Structural Characterization of Lignin in Four Cacti Wood: Implications of Lignification in the Growth Form and Succulence

Wood lignin composition strongly depends on anatomical features and it has been used as a marker for characterizing major plant groups. Wood heterogeneity in Cactaceae is involved in evolutionary and adaptive processes within this group; moreover, it is highly correlated to the species growth form. Here we studied the lignin structure from different types of woods in four Cactaceae species with different stem morphologies (Pereskia lychnidiflora, tree/fibrous wood; Opuntia streptacantha and Pilosocereus chrysacanthus, tree/succulent fibrous wood; Ferocactus hamatacanthus, cylindrical stem/dimorphic wood) in order to determine their relationship with the wood anatomy in an evolutionary-adaptive context. Dioxane lignin was isolated and analyzed by pyrolysis coupled with gas chromatography and mass spectrometry (Py-GC/MS), two-dimensional nuclear magnetic resonance spectroscopy (2D-NMR) and attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR). The main linkages are the β-O−4′ ether (67–85%), the β-β′ resinol (10–26%) and the β-5′ and α-O−4′ linkages of the phenylcoumaran structures (≤7%). Spirodienone structures have a considerable abundance (5%) in the dimorphic wood of F. hamatacanthus. In addition, low contents (≤3%) of α,β-diaryl ether, α-oxidized β-O−4′ ether and dibenzodioxocin structures were found. The sinapyl- and coniferyl acetates are not part of the wood lignin in any of the studied species. The low (≤5%) γ-acetylation in the F. hamatacanthus and P. chrysacanthus wood lignin is here interpreted as an evidence of a high specialization of the wood elements in the conduction/storage of water. The lignin of the studied Cactaceae is composed predominantly of guaiacyl and syringyl units (S/G: 0.9–16.4). High abundance of syringyl units (62–94%) in three of the four species is considered as a defense mechanism against oxidative agents, it is a very conspicuous trait in the most succulent species with dimorphic wood. Furthermore, it is also associated with ferulates and the herein called γ-acetylated guaiacyl-syringaresinol complexes acting as nucleation sites for lignification and as cross-links between lignin and carbohydrates at the wide-band tracheid-fiber junctions

Celulosa y microcelulosa de residuos del cultivo de caña de azúcar (Saccharum spp.)

Objective: To characterize the structure, texture and thermal properties of cellulose and cellulose microfibers (MFC) of three sugarcane crops and the development of a biocomposite. Design / methodology / approach: The celluloses were extracted by the Kraft method and the MFCs of the cultures MEX-69-290, CP-72-2086 and MEX-68-P23, using oxidative and mechanical processes; for its characterization spectroscopic, microscopic and thermal techniques were used; and were analyzed with a completely randomized design, where the treatments were cellulose and CFM extracted from the three cultivars of sugarcane; In addition to the fusion processing of a biocomposite from polylactic acid and CMF. Results: Cellulose and CFM were obtained from the straw of the three crops, the similar quality, the percentage of moisture in the straw and the cellulose having the same behavior, the chemical composition of the cellulose is of high purity. The results of XRD and FTIR have characteristic bands and similar amounts of cellulose in the crystalline phase. TGA indicates that cellulose decomposes at higher temperatures of polylactic acid (PLA), which supports melt mixing processes. Limitations of the study / implications: The varieties of sugarcane pajamas have different characteristics in the cellulose phase and in the CFM phase; but similar between cultivars. Findings / conclusions: The crystallinity by XRD and the identification of functional groups by FTIR show us characteristic bands of the cell in the crystalline phase and how the amorphous part of the straw is lost without treatment, becoming more crystalline when it becomes cellulose and mostly in microcellulose; as well as the similarity that exists in the three cultivars of said components and in similar quantities. The resistance properties of the biocomposite will be affected when the CFMs are added to the polylactic acid.Objetivo: Caracterizar la estructura, textura y propiedades térmicas de celulosas y microfibras de celulosa (MFC) de tres cultivares de caña de azúcar y la elaboración de un biocompuesto. Diseño/metodología/aproximación: Las celulosas fueron extraídas por el método Kraft y las MFC de los cultivares MEX-69-290, CP-72-2086 y MEX-68-P23, utilizando procesos oxidativos y mecánicos; para su caracterización se emplearon técnicas espectroscópicas, microscópicas y térmicas; y fueron analizadas con un diseño completamente al azar, donde los tratamientos fueron la celulosa y MFC extraídas de los tres cultivares de caña de azúcar; además de la elaboración por fusión de un biocompuesto a partir de ácido poliláctico y las MCF. Resultados: Se obtuvieron celulosa y MFC de la paja de los tres cultivares, la cual presentó similitud, teniendo el mismo comportamiento el porcentaje de humedad en la paja y la celulosa, la composición química de la celulosa es de alta pureza. Los resultados de XRD y FTIR presentan bandas características y cantidades similares de celulosa en fase cristalina. TGA indica que la celulosa se descompone a temperaturas más altas de ácido poliláctico (PLA), lo que apoya los procesos de mezcla en fusión. Limitaciones del estudio/implicaciones: Las variedades de paja de caña de azúcar presentan características diferentes en la fase de celulosa y en fase de MFC; pero similar entre cultivares. Hallazgos/conclusiones: La cristalinidad mediante XRD y la identificación de grupos funcionales por FTIR nos muestran bandas características de celulosa en fase cristalina y cómo se va perdiendo la parte amorfa de la paja sin tratamiento, volviéndose más cristalina al convertirse en celulosa y mayormente en microcelulosa; así como también la similitud que existe en las tres cultivares de dichos componentes y en cantidades semejantes. Las propiedades de resistencia del biocompuesto se vieron afectadas cuando las MFC´s se agregaron al ácido poliláctico

