Chemical Composition and Enzymatic Degradability of Xylem and Nonxylem Walls Isolated from Alfalfa Internodes

Grabber, John H.; Panciera, M. T.; Hatfield, Ronald D.

doi:10.1021/jf011598c

Cited by 26 publications

(18 citation statements)

References 44 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The inverse correlation seen for the lignin content or the absorbance assigned to aromatics with the levels of cellulose conversion is in close agreement with data reported in previous studies by Grabber et al . [29] for mature and immature alfalfa fibers, Jung and Casler [27] for maize stems at various stages of maturation, Chen and Dixon [30] for transgenic alfalfa, and Lee et al . [31] for selectively delignified wood.…”

Section: Resultsmentioning

confidence: 99%

Topochemical distribution of lignin and hydroxycinnamic acids in sugar-cane cell walls and its correlation with the enzymatic hydrolysis of polysaccharides

Siqueira

Milagres

Carvalho

et al. 2011

Biotechnol Biofuels

View full text Add to dashboard Cite

BackgroundLignin and hemicelluloses are the major components limiting enzyme infiltration into cell walls. Determination of the topochemical distribution of lignin and aromatics in sugar cane might provide important data on the recalcitrance of specific cells. We used cellular ultraviolet (UV) microspectrophotometry (UMSP) to topochemically detect lignin and hydroxycinnamic acids in individual fiber, vessel and parenchyma cell walls of untreated and chlorite-treated sugar cane. Internodes, presenting typical vascular bundles and sucrose-storing parenchyma cells, were divided into rind and pith fractions.ResultsVascular bundles were more abundant in the rind, whereas parenchyma cells predominated in the pith region. UV measurements of untreated fiber cell walls gave absorbance spectra typical of grass lignin, with a band at 278 nm and a pronounced shoulder at 315 nm, assigned to the presence of hydroxycinnamic acids linked to lignin and/or to arabino-methylglucurono-xylans. The cell walls of vessels had the highest level of lignification, followed by those of fibers and parenchyma. Pith parenchyma cell walls were characterized by very low absorbance values at 278 nm; however, a distinct peak at 315 nm indicated that pith parenchyma cells are not extensively lignified, but contain significant amounts of hydroxycinnamic acids. Cellular UV image profiles scanned with an absorbance intensity maximum of 278 nm identified the pattern of lignin distribution in the individual cell walls, with the highest concentration occurring in the middle lamella and cell corners. Chlorite treatment caused a rapid removal of hydroxycinnamic acids from parenchyma cell walls, whereas the thicker fiber cell walls were delignified only after a long treatment duration (4 hours). Untreated pith samples were promptly hydrolyzed by cellulases, reaching 63% of cellulose conversion after 72 hours of hydrolysis, whereas untreated rind samples achieved only 20% hydrolyzation.ConclusionThe low recalcitrance of pith cells correlated with the low UV-absorbance values seen in parenchyma cells. Chlorite treatment of pith cells did not enhance cellulose conversion. By contrast, application of the same treatment to rind cells led to significant removal of hydroxycinnamic acids and lignin, resulting in marked enhancement of cellulose conversion by cellulases.

show abstract

Section: Resultsmentioning

confidence: 99%

Topochemical distribution of lignin and hydroxycinnamic acids in sugar-cane cell walls and its correlation with the enzymatic hydrolysis of polysaccharides

Siqueira

Milagres

Carvalho

et al. 2011

Biotechnol Biofuels

View full text Add to dashboard Cite

show abstract

“…Internodal cell walls are comprised to a large extent of highly lignified xylem vessels as compared to the non-xylem vessels. In previous work on alfalfa (Grabber et al, 2002), it was found that the xylem portion of the internodes was rather difficult to hydrolyze compared to the non-xylem portion. This may be due to restricted degradation of xyloglucan in the primary and secondary cell walls, due to greater interaction with lignin.…”

Section: Compositional Effectmentioning

confidence: 99%

Effect of particle size based separation of milled corn stover on AFEX pretreatment and enzymatic digestibility

