Cellulose biosynthesis: current views and evolving concepts

Research Progress on Mechanical Strength of Rice Stalks

As one of the most important food crops in the world, rice yield is directly related to national food security. Lodging is one of the most important factors restricting rice production, and the cultivation of rice varieties with lodging resistance is of great significance in rice breeding. The lodging resistance of rice is directly related to the mechanical strength of the stalks. In this paper, we reviewed the cell wall structure, its components, and its genetic regulatory mechanism, which improved the regulatory network of rice stalk mechanical strength. Meanwhile, we analyzed the new progress in genetic breeding and put forward some scientific problems that need to be solved in this field in order to provide theoretical support for the improvement and application of rice breeding.

Self-flocculation behaviour of cellulose-based bioflocculant synthesized from sewage water grown Chlorella sorokiniana and Scenedesmus abundans

The global energy crisis has spurred a shift from conventional to clean and sustainable energy sources. Biomass derived from microalgae is emerging as an alternative energy source with diverse applications. Despite the numerous advantages of microalgae, large-scale biomass harvesting is not economical and convenient. Self-flocculation is considered an effective phenomenon facilitated by extracting the flocculating substances from microalgae that assist aggregation of algal cells into flocs. A novel cellulose-based bioflocculant has been synthesized from sewage water grown Chlorella sorokiniana and Scenedesmus abundans for harvesting application. The produced bioflocculant amounted to 38.5% and 19.38% of the dry weight of S. abundans and C. sorokiniana, respectively. Analysis via FTIR, XRD, and FESEM-EDX revealed the presence of cellulose hydroxyapatite (HA) in algae-derived cellulose. Harvesting efficiencies of 95.3% and 89.16% were attained for S. abundans and C. sorokiniana, respectively, at a dosage of 0.5 g/L. Furthermore, the bioflocculant was recovered, enabling its reuse with recovery efficiencies of 52% and 10% for S. abundans and C. sorokiniana, respectively. This simple and efficient approach has the potential to replace other harvesting methods, thereby contributing to the economic algal biofuel production.

Whole genome sequencing analysis of Komagataeibacter nataicola reveals its potential in food waste valorisation for cellulose production

BACKGROUND

Komagataeibacter nataicola (K. nataicola) is a gram-negative acetic acid bacterium that produces natural bacterial cellulose (BC) as a fermentation product under acidic conditions. The goal of this work was to study the complete genome of K. nataicola and gain insight into the functional genes in K. nataicola that are responsible for BC synthesis in acidic environments.

METHODS AND RESULT

The pure culture of K. nataicola was obtained from yeast-glucose-calcium carbonate (YGC) agar, followed by genomic DNA extraction, and subjected to whole genome sequencing on a Nanopore flongle flow cell. The genome of K. nataicola consists of a 3,767,936 bp chromosome with six contigs and 4,557 protein coding sequences. The maximum likelihood phylogenetic tree and average nucleotide identity analysis confirmed that the bacterial isolate was K. nataicola. The gene annotation via RAST server discovered the presence of cellulose synthase, along with three genes associated with lactate utilization and eight genes involved in lactate fermentation that could potentially contribute to the increase in acid concentration during BC synthesis.

CONCLUSION

A more comprehensive genome study of K. nataicola may shed light into biological pathway in BC productivity as well as benefit the analysis of metabolites generated and understanding of biological and chemical interactions in BC production later.

A review of advanced hydrogels for cartilage tissue engineering

With the increase in weight and age of the population, the consumption of tobacco, inappropriate foods, and the reduction of sports activities in recent years, bone and joint diseases such as osteoarthritis (OA) have become more common in the world. From the past until now, various treatment strategies (e.g., microfracture treatment, Autologous Chondrocyte Implantation (ACI), and Mosaicplasty) have been investigated and studied for the prevention and treatment of this disease. However, these methods face problems such as being invasive, not fully repairing the tissue, and damaging the surrounding tissues. Tissue engineering, including cartilage tissue engineering, is one of the minimally invasive, innovative, and effective methods for the treatment and regeneration of damaged cartilage, which has attracted the attention of scientists in the fields of medicine and biomaterials engineering in the past several years. Hydrogels of different types with diverse properties have become desirable candidates for engineering and treating cartilage tissue. They can cover most of the shortcomings of other treatment methods and cause the least secondary damage to the patient. Besides using hydrogels as an ideal strategy, new drug delivery and treatment methods, such as targeted drug delivery and treatment through mechanical signaling, have been studied as interesting strategies. In this study, we review and discuss various types of hydrogels, biomaterials used for hydrogel manufacturing, cartilage-targeting drug delivery, and mechanosignaling as modern strategies for cartilage treatment.