Bioplastics: Environment-friendly materials and their production technologies: Bioplastics: friendly materials with the environment and production technologies

Objective: To analyze the general definition of bioplastics from their contribution to the solution of environmental problems due to plastic contamination; learn about obtaining and processing technologies, as well as biodegradation. Design/methodology/approach: A documentary research was carried out from 2010 to 2022, concerning the definitions of plastics and bioplastics by various authors, their sources of production and processing technologies to obtain final products. Likewise, the practices that have been applied for its final disposal and/or reuse. Emphasis will be placed on the production of more environ-mentally friendly plastics based on polylactic acid (PLA), which is one of the most widely used biodegradable materials today. Results: There is a potential and growing use of vegetable fibers and other biological materials suitable for processing bioplastics in a sustainable way. In Mexico, there is a large amount of vegetable waste to be used, and thus obtain biodegradable and less polluting materials, with the advantage of degrading in less time than conventional plastics as a productive activity in the agro-industrial sector. To do this, it is necessary to process fibers or local plant residues to integrate them into said production of bioplastics. Limitations on study/implications: Limitarions are adjusted according to the literature cited. Findings/conclusions: In Mexico there are various sources of waste plant material, which provides a favorable field to be used in the production of plastics with less potential for contamination and greater capacity to biodegrade, adjusting to trends currently re-quired by demand. of plastics for packaging.Objective: To analyze the recent contributions of bioplastics in addressing environmental problems caused by plastic pollution. Design/Methodology/Approach: A literature review was carried out on the definitions of plastics and bioplastics, the sources of raw materials, processing technologies and methods to assess biodegradation. Current practices for final disposal and/or reuse were also examined. Special emphasis was placed on polylactic acid (PLA), one of the most widely used biodegradable materials today. Results: Over the years, there have been significant developments in the definitions of plastics and bioplastics, as well as in the sources of raw materials and processing technologies used to create final plastic products. By using bioplastics instead of conventional plastics, it is possible to reduce the dependence on petroleum and mitigate the pollution associated with plastic production and disposal. Furthermore, the enhanced biodegradability of bioplastics ensures that they break down more readily in natural environments, reducing the accumulation of plastic waste and its detrimental impact on ecosystems. The production of bioplastics using plant fibers, biological materials, and polymeric waste materials presents an opportunity for integration into the productive activities of the agro-industrial sector. This integration brings several benefits and synergies between agriculture and industry. Study limitations/Implications: We provide a report based on the literature. Findings/Conclusions: there is a notable current trend in the utilization of bioplastics as a viable substitute for conventional plastics. In order to assess the biodegradability and compostability of these materials, specific testing and certification standards have been established by reputable organizations. These standards serve as a reliable framework for evaluating the environmental impact and degradation characteristics of bioplastics. By adhering to these guidelines, manufacturers can ensure that their bioplastic products meet the necessary criteria for sustainable use

Wood Chemical Composition in Species of Cactaceae: The Relationship between Lignification and Stem Morphology