Chundawat

Balan

Dale

2006

Biotech & Bioengineering

333

139

View full text Add to dashboard Cite

Particle size and compositional variance are found to have a substantial influence on ammonia fiber explosion (AFEX) pretreatment and enzymatic hydrolysis of lignocellulosic biomass. Corn stover was milled and fractionated into particle sizes of varying composition. The larger particle size fractions (rich in corn cob and stalk portions) were found to be more recalcitrant to hydrolysis compared to the smaller size fractions (rich in leaves and husk portion). Electron spectroscopy for chemical analysis (ESCA) and Fourier transform infrared spectroscopy (FTIR) were used for biomass surface and bulk compositional analysis, respectively. The ESCA results showed a 15-30% decrease in the O/C (oxygen to carbon) ratio after the pretreatment indicating an increase in the hydrophobic nature of biomass surface. FTIR results confirmed cleavage of the lignin-carbohydrate complex (LCC) for the AFEX-treated fractions. The spectroscopic results indicate the extraction of cleaved lignin phenolic fragments and other cell wall extractives to the biomass surface upon AFEX. Water washing of AFEX-treated fractions removed some of the hydrophobic extractives resulting in a 13% weight loss (dry weight basis). Phenolic content of wash stream was evaluated by the modified Prussian blue (MPB) method. Removal of ligno-phenolic extractives from the AFEX-treated biomass by water washing vastly improved the glucan conversion as compared to the unwashed samples. Reduction in substrate particle size was found to affect the AFEX process and rate of hydrolysis as well. Implications of the stover particle size, composition, and inhibitory role of the phenolic fragments on an integrated biorefinery are discussed.

show abstract

“…9 Moreover, improved digestibility in less lignified immature grasses when compared with mature lignified plants has previously been demonstrated. 12 Additionally, studies by Lam et al 8 with 150 lines of forage grass (Phalaris aquatica) and the internodes of 100 lines of ryegrass (Lolium perenne) demonstrated that the hydroxycinnamic acid content was also important to explain the recalcitrance of such grasses.…”

Section: Introductionmentioning

confidence: 99%

Enzymatic hydrolysis of chemithermomechanically pretreated sugarcane bagasse and samples with reduced initial lignin content

Mendes

Siqueira

Carvalho

et al. 2011

Biotechnology Progress

View full text Add to dashboard Cite

Chemithermomechanical (CTM) processing was used to pretreat sugarcane bagasse with the aim of increasing cell wall accessibility to hydrolytic enzymes. Yields of the pretreated samples were in the range of 75-94%. Disk refining and alkaline-CTM and alkaline/sulfite-CTM pretreatments yielded pretreated materials with 21.7, 17.8, and 15.3% of lignin, respectively. Hemicellulose content was also decreased to some extent. Fibers of the pretreated materials presented some external fibrillation, fiber curling, increased swelling, and high water retention capacity. Cellulose conversion of the alkaline-CTM- and alkaline/sulfite-CTM-pretreated samples reached 50 and 85%, respectively, after 96 h of enzymatic hydrolysis. Two samples with low initial lignin content were also evaluated after the mildest alkaline-CTM pretreatment. One sample was a partially delignified mill-processed bagasse. The other was a sugarcane hybrid selected in a breeding program. Samples with lower initial lignin content were hydrolyzed considerably faster in the first 24 h of enzymatic digestion. For example, enzymatic hydrolysis of the sample with the lowest initial lignin content (14.2%) reached 64% cellulose conversion after only 24 h of hydrolysis when compared with the 30% observed for the mill-processed bagasse containing an initial lignin content of 24.4%.

show abstract

Chemical Composition and Enzymatic Degradability of Xylem and Nonxylem Walls Isolated from Alfalfa Internodes

Cited by 26 publications

References 44 publications

Topochemical distribution of lignin and hydroxycinnamic acids in sugar-cane cell walls and its correlation with the enzymatic hydrolysis of polysaccharides

Topochemical distribution of lignin and hydroxycinnamic acids in sugar-cane cell walls and its correlation with the enzymatic hydrolysis of polysaccharides

Effect of particle size based separation of milled corn stover on AFEX pretreatment and enzymatic digestibility

Enzymatic hydrolysis of chemithermomechanically pretreated sugarcane bagasse and samples with reduced initial lignin content

Contact Info

Product

Resources

About