Glucose metabolism in the pathogenic free-living amoebae: Tempting targets for treatment development

Pathogenic free-living amoebae (pFLA) are single-celled eukaryotes responsible for causing intractable infections with high morbidity and mortality in humans and animals. Current therapeutic approaches include cocktails of antibiotic, antifungal, and antimicrobial compounds. Unfortunately, the efficacy of these can be limited, driving the need for the discovery of new treatments. Pan anti-amebic agents would be ideal; however, identifying these agents has been a challenge, likely due to the limited evolutionary relatedness of the different pFLA. Here, we discuss the potential of targeting amoebae glucose metabolic pathways as the differences between pFLA and humans suggest specific inhibitors could be developed as leads for new therapeutics.

Structure and properties of nitrocellulose: approaching 200 years of research

This review brings together almost 200 years of fragmented research on the structure of nitrocellulose to give an overview that covers production to application in composite materials. As a mouldable plastic, energetic rocket propellant and biomolecular binding membrane, nitrocellulose still finds widespread practical application today despite the inception of synthetic plastics. The influence of different cellulose source materials affects the structure and properties of nitrocellulose in ways that are not fully understood, and so this review brings together relatively recent developments in the understanding of cellulose nanostructures to highlight where the gaps in understanding now reside. The influence of nitration conditions on the material properties of nitrocellulose is described, together with the proposed mechanisms and equilibria associated with these synthetic routes. The reported crystal structures of nitrocellulose are also reviewed, and the confirmed structural features are separated from those yet to be proven. We also consider how nitrocellulose interacts with other compounds, to help explain the distinct properties of its composite materials. This review points to further work that is required to obtain well founded structural models of nitrocellulose, while highlighting opportunities to control and direct its structure to improve its material properties.

Cellulose Synthase in Atacama Cyanobacteria and Bioethanol Production from Their Exopolysaccharides

Cyanobacteria produce exopolysaccharides (EPSs) as an adaptative mechanism against ultraviolet radiation and desiccation. Cellulose is present in the extracellular polymeric substance in some cyanobacteria genera and it has been proposed as a raw material for biofuel production. The goal of this work was to evaluate the cellulose presence in EPS of Atacama cyanobacteria strains and its use as an alternative and innovative biological source to produce bioethanol. The presence of cellulose was evaluated using techniques of molecular biology, bioinformatics, and electronic microscopy. The conserved motif D,D,D,35QXXRW, characteristic of processive β-glycosyltransferase in all cellulose-producing organisms, was identified in the genome of the LLA-10 strain. This is evidence that cellulose synthase in the LLA-10 strain is a functional enzyme. EPS from Atacama cyanobacteria was hydrolyzed by β-glucosidases (cellobiase and cellulase) and the released glucose was yeast-fermented to ethanol. Ethanol production reached 172.69 ± 0.02 mg ethanol/g EPS after 48 h of incubation. These results are the first step in the evaluation of EPS produced by native cyanobacteria isolated from northern Chile for future biotechnological applications such as the production of bioethanol.

Synthesis and Applications of Hybrid Polymer Networks Based on Renewable Natural Macromolecules

Macromolecules obtained from renewable natural sources are gaining increasing attention as components for a vast variety of sustainable polymer-based materials. Natural raw materials can facilitate continuous-flow production due to their year-round availability and short replenishment period. They also open new opportunities for chemists and biologists to design and create "bioreplacement" and "bioadvantaged" polymers, where complex structures produced by nature are being modified, upgraded, and utilized to create novel materials. Bio-based macromonomers are expected not only to compete with but to replace some petroleum-based analogs, as well. The development of novel sustainable materials is an ongoing and very dynamic process. There are multiple strategies for transforming natural macromolecules into sophisticated value-added products. Some methods include chemical modification of macromolecules, while others include blending several components into one new system. One of the most promising approaches for incorporating renewable macromolecules into new products is the synthesis of hybrid networks based on one or more natural components. Each one has unique characteristics, so its incorporation into a network brings new sustainable materials with properties that can be tuned according to their end-use. This article reviews the current state-of-the-art and future potential of renewable natural macromolecules as sustainable building blocks for the synthesis and use of hybrid polymer networks. The most recent advancements and applications that involve polymers, such as cellulose, chitin, alginic acid, gellan gum, lignin, and their derivatives, are discussed.

