Wood Chemistry, Fundamentals and Applications, Second Edition, examines the basic principles of wood chemistry and its potential applications to pulping and papermaking, wood and wood waste utilization, pulping by-products for production of chemicals and energy, and biomass conversion.

Wood chemistry: fundamentals and applications.

Extrusion as a pretreatment for lignocellulosic biomass: Fundamentals and applications

Bioethanol is a promising substitute for fossil fuels to alleviate the energy crisis. To improve the economic and environmental efficiency of bioethanol production from lignocellulosic biomass, the recycling techniques related to pretreatment, enzymatic hydrolysis, fermentation and distillation are discussed in the present study. The core of recycling technique is to recycle wastes and high-cost additives, including pretreatment waste liquor, stillage, solid residues after hydrolysis and fermentation, cellulases and yeast. On the one hand, the waste liquor can be reused as fresh water for the same or different conversion steps; on the other hand, wastes are the potential feedstocks for by-products production. As for high-cost additives, the most common approach is collecting for the next batch conversion. After adoption of recycling techniques, the consumption of water, chemicals, cellulases and yeast is reduced, which directly saves the conversion cost of lignocellulosic bioethanol. Meanwhile, high-value by-products and reduction of waste disposal indirectly increase economic and environmental efficiency. Besides, this review also provides the categories of wastes, influence factors of recycling, and the advantages and disadvantages of various recycling techniques. In order to resolve the drawbacks of toxics accumulation, low recycling efficiency and low economic feasibility in the existing recycling techniques, a novel recycling strategy that meets all-components utilization, non-wastes generation and high-cost additives recycling simultaneously is proposed. Moreover, the economic and environmental evaluation of recycling techniques on a pilot or industrial scale should be made more efforts in the future.

A review on recycling techniques for bioethanol production from lignocellulosic biomass

Bioethanol production from cellulosic hydrolysates by engineered industrial Saccharomyces cerevisiae

Effect of hydrothermal pretreatment on Miscanthus anaerobic digestion.

Alkaline twin-screw extrusion pretreatment of Miscanthus with recycled black liquor at the pilot scale

The development of rapeseed cultivars (Brassica napus L.) with high oleic acid and low linolenic acid is highly desirable for food and industrial applications. In this study, the Korean rapeseed cultivar Tamla was used for ethyl methanesulfonate (EMS)-induced mutagenesis and seed oils were screened up to generation M7 for high oleate mutants. Two mutant populations (M7) with an average of approximately 76% oleic acid content were isolated. Yield components between two mutant populations and untreated Tamla plants were not substantially different, although the mutants in the vegetative stage were slightly smaller in size than Tamla. Genomic analyses of six fatty acid desaturase (four FAD2 and two FAD6) genes revealed that the elevated oleic acid content in the mutants is the result of single gene mutations. Changes in DNA sequence were observed in two genes out of six fatty acid desaturase (four FAD2 and two FAD6). FAD2-2 exhibited a 2-bp deletion in the upstream region of the gene in the two mutants, resulting in a severely truncated polypeptide (57 aa instead of 469 aa), while six point mutations in the other gene did not result in changes in the amino acid sequence. Based on these results, FAD2-2, an endoplasmic reticulum (ER) oleic acid desaturase, is affected in the mutants, resulting in a ~ 7% increase in oleic acid content in comparison to untreated Tamla plants. The induced mutants could be utilized for the development of high oleic oil rapeseed varieties and for regulatory studies of lipid metabolism in seed oils.

EMS-induced mutation of an endoplasmic reticulum oleate desaturase gene (FAD2-2) results in elevated oleic acid content in rapeseed (Brassica napus L.)

Hydrothermal-process-based direct extraction of polydisperse lignin microspheres from black liquor and their physicochemical characterization

Camelina sativa L. is an emerging biodiesel crop with exceptional cold tolerance. We isolated two small hydrophobic proteins, CsRCI2A and CsRCI2E (rare cold inducible), from Camelina. The proteins displayed high homology with RCI2-related proteins from various species. CsRCI2A contained only two trans-membrane domains but CsRCI2E possessed both trans-membrane domains and a C-terminal tail. Subcellular localization of the two encoded proteins was detected in the plasma membrane and these proteins were induced by salinity stress at 0.2 M NaCl and cold stress at 2 °C. The two genes mediated an early defense to abiotic stresses dependant on the circadian clock. To understand the function of the CsRCI2 proteins, various combinational arrangements of the two genes were transformed into the yeast deletion mutant PMP3. CsRCI2A was able to complement the mutation in yeast under salinity stress (0.5 M NaCl), while CsRCI2E protein was not. However, a truncated version of the protein (CsRCI2E∆58) functionally complemented PMP3. Interestingly, the CsRCI2A+E swapped protein not able to complement to the degree of CsRCI2A, but complemented better than the CsRCI2E protein. A similar pattern was evident concerning restoration of membrane potential in hyperpolarization caused by deletion of PMP3. The results indicate different functions of the CsRCI2A and CsRCI2E proteins in plasma membrane potential regulation during salt stress. The CsRCI2 C-terminal hydrophilic tail likely has a suppressor function and the two hydrophobic domains likely are activators via maintenance of membrane potential.

CsRCI2A and CsRCI2E genes show opposite salt sensitivity reaction due to membrane potential control

Pretreatment to improve the enzymatic digestibility of highly crystallized lignocellulosic biomass is essential in biorefinery processes. This study investigates the combination of lignocellulose pretreatment with continuous alkaline single-screw extrusion and ultrasonication for biosugar production. Miscanthus sacchariflorus was used because it is a promising bioenergy crop. The results show that ultrasonication with continuous alkaline pretreatment increased the enzymatic digestibility of carbohydrates and reduced the use of chemicals during pretreatment. An hour of ultrasonication following 0.2 M NaOH (2.25 mol-NaOH/kg-biomass) continuous alkaline pretreatment resulted in a 6.7% increase in total biosugar production (83.1% of theoretical yield), a decrease of up to 26.1% in chemical usage, and a 17.0% increase in lignin removal compared with the case without ultrasonication. The developed method can be considered an effective and eco-friendly approach to the production of bio-based materials.

https://www.mdpi.com/1996-1073/13/21/5636/pdf

Ji-Eun Lee

Papers

Alkaline twin-screw extrusion pretreatment of Miscanthus with recycled black liquor at the pilot scale

EMS-induced mutation of an endoplasmic reticulum oleate desaturase gene (FAD2-2) results in elevated oleic acid content in rapeseed (Brassica napus L.)

Hydrothermal-process-based direct extraction of polydisperse lignin microspheres from black liquor and their physicochemical characterization

CsRCI2A and CsRCI2E genes show opposite salt sensitivity reaction due to membrane potential control

Lignocellulose Pretreatment Combining Continuous Alkaline Single-Screw Extrusion and Ultrasonication to Enhance Biosugar Production