Forest Sciences Commons^™

Characterization Of Lignin Structural Variability And The Associated Application In Genome Wide Association Studies, Nathan D. Bryant

Doctoral Dissertations

Poplar (Populus sp.) is a promising biofuel feedstock due to advantageous features such as fast growth, the ability to grow on marginal land, and relatively low lignin content. However, there is tremendous variability associated with the composition of biomass. Understanding this variability, especially in lignin, is crucial to developing and implementing financially viable, integrated biorefineries. Although lignin is typically described as being comprised of three primary monolignols (syringyl, guaiacyl, p-hydroxyphenyl), it is a highly irregular biopolymer that can incorporate non-canonical monolignols. It is also connected by a variety of interunit linkages, adding to its complexity. Secondary cell wall …

Development Of Hydrophobic Paper And Wood Products Via Metal Ion Modification, Oshani Nayanathara Rathnayaka Mudiyanselage

Theses and Dissertations

Renewable lignocellulosic materials are promising green plastic alternatives to fossil fuel-based plastics. However, the hydrophilic nature and poor water resistance of lignocellulosic materials have hindered their practical applications. This study reports a facile metal-ion-modification (MIM) route, swelling with aqueous metal ion solutions, and drying to convert conventional hydrophilic paper and wood pulp into biodegradable hydrophobic paper and tableware without the addition of hydrophobic sizing chemicals/materials. Metal ions such as Fe3+ and Zr4+ can coordinate with pulp fibers’ polar groups (i.e., O.H., C=O, and COOH) that induce self-assembly of their surface fibrillated “hairy” cellulose nanofibrils to form a more compact structure …

Application Of Mass Spectrometry For Characterization Of Plant-Based Phenolics And Alkaloids, Masoumeh Dorrani

Theses and Dissertations--Chemistry

Plant-derived compounds have the potential to produce value-added compounds with a variety of applications. For example, the lignin part of the lignocellulosic biomass, produced in large quantities as waste from the paper and pulp industries, is a rich source of phenolics with potential applications in the renewable energy sector, pharmaceutical, and chemical industries. On the other hand, plant alkaloids are the primary source for developing plant-derived therapeutics. Unfortunately, the recalcitrant nature of plant cell walls, low extraction yields of small secondary metabolites, and the lack of effective analytical methods for a rapid and accurate identification of plant-based compounds and plant’s …

Recovering And Upgrading Kraft Lignin For Application In Flexible Polyurethane Foam, Peng Quan

Dissertations, Master's Theses and Master's Reports

Lignin is the second abundant natural polymer and has been highlighted as a potential substitute for fossil-based raw materials. However, the inherent molecular heterogeneity and the complex recovery processes result in the challenge of controlling the molecular properties and value-added applications of lignin in large scale. To address those issues, a novel acid-liquefaction process was developed in this study to recover Kraft lignin with improved molecular homogeneity directly from black liquor.

In the first study, the liquefaction parameters were screened based on yield and molecular weight properties of the recovered lignin. Then, the recovered lignin samples were used to replace …

Corrigendum: Bel1-Like Homeodomain Protein Blh6a Is A Negative Regulator Of Cald5h2 In Sinapyl Alcohol Monolignol Biosynthesis In Poplar (Front. Plant Sci., (2021), 12, (695223), 10.3389/Fpls.2021.695223), Qiao Wang, Xinren Dai, Hongying Pang, Yanxia Cheng, Xiong Huang, Hui Li, Xiaojing Yan, Fachuang Lu, Hairong Wei, Ronald R. Sederoff, Quanzi Li

Michigan Tech Publications

When originally published, the article title contained a typographical error. The correct gene name should be “CAld5H2” instead of “CAl5H2” as originally published. The correct title is “BEL1-like Homeodomain Protein BLH6a is a Negative Regulator of CAld5H2 in Sinapyl Alcohol Monolignol Biosynthesis in Poplar.” The authors state that this does not change the scientific conclusions of the article in any way. The original article has been updated.

Degumming Of Hemp Fibers Using Combined Microwave Energy And Deep Eutectic Solvent, Bulbul Ahmed

LSU Master's Theses

Hemp is considered as one of the sustainable agricultural fiber materials. Degumming or surface modification of hemp bast is needed to produce single fibers for ensuing textile and industrial applications. The traditional degumming process necessitates a high amount of alkali, which causes detrimental environmental pollution. This study offers a new method to degum hemp fibers with reduced use of harmful alkali and precious water resources. In this work, hemp bast fibers were degummed by using combined microwave energy and deep eutectic solvent (DES). The properties of hemp fibers manufactured by this method were investigated and compared with the traditional alkali …

Bel1-Like Homeodomain Protein Blh6a Is A Negative Regulator Of Cal5h2 In Sinapyl Alcohol Monolignol Biosynthesis In Poplar, Qiao Wang, Xinren Dai, Hongying Pang, Yanxia Cheng, Xiong Huang, Hui Li, Hairong Wei, Et. Al.