Perspectives on the Lindman Hypothesis and Cellulose Interactions

In the history of cellulose chemistry, hydrogen bonding has been the predominant explanation when discussing intermolecular interactions between cellulose polymers. This is the general consensus in scholarly textbooks and in many research articles, and it applies to several other biomacromolecules' interactions as well. This rather unbalanced description of cellulose has likely impacted the development of materials based on the processing of cellulose-for example, via dissolution in various solvent systems and regeneration into solid materials, such as films and fibers, and even traditional wood fiber handling and papermaking. In this review, we take as a starting point the questioning of the general description of the nature of cellulose and cellulose interactions initiated by Professor Björn Lindman, based on generic physicochemical reasoning about surfactants and polymers. This dispute, which became known as "the Lindman hypothesis", highlights the importance of hydrophobic interactions in cellulose systems and that cellulose is an amphiphilic polymer. This paper elaborates on Björn Lindman's contribution to the subject, which has caused the scientific community to revisit cellulose and reconsider certain phenomena from other perspectives.

Cellulose: A Review of Water Interactions, Applications in Composites, and Water Treatment

Cellulose is known to interact well with water, but is insoluble in it. Many polysaccharides such as cellulose are known to have significant hydrogen bond networks joining the molecular chains, and yet they are recalcitrant to aqueous solvents. This review charts the interaction of cellulose with water but with emphasis on the formation of both natural and synthetic fiber composites. Covering studies concerning the interaction of water with wood, the biosynthesis of cellulose in the cell wall, to its dispersion in aqueous suspensions and ultimately in water filtration and fiber-based composite materials this review explores water-cellulose interactions and how they can be exploited for synthetic and natural composites. The suggestion that cellulose is amphiphilic is critically reviewed, with relevance to its processing. Building on this, progress made in using various charged and modified forms of nanocellulose to stabilize oil-water emulsions is addressed. The role of water in the aqueous formation of chiral nematic liquid crystals, and subsequently when dried into composite films is covered. The review will also address the use of cellulose as an aid to water filtration as one area where interactions can be used effectively to prosper human life.

Cellulose synthesis in land plants

All plant cells are surrounded by a cell wall that provides cohesion, protection, and a means of directional growth to plants. Cellulose microfibrils contribute the main biomechanical scaffold for most of these walls. The biosynthesis of cellulose, which typically is the most prominent constituent of the cell wall and therefore Earth's most abundant biopolymer, is finely attuned to developmental and environmental cues. Our understanding of the machinery that catalyzes and regulates cellulose biosynthesis has substantially improved due to recent technological advances in, for example, structural biology and microscopy. Here, we provide a comprehensive overview of the structure, function, and regulation of the cellulose synthesis machinery and its regulatory interactors. We aim to highlight important knowledge gaps in the field, and outline emerging approaches that promise a means to close those gaps.

Mutation in the Endo-β-1,4-glucanase (KORRIGAN) Is Responsible for Thick Leaf Phenotype in Sorghum

Sorghum [Sorghum bicolor (L.) Moench] is an important crop for food, feed, and fuel production. Particularly, sorghum is targeted for cellulosic ethanol production. Extraction of cellulose from cell walls is a key process in cellulosic ethanol production, and understanding the components involved in cellulose synthesis is important for both fundamental and applied research. Despite the significance in the biofuel industry, the genes involved in sorghum cell wall biosynthesis, modification, and degradation have not been characterized. In this study, we have identified and characterized three allelic thick leaf mutants (thl1, thl2, and thl3). Bulked Segregant Analysis sequencing (BSAseq) showed that the causal mutation for the thl phenotype is in endo-1,4-β-glucanase gene (SbKOR1). Consistent with the causal gene function, the thl mutants showed decreased crystalline cellulose content in the stem tissues. The SbKOR1 function was characterized using Arabidopsis endo-1,4-β-glucanase gene mutant (rsw2-1). Complementation of Arabidopsis with SbKOR1 (native Arabidopsis promoter and overexpression by 35S promoter) restored the radial swelling phenotype of rsw2-1 mutant, proving that SbKOR1 functions as endo-1,4-β-glucanase. Overall, the present study has identified and characterized sorghum endo-1,4-β-glucanase gene function, laying the foundation for future research on cell wall biosynthesis and engineering of sorghum for biofuel production.

Characteristics of Cellulose Nanofibrils from Transgenic Trees with Reduced Expression of Cellulose Synthase Interacting 1

Cellulose nanofibrils can be derived from the native load-bearing cellulose microfibrils in wood. These microfibrils are synthesized by a cellulose synthase enzyme complex that resides in the plasma membrane of developing wood cells. It was previously shown that transgenic hybrid aspen trees with reduced expression of CSI1 have different wood mechanics and cellulose microfibril properties. We hypothesized that these changes in the native cellulose may affect the quality of the corresponding nanofibrils. To test this hypothesis, wood from wild-type and transgenic trees with reduced expression of CSI1 was subjected to oxidative nanofibril isolation. The transgenic wood-extracted nanofibrils exhibited a significantly lower suspension viscosity and estimated surface area than the wild-type nanofibrils. Furthermore, the nanofibril networks manufactured from the transgenics exhibited high stiffness, as well as reduced water uptake, tensile strength, strain-to-break, and degree of polymerization. Presumably, the difference in wood properties caused by the decreased expression of CSI1 resulted in nanofibrils with distinctive qualities. The observed changes in the physicochemical properties suggest that the differences were caused by changes in the apparent nanofibril aspect ratio and surface accessibility. This study demonstrates the possibility of influencing wood-derived nanofibril quality through the genetic engineering of trees.

