Targeting hydroxycinnamoyl CoA: shikimate hydroxycinnamoyl transferase for lignin modification in Brachypodium distachyon.

Background: Hydroxycinnamoyl CoA: shikimate hydroxycinnamoyl transferase (HCT) is a central enzyme of the so-called "esters" pathway to monolignols. As originally envisioned, HCT functions twice in this pathway, to form coumaroyl shikimate and then, in the "reverse" direction, to convert caffeoyl shikimate to caffeoyl CoA. The discovery of a caffeoyl shikimate esterase (CSE) that forms caffeic acid directly from caffeoyl shikimate calls into question the need for the reverse HCT reaction in lignin biosynthesis.

Allelopathic effects of exogenous phenylalanine: a comparison of four monocot species.

Exogenous phenylalanine stunted annual ryegrass but not switchgrass or winter grain rye, with deuterium incorporation up to 3% from phenyalanine-d . Toxicity to duckweed varied with illumination intensity and glucose uptake. Isotopic labeling of biomolecules through biosynthesis from deuterated precursors has successfully been employed for both structural studies and metabolic analysis.

Effect of lignin content on changes occurring in poplar cellulose ultrastructure during dilute acid pretreatment.

Background: Obtaining a better understanding of the complex mechanisms occurring during lignocellulosic deconstruction is critical to the continued growth of renewable biofuel production. A key step in bioethanol production is thermochemical pretreatment to reduce plant cell wall recalcitrance for downstream processes. Previous studies of dilute acid pretreatment (DAP) have shown significant changes in cellulose ultrastructure that occur during pretreatment, but there is still a substantial knowledge gap with respect to the influence of lignin on these cellulose ultrastructural changes.

High shear homogenization of lignin to nanolignin and thermal stability of nanolignin-polyvinyl alcohol blends.

A new method to prepare nanolignin using a simple high shear homogenizer is presented. The kraft lignin particles with a broad distribution ranging from large micron- to nano-sized particles were completely homogenized to nanolignin particles with sizes less than 100 nm after 4 h of mechanical shearing. The (13) C nuclear magnetic resonance (NMR) and (31) P NMR analysis showed that there were no major changes in the chemical composition between the starting kraft lignin particles and the nanolignin obtained after 4 h of mechanical treatment.

Cellulose Isolation Methodology for NMR Analysis of Cellulose Ultrastructure.

In order to obtain accurate information about the ultrastructure of cellulose from native biomass by C cross polarization magic angle spinning (CP/MAS) NMR spectroscopy the cellulose component must be isolated due to overlapping resonances from both lignin and hemicellulose. Typically, cellulose isolation has been achieved via holocellulose pulping to remove lignin followed by an acid hydrolysis procedure to remove the hemicellulose components. Using C CP/MAS NMR and non-linear line-fitting of the cellulose C₄ region, it was observed that the standard acid hydrolysis procedure caused an apparent increase in crystallinity of ~10% or less on the cellulose isolated from Populus holocellulose.

Increase in 4-coumaryl alcohol units during lignification in alfalfa (Medicago sativa) alters the extractability and molecular weight of lignin.

The lignin content of biomass can impact the ease and cost of biomass processing. Lignin reduction through breeding and genetic modification therefore has potential to reduce costs in biomass-processing industries (e.g.

Enhanced enzymatic hydrolysis of spruce by alkaline pretreatment at low temperature.

Alkaline pretreatment of spruce at low temperature in both presence and absence of urea was studied. It was found that the enzymatic hydrolysis rate and efficiency can be significantly improved by the pretreatment. At low temperature, the pretreatment chemicals, either NaOH alone or NaOH-urea mixture solution, can slightly remove lignin, hemicelluloses, and cellulose in the lignocellulosic materials, disrupt the connections between hemicelluloses, cellulose, and lignin, and alter the structure of treated biomass to make cellulose more accessible to hydrolysis enzymes.