<div><p>In Cactaceae, wood anatomy is related to stem morphology in terms of the conferred support. In species of cacti with dimorphic wood, a unique process occurs in which the cambium stops producing wide-band tracheids (WBTs) and produces fibers; this is associated with the aging of individuals and increases in size. Stem support and lignification have only been studied in fibrous tree-like species, and studies in species with WBTs or dimorphic wood are lacking. In this study, we approach this process with a chemical focus, emphasizing the role of wood lignification. We hypothesized that the degree of wood lignification in Cactaceae increases with height of the species and that its chemical composition varies with wood anatomy. To test this, we studied the chemical composition (cellulose, hemicellulose, and lignin content) in 13 species (2 WBTs wood, 3 dimorphic, and 8 fibrous) with contrasting growth forms. We also analyzed lignification in dimorphic and fibrous species to determine the chemical features of WBTs and fibers and their relationship with stem support. The lignin contents were characterized by Fourier transform infrared spectroscopy and high performance liquid chromatography. We found that 11 species have a higher percentage (>35%) of lignin in their wood than other angiosperms or gymnosperms. The lignin chemical composition in fibrous species is similar to that of other dicots, but it is markedly heterogeneous in non-fibrous species where WBTs are abundant. The lignification in WBTs is associated with the resistance to high water pressure within cells rather than the contribution to mechanical support. Dimorphic wood species are usually richer in syringyl lignin, and tree-like species with lignified rays have more guaiacyl lignin. The results suggest that wood anatomy and lignin distribution play an important role in the chemical composition of wood, and further research is needed at the cellular level.</p></div

Chemical composition of lower wood in mature individuals of thirteen species of Cactaceae.

<p>The contents are reported in the total dry weight percent (% w/w). The standard deviation in each case was less than 10% on average.</p><p>(<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0123919#pone.0123919.s004" target="_blank">S1 Table</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0123919#pone.0123919.s003" target="_blank">S3 Dataset</a>. Supporting information for the S/G ratios)</p><p>* Species where the content of lignin in the lower wood was different between adult individuals, the difference in the lignin content in adults of F. pilosus was ≈ 19% and in E. platyacanthus was ≈ 23%, the other components of the wood vary proportionately. Moreover, in these dimorphic species occurs a change from WBTs wood in juvenile stages to fibrous wood in the mature ones.</p><p>Chemical composition of lower wood in mature individuals of thirteen species of Cactaceae.</p

Relationship between plant species size and percentage of syringyl lignin.

<p>Each dot represents the species size given in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0123919#pone.0123919.s005" target="_blank">S2 Table</a>.</p

Characteristics of individuals studied from thirteen species of Cactaceae, the regions of wood that were studied are indicated.

<p><b>Abbreviations.</b> Tuberculated (T), ribbed (R), tuberculated ribs (TR). Lower wood (LW): near to the vascular cambium (LWc), near to the pith (LWp). Upper wood (UW).</p><p>* In these dimorphic species occurs a change from WBTs wood in juvenile stages to fibrous wood in the mature ones.</p><p>Characteristics of individuals studied from thirteen species of Cactaceae, the regions of wood that were studied are indicated.</p

Fibrous wood in species of Cactaceae, cross sections, near the vascular cambium.

<p>Vessels embedded in a matrix of fibers with lignified rays except <i>Opuntia streptacantha</i>. (A) <i>Cylindropuntia imbricata</i>; (B) <i>Lophocereus marginatus</i>; (C) <i>Myrtillocactus geometrizans</i>; (D) <i>Opuntia streptacantha</i>: wood with vessels embedded in a matrix of fiber or parenchyma with intermixed WBTs and non lignified rays; (E) <i>Pereskia lychnidiflora</i>; (F) <i>Stenocereus dumortieri</i>. Bar is 200 μm; r = ray.</p

Non fibrous wood in species of Cacteae, cross sections near the vascular cambium.

<p>(A) <i>Ariocarpus retusus</i>: less lignified wood with vessels embedded in a matrix of WBTs separated by non lignified dilated rays; (B) <i>Coryphantha clavata</i>: wood with vessels embedded in a matrix of WBTs and narrow non lignified rays; (C) <i>Echinocactus platyacanthus</i>: wood with vessels embedded in a matrix of fibers and axial parenchyma with wider lignified rays; (D) <i>Ferocactus hamatacanthus</i>: wood with vessels embedded in a matrix of WBTs and fibers in similar proportions and a few narrow non lignified rays; (E) <i>Ferocactus pilosus</i>: wood with vessels embedded in a matrix of WBTs and lignified rays near the pith; (F) <i>Ferocactus pilosus</i>: wood with vessels embedded in a matrix of fibers and non lignified rays near the vascular cambium. Bar is 550 μm in A, B; 200 μm in C, E, F; 100 μm in D; r = ray.</p