The Land-Sea Connection: Insights Into the Plant Lineage from a Green Algal Perspective

The colonization of land by plants generated opportunities for the rise of new heterotrophic life forms, including humankind. A unique event underpinned this massive change to earth ecosystems-the advent of eukaryotic green algae. Today, an abundant marine green algal group, the prasinophytes, alongside prasinodermophytes and nonmarine chlorophyte algae, is facilitating insights into plant developments. Genome-level data allow identification of conserved proteins and protein families with extensive modifications, losses, or gains and expansion patterns that connect to niche specialization and diversification. Here, we contextualize attributes according to Viridiplantae evolutionary relationships, starting with orthologous protein families, and then focusing on key elements with marked differentiation, resulting in patchy distributions across green algae and plants. We place attention on peptidoglycan biosynthesis, important for plastid division and walls; phytochrome photosensors that are master regulators in plants; and carbohydrate-active enzymes, essential to all manner of carbohydratebiotransformations. Together with advances in algal model systems, these areas are ripe for discovering molecular roles and innovations within and across plant and algal lineages.

Polysaccharides and Metal Nanoparticles for Functional Textiles: A Review

Nanotechnology is a powerful tool for engineering functional materials that has the potential to transform textiles into high-performance, value-added products. In recent years, there has been considerable interest in the development of functional textiles using metal nanoparticles (MNPs). The incorporation of MNPs in textiles allows for the obtention of multifunctional properties, such as ultraviolet (UV) protection, self-cleaning, and electrical conductivity, as well as antimicrobial, antistatic, antiwrinkle, and flame retardant properties, without compromising the inherent characteristics of the textile. Environmental sustainability is also one of the main motivations in development and innovation in the textile industry. Thus, the synthesis of MNPs using ecofriendly sources, such as polysaccharides, is of high importance. The main functions of polysaccharides in these processes are the reduction and stabilization of MNPs, as well as the adhesion of MNPs onto fabrics. This review covers the major research attempts to obtain textiles with different functional properties using polysaccharides and MNPs. The main polysaccharides reported include chitosan, alginate, starch, cyclodextrins, and cellulose, with silver, zinc, copper, and titanium being the most explored MNPs. The potential applications of these functionalized textiles are also reported, and they include healthcare (wound dressing, drug release), protection (antimicrobial activity, UV protection, flame retardant), and environmental remediation (catalysts).

Identification of the CesA Subfamily and Functional Analysis of GhMCesA35 in Gossypium Hirsutum L

The cellulose synthase genes control the biosynthesis of cellulose in plants. Nonetheless, the gene family members of CesA have not been identified in the newly assembled genome of Gossypiumhirsutum (AD1, HEBAU_NDM8). We identified 38 CesA genes in G. hirsutum (NDM8) and found that the protein sequence of GhMCesA35 is 100% identical to CelA1 in a previous study. It is already known that CelA1 is involved in cellulose biosynthesis in vitro. However, the function of this gene in vivo has not been validated. In this study, we verified the function of GhMCesA35 in vivo based on overexpressed Arabidopsis thaliana. In addition, we found that it interacted with GhCesA7 through the yeast two-hybrid assay. This study provides new insights for studying the biological functions of CesA genes in G. hirsutum, thereby improving cotton fiber quality and yield.

Enzymatic synthesis of cellulose in space: gravity is a crucial factor for building cellulose II gel structure

ABSTRACT

We previously reported in vitro synthesis of highly ordered crystalline cellulose II by reverse reaction of cellodextrin phosphorylase from the cellulolytic bacterium Clostridium (Hungateiclostridium) thermocellum (CtCDP), but the formation mechanism of the cellulose crystals and highly ordered structure has long been unclear. Considering the specific density of cellulose versus water, the formation of crystalline and highly ordered structure in an aqueous solution should be affected by gravity. Thus, we synthesized cellulose with CtCDP stable variant at the International Space Station, where sedimentation and convection due to gravity are negligible. Optical microscopic observation suggested that cellulose in space has a gel-like appearance without apparent aggregation, in contrast to cellulose synthesized on the ground. Small-angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXS) indicated that cellulose synthesized in space has a more uniform particle distribution in the ~ 100 nm scale region than cellulose synthesized on the ground. Scanning electron microscopy (SEM) showed that both celluloses have a micrometer scale network structure, whereas a fine fiber network was constructed only under microgravity. These results indicate that gravity plays a role in cellulose II crystal sedimentation and the building of network structure, and synthesis in space could play a role in designing unique materials.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s10570-021-04399-0.

