Relationships between Cell Wall Digestibility and Lignin Content as Influenced by Lignin Type and Analysis Method

Abstract

Difficulties in measuring the lignin content of forage and biomass crops confounds efforts by plant breeders and molecular biologists to grasp how shifts in lignin chemistry affect fiber digestibility. In this study, relationships between digestibility and lignin content were examined by artificially lignifying Zea mays L. cell walls with bulk polymers composed of p‐hydroxyphenyl‐guaiacyl (HG) and guaiacyl (G) units or with endwise polymers composed of G, guaiacyl‐syringyl (GS), and guaiacyl‐syringyl‐p‐coumaric acid (GSpCA) units. Regressions of in vitro rumen gas production or nonfermented polysaccharides (NFP) vs. lignin content accurately measured by an indirect spectrophotometric method revealed that G‐bulk and especially syringyl (S)‐rich endwise polymers were the least inhibitory to digestion. While providing biased estimates at low lignin contents, the acetyl bromide‐soluble lignin (ABSL) assay correctly ranked how endwise polymers affected the digestibility of highly lignified cell walls, but the method required unique absorption coefficients to assess relationships for bulk polymers. Conversely, the Klason lignin (KL) method provided more accurate estimates at low lignin contents, but varying recovery of KL among lignin types created bias for highly lignified cell walls. Overall, our results indicate that S‐rich lignins are the least inhibitory to digestion, but detecting desirable shifts in lignin chemistry will require the judicious use of several analytical methods.

Functional Lignin‐based Polymers: Isolation, Synthetic Methods and High‐valued Applications

“…Here, we introduced some common methods used for the separation and purification of lignin, which included acid extraction, alkali extraction, enzyme extraction, oxidation/reduction extraction, high boiling alcohol solvent extraction, organic solvent extraction, ionic liquid extraction, supercritical extraction, molten salt extraction, low eutectic solvent extraction, etc. [28][29][30][31][32] The features of various separation methods were summarized in Table 1.…”

“…Here, the isolation of lignin can be divided into three categories: (1) The other components in the plant fibers are dissolved and removed, and the lignin residues as insoluble components are filtered out; (2) As a soluble component, lignin is dissolved first by chemical agents, and other components (cellulose, hemicellulose) are mainly retained as solid residues; (3) The complete separation and conversion of all lignocellulosic components by one‐pot chemical catalytic treatment. Here, we introduced some common methods used for the separation and purification of lignin, which included acid extraction, alkali extraction, enzyme extraction, oxidation/reduction extraction, high boiling alcohol solvent extraction, organic solvent extraction, ionic liquid extraction, supercritical extraction, molten salt extraction, low eutectic solvent extraction, etc [28–32] . The features of various separation methods were summarized in Table 1.…”

Teor de sacarose, acúmulo de lignocelulose, dimensionamento celular e digestibilidade >i<in vitro>/i< de entrenós de cana-de-açúcar em relação ao estágio de maturação e a genótipos de >i<Saccharum>/i< spp

“…A lignina e os ácidos hidroxicinâmicos: ferúlico e paracumárico, também são drenos de carbono fotossintético (FRANK et al, 2004, HALPIN, 2019. A lignina e os ácidos hidroxicinâmicos são sintetizados a partir da fenilalanina produzida na via de síntese de chiquimato (HERRMANN et al, 1995;GRABBER, 2019). A conversão de frutose-1,6bifostato em fosfoenolpiruvato durante a glicólise, e a síntese de fenilalanina a partir de fosfoenolpiruvato e eritrose-4-fosfato são etapas essenciais para a síntese de lignina e ácidos hidroxicinâmicos (VANHOLME et al, 2010, VANHOLME et al, 2019.…”

“…Marcadores moleculares específicos para discriminar essas características poderiam auxiliar no desenvolvimento de genótipos de cana-de-açúcar com aptidão dupla, ou seja, alto rendimento de sacarose e baixa recalcitrância de lignocelulose Introdução O sucesso da industrialização da conversão da biomassa em polímeros majoritários como a celulose, hemiceluloses e lignina, depende de pré-tratamentos químicos economicamente viáveis e da conversão eficiente desses polímeros majoritários em combustíveis e produtos químicos de alto valor agregado (GUO;SONG, 2019;HOLVERDA et al, 2019). A maior parte da biomassa vegetal disponível para o bioprocessamento está contida nas paredes celulares secundárias das plantas vasculares (YANG et al, 2013).…”