acid anchors hydrophobic lignins to hydrophilic polysaccharides via alkali-sensitive ester bonds.…”

New alternative energy pathway for chemical pulp mills: From traditional fibers to methane production

“…where Mamount is the methane amount of kg produced per one air-dried ton of substrate (Jeffries, 1990). …”

“…(3) and (4) in order to estimate the energetic output from a traditional fiber to an energy 21 production scheme (Table 4). Energy estimations suggest that using BLFiber as feedstock 22 for AD produces the highest amount of energy of 13.5 gigajoules per air dry ton (GJ/adt). An estimated sludge production is important to compute and factor into the calculations.…”

Sacarificação enzimática de bagaços de cana-de-açúcar pré-tratados com sulfito ácido

“…As hemiceluloses de gramíneas, por exemplo, são geralmente caracterizadas pela presença de arabinoglucuronoxilanas (Figura 4). As paredes celulares de gramíneas também contêm grandes quantidades de ácidos hidroxicinâmicos, ferúlico e cumárico (BEUKES et al, 2008;JEFFRIES, 1990;LAVARACK;GRIFFIN;RODMAN, 2002;SASKA;OZER, 1995). No bagaço de cana-de-açúcar, as hemiceluloses aparecem na proporção de 25 % a 27 % e, quando são hidrolisadas por ácido, podem gerar xilose, arabinose, ácido urônico, ácido acético e furfural.…”