Dietary Fiber in Plant Cell Walls—The Healthy Carbohydrates

Dietary fiber (DF) is one of the major classes of nutrients for humans. It is widely distributed in the edible parts of natural plants, with the cell wall being the main DF-containing structure. The DF content varies significantly in different plant species and organs, and the processing procedure can have a dramatic effect on the DF composition of plant-based foods. Given the considerable nutritional value of DF, a deeper understanding of DF in food plants, including its composition and biosynthesis, is fundamental to the establishment of a daily intake reference of DF and is also critical to molecular breeding programs for modifying DF content. In the past decades, plant cell wall biology has seen dramatic progress, and such knowledge is of great potential to be translated into DF-related food science research and may provide future research directions for improving the health benefits of food crops. In this review, to spark interdisciplinary discussions between food science researchers and plant cell wall biologists, we focus on a specific category of DF—cell wall carbohydrates. We first summarize the content and composition of carbohydrate DF in various plant-based foods, and then discuss the structure and biosynthesis mechanism of each carbohydrate DF category, in particular the respective biosynthetic enzymes. Health impacts of DF are highlighted, and finally, future directions of DF research are also briefly outlined.

Surface Modification of Bacterial Cellulose for Biomedical Applications

Bacterial cellulose is a naturally occurring polysaccharide with numerous biomedical applications that range from drug delivery platforms to tissue engineering strategies. BC possesses remarkable biocompatibility, microstructure, and mechanical properties that resemble native human tissues, making it suitable for the replacement of damaged or injured tissues. In this review, we will discuss the structure and mechanical properties of the BC and summarize the techniques used to characterize these properties. We will also discuss the functionalization of BC to yield nanocomposites and the surface modification of BC by plasma and irradiation-based methods to fabricate materials with improved functionalities such as bactericidal capabilities.

Oxidized Product Profiles of AA9 Lytic Polysaccharide Monooxygenases Depend on the Type of Cellulose

Lytic polysaccharide monooxygenases (LPMOs) are essential for enzymatic conversion of lignocellulose-rich biomass in the context of biofuels and platform chemicals production. Considerable insight into the mode of action of LPMOs has been obtained, but research on the cellulose specificity of these enzymes is still limited. Hence, we studied the product profiles of four fungal Auxiliary Activity family 9 (AA9) LPMOs during their oxidative cleavage of three types of cellulose: bacterial cellulose (BC), Avicel PH-101 (AVI), and regenerated amorphous cellulose (RAC). We observed that attachment of a carbohydrate-binding module 1 (CBM1) did not change the substrate specificity of LPMO9B from Myceliophthora thermophila C1 (MtLPMO9B) but stimulated the degradation of all three types of cellulose. A detailed quantification of oxidized ends in both soluble and insoluble fractions, as well as characterization of oxidized cello-oligosaccharide patterns, suggested that MtLPMO9B generates mainly oxidized cellobiose from BC, while producing oxidized cello-oligosaccharides from AVI and RAC ranged more randomly from DP2-8. Comparable product profiles, resulting from BC, AVI, and RAC oxidation, were found for three other AA9 LPMOs. These distinct cleavage profiles highlight cellulose specificity rather than an LPMO-dependent mechanism and may further reflect that the product profiles of AA9 LPMOs are modulated by different cellulose types.

Structural insights into homotrimeric assembly of cellulose synthase CesA7 from Gossypium hirsutum

Cellulose is one of the most abundant organic polymers in nature. It contains multiple β-1,4-glucan chains synthesized by cellulose synthases (CesAs) on the plasma membrane of higher plants. CesA subunits assemble into a pseudo-sixfold symmetric cellulose synthase complex (CSC), known as a 'rosette complex'. The structure of CesA remains enigmatic. Here, we report the cryo-EM structure of the homotrimeric CesA7 from Gossypium hirsutum at 3.5-angstrom resolution. The GhCesA7 homotrimer shows a C3 symmetrical assembly. Each protomer contains seven transmembrane helices (TMs) which form a channel potentially facilitating the release of newly synthesized glucans. The cytoplasmic glycosyltransferase domain (GT domain) of GhCesA7 protrudes from the membrane, and its catalytic pocket is directed towards the TM pore. The homotrimer GhCesA7 is stabilized by the transmembrane helix 7 (TM7) and the plant-conserved region (PCR) domains. It represents the building block of CSCs and facilitates microfibril formation. This structure provides insight into how eukaryotic cellulose synthase assembles and provides a mechanistic basis for the improvement of cotton fibre quality in the future.