Michigan Tech Publications

Lignin is one of the major components of xylem cell walls in tree stems. The lignin in the wood of most flowering plants (dicotyledonous angiosperms) is typically polymerized from three monolignol precursors, coniferyl alcohol, sinapyl alcohol, and p-coumaroyl alcohol, resulting in guaiacyl (G), syringyl (S), and hydroxyphenyl (H) subunits, respectively. In this study, we focus on the transcriptional regulation of a coniferaldehyde 5-hydroxylase (CAld5H2) gene, which encodes a key enzyme for sinapyl alcohol biosynthesis. We carried out a yeast one-hybrid (Y1H) screen to identify candidate upstream transcription factors (TFs) regulating CAld5H2. We obtained 12 upstream TFs …

Multivariate Statistical Analyses For Studying Kenaf Germination, Growth, And Fiber Production Under Salinity Constraint, Rekaya Ayadi, Rayda Ben Ayed, Nejla Lassoued, Hichem Ben Salem, Mohamed Larbi Khouja, Lamia Hamrouni, Mohsen Hanana

Turkish Journal of Agriculture and Forestry

It is due to the lack of renewable fiber sources for industrial purposes that the need for finding available and alternative material has become imperative. Kenaf (Hibiscus cannabinus L.), a fast-growing industrial crop, would be a potential solution for valorizing salinized lands and/or soils irrigated with saline water. With the aim of selecting and valorizing salt-tolerant species with high fiber yields and industrial values, we launched the assessment of the performance of kenaf culture (var. Guangdong 743-2) under salinity constraints. Germination and vegetative stages were considered in the present study to better evaluate the whole life cycle of the species. …

Variation In Secondary Metabolites Contents Of Spinoso Sardo Artichoke (Cynara Cardunculus L.) Under Different Day Lengths, Angela Fadda, Adriana Virdis, Antonio Barberis, Sara Melito

Turkish Journal of Agriculture and Forestry

Globe artichoke (Cynara cardunculus L. var. scolymus Fiori) is an economically important crop in the Mediterranean basin and particularly in Italy, which is a leading producer. In this research, we studied the effect of extended photoperiod (15 and 17 h) on polyphenolic, flavonoids, lignin concentrations, and antioxidant activity in edible and inedible organs of artichoke. The influence of day length on morphological traits and biomass accumulation was also assessed. The total phenolic content of whole plants grown under natural day length conditions exceeds that of photoperiod extended for 15 and 17 h by 31% and 32.4%, respectively. The decrease of …

Elevated Co2 Induced Changes In The Chemistry Of Quaking Aspen (Populus Tremuloides Michaux) Leaf Litter: Subsequent Mass Loss And Microbial Response In A Stream Ecosystem, Steven Rier, Nancy Tuchman, Robert Wetzel, James Teeri

Nancy Tuchman

No abstract provided.

Lignin Decomposition Is Sustained Under Fluctuating Redox Conditions In Humid Tropical Forest Soils, Steven J. Hall, Whendee L. Silver, Vitaliy I. Timokhin, Kenneth E. Hammel

Steven J. Hall

Lignin mineralization represents a critical flux in the terrestrial carbon (C) cycle, yet little is known about mechanisms and environmental factors controlling lignin breakdown in mineral soils. Hypoxia is thought to suppress lignin decomposition, yet potential effects of oxygen (O2) variability in surface soils have not been explored. Here, we tested the impact of redox fluctuations on lignin breakdown in humid tropical forest soils during ten-week laboratory incubations. We used synthetic lignins labeled with 13C in either of two positions (aromatic methoxyl or propyl side chain Cb) to provide highly sensitive and specific measures of lignin mineralization seldom employed in …

Improving Alternate Lignin Catabolite Utilization Of Ligab From Sphingobium Sp. Strain Syk-6 Through Site Directed Mutagenesis, Kevin P. Barry, Erin F. Cohn, Abraham Ngu, Erika A. Taylor

Erika A. Taylor, Ph.D.

Protocatechuate 4,5-dioxygenase (LigAB) catalyzes dioxygenation of multiple lignin derived aromatic compounds—such as protocatechuate (PCA), gallate (GA) and 3-O-methyl gallate (3OMG)—with decreasing proficiency as the molecule size increases. We predicted that phenylalanine-103 of the α subunit (Phe103α) controls substrate specificity through interaction with the C5-funtionality of bound substrates, and mutagenesis would enhance GA and 3OMG catalysis. LigAB with Phe103α mutations (F103 V, F103T and F103H) displayed enhanced catalytic efficiency for dioxygenation of 3OMG, with mutants displaying 12- to 31-fold increases in View the MathML source, making these mutant enzymes more active with 3OMG than its native dioxygenase (DesZ). The F103T and …

Production And Applications Of Formaldehyde-Free Phenolic Resins Using 5-Hydroxymethylfurfural Derived From Glucose In-Situ, Yongsheng Zhang

Electronic Thesis and Dissertation Repository

The phenol-formaldehyde (PF) resin manufacturing industry is facing a growing challenge with respect to concerns over human health, due to the use of carcinogenic formaldehyde and sustainability due to the use of petroleum-based phenol in PF resin manufacture. Glucose and its derivative, 5-hydroxymethylfurfural (5-HMF), have proven to be potential substitutes for formaldehyde in the synthesis of phenolic novolac resins.