Doxorubicin Embedded into Nanofibrillated Bacterial Cellulose (NFBC) Produces a Promising Therapeutic Outcome for Peritoneally Metastatic Gastric Cancer in Mice Models via Intraperitoneal Direct Injection

Natural materials such as bacterial cellulose are gaining interest for their use as drug-delivery vehicles. Herein, the utility of nanofibrillated bacterial cellulose (NFBC), which is produced by culturing a cellulose-producing bacterium (Gluconacetobacter intermedius NEDO-01) in a medium supplemented with carboxymethylcellulose (CMC) that is referred to as CM-NFBC, is described. Recently, we demonstrated that intraperitoneal administration of paclitaxel (PTX)-containing CM-NFBC efficiently suppressed tumor growth in a peritoneally disseminated cancer xenograft model. In this study, to confirm the applicability of NFBC in cancer therapy, a chemotherapeutic agent, doxorubicin (DXR), embedded into CM-NFBC, was examined for its efficiency to treat a peritoneally disseminated gastric cancer via intraperitoneal administration. DXR was efficiently embedded into CM-NFBC (DXR/CM-NFBC). In an in vitro release experiment, 79.5% of DXR was released linearly into the peritoneal wash fluid over a period of 24 h. In the peritoneally disseminated gastric cancer xenograft model, intraperitoneal administration of DXR/CM-NFBC induced superior tumor growth inhibition (TGI = 85.5%) by day 35 post-tumor inoculation, compared to free DXR (TGI = 62.4%). In addition, compared with free DXR, the severe side effects that cause body weight loss were lessened via treatment with DXR/CM-NFBC. These results support the feasibility of CM-NFBC as a drug-delivery vehicle for various anticancer agents. This approach may lead to improved therapeutic outcomes for the treatment of intraperitoneally disseminated cancers.

A review of nanocellulose as a new material towards environmental sustainability

Synthetic polymers, commonly referred to as plastics, are anthropogenic contaminants that adversely affect the natural ecosystems. The continuous disposal of long lifespan plastics has resulted in the accumulation of plastic waste, leading to significant pollution of both marine and terrestrial habitats. Scientific pursuit to seek environment-friendly materials from renewable resources has focused on cellulose, the primary reinforcement component of the cell wall of plants, as it is the most abundantly available biopolymer on earth. This paper provides an overview on the current state of science on nanocellulose research; highlighting its extraction procedures from lignocellulosic biomass. Literature shows that the process used to obtain nanocellulose from lignocellulosic biomass greatly influences its morphology, properties and surface chemistry. The efficacy of chemical methods that use alkali, acid, bleaching agents, ionic liquids, deep eutectic solvent for pre-treatment of biomass is discussed. There has been a continuous endeavour to optimize the pre-treatment protocol as it is specific to lignocellulosic biomass and also depends on factors such as nature of the biomass, process and environmental parameters and economic viability. Nanofibers are primarily isolated through mechanical fibrillation while nanocrystals are predominantly extracted using acid hydrolysis. A concise overview on the ways to improve the yield of nanocellulose from cellulosic biomass is also presented in this review. This work also reviews the techniques used to modify the surface properties of nanocellulose by functionalizing surface hydroxyl groups to impart desirable hydrophilic-hydrophobic balance. An assessment on the emerging application of nanocellulose with an emphasis on development of nanocomposite materials for designing environmentally sustainable products is incorporated. Finally, the status of the industrial production of nanocellulose presented, which indicates that there is a continuously increased demand for cellulose nanomaterials. The demand for cellulose is expected to increase further due to its increasing and broadening applications.

Molecular Dynamics Simulation of Cellulose Synthase Subunit D Octamer with Cellulose Chains from Acetic Acid Bacteria: Insight into Dynamic Behaviors and Thermodynamics on Substrate Recognition

The present study reports the building of a computerized model and molecular dynamics (MD) simulation of cellulose synthase subunit D octamer (CesD) from Komagataeibacter hansenii. CesD was complexed with four cellulose chains having DP = 12 (G12) by model building, which revealed unexpected S-shaped pathways with bending regions. Combined conventional and accelerated MD simulations of CesD complex models were carried out, while the pyranose ring conformations of the glucose residues were restrained to avoid undesirable deviations of the ring conformation from the ⁴C₁ form. The N-terminal regions and parts of the secondary structures of CesD established appreciable contacts with the G12 chains. Hybrid quantum mechanical (QM) and molecular mechanical (MM) simulations of the CesD complex model were performed. Glucose residues located at the pathway bends exhibited reversible changes to the ring conformation into either skewed or boat forms, which might be related to the function of CesD in regulating microfibril production.

Plant-based nanocellulose: A review of routine and recent preparation methods with current progress in its applications as rheology modifier and 3D bioprinting

"Nanocellulose" have captivated the topical sphere of sturdily escalating market for sustainable materials. The review focuses on the comprehensive understanding of the distinct surface chemistry and functionalities pertaining to the renovation of macro-cellulose at nanodimensional scale to provide an intuition of their processing-structure-function prospective. The abundant availability, cost effectiveness and diverse properties associated with plant-based resources have great economical perspective for developing sustainable cellulose nanomaterials. Hence, emphasis has been given on nanocellulose types obtained from plant-based sources. An overarching goal is to provide the recent advancement in the preparation routes of nanocellulose. Considering the excellent shear thinning/thixotropic/gel-like behavior, the review provids an assemblage of publications specifically dealing with its application as rheology modifier with emphasis on its use as bioink for 3D bioprinting for various biomedical applications. Altogether, this review has been oriented in a way to collocate a collective data starting from the historical perspective of cellulose discovery to modern cellulosic chemistry and its renovation as nanocellulose with recent technological hype for broad spanning applications.

Eco-friendly nanocellulose and its biomedical applications: current status and future prospect

Cellulose is the earth's leading natural polymer. It is known for its properties like biocompatibility, high mechanical strength, cost-effectiveness and lightweight. Nanocellulose displays better properties as compared to the native cellulose fibre. The nanocellulose is very remunerative in the arenas of routine application especially in health care, food industry, sanitary products and many more. In the biomedical area, cellulose-based products are utilized in applications like wound healing, dental applications, drug delivery, antimicrobial material, etc. Nanocellulose biomaterials have been commercialised, representing the material of new generation. With the objective to comprehend the contribution of nanocellulose in the current status and future development in biomedical utilisations, the review is focused on cellulose, nanocellulose, types and sources of nanocellulose, its preparation, characteristics, constraints related to its composites through the analysis of certain scientific reports.

The N-terminal zinc finger of CELLULOSE SYNTHASE6 is critical in defining its functional properties by determining the level of homodimerization in Arabidopsis

Primary cell wall cellulose is synthesized by the cellulose synthase complex (CSC) containing CELLULOSE SYNTHASE1 (CESA1), CESA3 and one of four CESA6-like proteins in Arabidopsis. It has been proposed that the CESA6-like proteins occupy the same position in the CSC, but their underlying selection mechanism remains unclear. We produced a chimeric CESA5 by replacing its N-terminal zinc finger with its CESA6 counterpart to investigate the consequences for its homodimerization, a crucial step in forming higher-order structures during assembly of the CSC. We found that the mutant phenotypes of prc1-1, a cesa6 null mutant, were rescued by the chimeric CESA5, and became comparable to the wild type (WT) and prc1-1 complemented by WT CESA6 in regard to plant growth, cellulose content, cellulose microfibril organization, CSC dynamics and subcellular localization. Bimolecular fluorescence complementation assays were employed to evaluate pairwise interactions between the N-terminal regions of CESA1, CESA3, CESA5, CESA6 and the chimeric CESA5. We verified that the chimeric CESA5 explicitly interacted with all the other CESA partners, comparable to CESA6, whereas interaction between CESA5 with itself was significantly weaker than that of all other CESA pairs. Our findings suggest that the homodimerization of CESA6 through its N-terminal zinc finger is critical in defining its functional properties, and possibly determines its intrinsic roles in facilitating higher-order structures in CSCs.

Prime Editing Technology and Its Prospects for Future Applications in Plant Biology Research

Many applications in plant biology requires editing genomes accurately including correcting point mutations, incorporation of single-nucleotide polymorphisms (SNPs), and introduction of multinucleotide insertion/deletions (indels) into a predetermined position in the genome. These types of modifications are possible using existing genome-editing technologies such as the CRISPR-Cas systems, which require induction of double-stranded breaks in the target DNA site and the supply of a donor DNA molecule that contains the desired edit sequence. However, low frequency of homologous recombination in plants and difficulty of delivering the donor DNA molecules make this process extremely inefficient. Another kind of technology known as base editing can perform precise editing; however, only certain types of modifications can be obtained, e.g., C/G-to-T/A and A/T-to-G/C. Recently, a new type of genome-editing technology, referred to as "prime editing," has been developed, which can achieve various types of editing such as any base-to-base conversion, including both transitions (C→T, G→A, A→G, and T→C) and transversion mutations (C→A, C→G, G→C, G→T, A→C, A→T, T→A, and T→G), as well as small indels without the requirement for inducing double-stranded break in the DNA. Because prime editing has wide flexibility to achieve different types of edits in the genome, it holds a great potential for developing superior crops for various purposes, such as increasing yield, providing resistance to various abiotic and biotic stresses, and improving quality of plant product. In this review, we describe the prime editing technology and discuss its limitations and potential applications in plant biology research.