This thesis investigated a number of glucose and 5-HMF resin systems including the curing of phenol-glucose novolac resin (PG) with a bis-phenol-A type epoxy. The curing process was modeled according to the Sestak-Berggren equation (S, B) using Málek methods. This was …

Maximizing Lignin Yield Using Experimental Design Analyzing The Impact Of Solvent Composition And Feedstock Particle Size On The Organosolv Process In The Presence Of Feedstock Contamination, Hagen Maraun

Masters Theses

The depletion of fossil feedstock and the unfavorable environmental effects accompanying by its exploitation are the driving forces in the process of transitioning to renewable feedstock as the primary resource. Similar to petrorefineries, a new modern biorefinery would use biomass to produce a variety of different chemical products and transportation fuels. Lignin, a potential low-cost, high volume output process stream derived from lignocellulosic biomass is currently being researched to better support the economics of the future biorefinery. In this study, experimental design was used to determine the optimal level for each process factor in an organosolv fractionation process that targets …

Characterizing The Promiscuity Of Ligab, A Lignin Catabolite Degrading Extradiol Dioxygenase From Sphingomonas Paucimobilis Syk-6, Kevin P. Barry, Erika A. Taylor

Erika A. Taylor, Ph.D.

LigAB from Sphingomonas paucimobilis SYK-6 is the only structurally characterized dioxygenase of the largely uncharacterized superfamily of Type II extradiol dioxygenases (EDO). This enzyme catalyzes the oxidative ring-opening of protocatechuate (3,4-dihydroxybenzoic acid or PCA) in a pathway allowing the degradation of lignin derived aromatic compounds (LDACs). LigAB has also been shown to utilize two other LDACs from the same metabolic pathway as substrates, gallate, and 3-O-methyl gallate; however, kcat/KM had not been reported for any of these compounds. In order to assess the catalytic efficiency and get insights into the observed promiscuity of this enzyme, steady-state kinetic analyses were performed …

Nitrogen Deposition Effects On Production And Decomposition Of Coarse Woody Debris, Bethany Jeanne Lyons

Dissertations, Master's Theses and Master's Reports - Open

Atmospheric nitrogen deposition has the potential to impact forest productivity, microbial associations, nutrient cycling, decomposition and stand dynamics. However, among the least studied aspects of these processes are the production and decomposition of dead woody biomass, or coarse woody debris (CWD). Coarse woody debris is made up of dead woody material on the ground called down dead wood (DDW) and dead standing trees which are often referred to as snags. Observed reductions in decomposition of CWD have been linked to substrate quality and microbial communities. If the decomposition effect is ubiquitous among litter types, CWD density, C:N, and biomass are …

Litter Decomposition Of Picea Orientalis, Pinus Sylvestris And Castanea Sativa Trees Grown In Artvin In Relation To Their Initial Litter Quality Variables, Temel Sariyildiz

Turkish Journal of Agriculture and Forestry

The aim of the present study was to determine the effects of the litter chemistry of spruce (Picea orientalis), pine (Pinus sylvestris) and chestnut (Castanea sativa) grown in the Artvin region on their decomposition rates. Freshly fallen litters from these species were analysed for total carbon, nitrogen, lignin, cellulose and hemicellulose. The litterbag technique was used to determine their mass loss in the field for 2 years. At intervals of 6, 12, 18 and 24 months, 5 litterbags of each species were collected and returned to the laboratory and then analysed for their mass losses. The results showed that differences …

Lignin Distribution In Thermomechanically Pulped Wood Fibers Via X-Ray Microanalysis, Douglas Stokke, Xuerong Wang

Douglas D. Stokke

The three major framework organic constituents of the secondary xylem (wood) of trees are cellulose, hemicelluloses, and lignin. Lignin imparts a number of important physical properties to the woody cell wall. In addition, lignin serves as the "cement" which binds cells together, and is the material which must be softened, altered, or removed during pulping processes. The distribution of lignin within pulp cell walls is of importance with respect to use of the pulp fibers. In this study, x-ray analysis was used to investigate lignin distribution in thermomechanically pulped (i.e., pulped with heat and pressure, with no chemical treatment) aspen …

Tb41: The Potential Of Lignin Research, Norman P. Kutscha, James R. Gray

Technical Bulletins

Lignin constitutes a vast natural resource, which can be found in various forms depending on where it is obtained and how it is isolated. To most easily isolate lignin, we must understand more thoroughly its chemical structure and how it is bound to the other wall components. To use lignin more effectively and develop new uses for it, we must understand its properties. Likewise, the most effective use of lignin-containing materials such as wood and wood products depends on understanding how their properties are affected by the properties of lignin.