Cellulose-rich secondary walls in wave-swept red macroalgae fortify flexible tissues

Cellulosic secondary walls evolved convergently in coralline red macroalgae, reinforcing tissues against wave-induced breakage, despite differences in cellulose abundance, microfibril orientation, and wall structure. Cellulose-enriched secondary cell walls are the hallmark of woody vascular plants, which develop thickened walls to support upright growth and resist toppling in terrestrial environments. Here we investigate the striking presence and convergent evolution of cellulosic secondary walls in coralline red algae, which reinforce thalli against forces applied by crashing waves. Despite ostensible similarities to secondary wall synthesis in land plants, we note several structural and mechanical differences. In coralline red algae, secondary walls contain three-times more cellulose (~ 22% w/w) than primary walls (~ 8% w/w), and their presence nearly doubles the total thickness of cell walls (~ 1.2 µm thick). Field emission scanning electron microscopy revealed that cellulose bundles are cylindrical and lack any predominant orientation in both primary and secondary walls. His-tagged recombinant carbohydrate-binding module differentiated crystalline and amorphous cellulose in planta, noting elevated levels of crystalline cellulose in secondary walls. With the addition of secondary cell walls, Calliarthron genicular tissues become significantly stronger and tougher, yet remain remarkably extensible, more than doubling in length before breaking under tension. Thus, the development of secondary walls contributes to the strong-yet-flexible genicular tissues that enable coralline red algae to survive along wave-battered coastlines throughout the NE Pacific. This study provides an important evolutionary perspective on the development and biomechanical significance of secondary cell walls in a non-model, non-vascular plant.

A mutation in the catalytic domain of cellulose synthase 6 halts its transport to the Golgi apparatus

Cellulose microfibrils, which form the mechanical framework of the plant cell wall, are synthesized by the cellulose synthase complex in the plasma membrane. Here, we introduced point mutations into the catalytic domain of cellulose synthase 6 (CESA6) in Arabidopsis to produce enhanced yellow fluorescent protein (EYFP)-tagged CESA6D395N, CESA6Q823E, and CESA6D395N+Q823E, which were exogenously produced in a cesa6 null mutant, prc1-1. Comparison of these mutants in terms of plant phenotype, cellulose content, cellulose synthase complex dynamics, and organization of cellulose microfibrils showed that prc1-1 expressing EYFP:CESA6D395N or CESA6D395N+Q823E was nearly the same as prc1-1, whereas prc1-1 expressing EYFP:CESA6Q823E was almost identical to wild type and prc1-1 expressing EYFP:WT CESA6, indicating that CESA6D395N and CESA6D395N+Q823E do not function in cellulose synthesis, while CESA6Q823E is still functionally active. Total internal reflection fluorescence microscopy and confocal microscopy were used to monitor the subcellular localization of these proteins. We found that EYFP:CESA6D395N and EYFP:CESA6D395N+Q823E were absent from subcellular regions containing the Golgi and the plasma membrane, and they appeared to be retained in the endoplasmic reticulum. By contrast, EYFP:CESA6Q823E had a normal localization pattern, like that of wild-type EYFP:CESA6. Our results demonstrate that the D395N mutation in CESA6 interrupts its normal transport to the Golgi and its eventual participation in cellulose synthase complex assembly.

Natural Polysaccharide Nanomaterials: An Overview of Their Immunological Properties

Natural occurring polymers, or biopolymers, represent a huge part of our planet biomass. They are formed by long chains of monomers of the same type or a combination of different ones. Polysaccharides are biopolymers characterized by complex secondary structures performing several roles in plants, animals, and microorganisms. Because of their versatility and biodegradability, some of them are extensively used for packaging, food, pharmaceutical, and biomedical industries as sustainable and renewable materials. In the recent years, their manipulation at the nanometric scale enormously increased the range of potential applications, boosting an interdisciplinary research attempt to exploit all the potential advantages of nanostructured polysaccharides. Biomedical investigation mainly focused on nano-objects aimed at drug delivery, tissue repair, and vaccine adjuvants. The achievement of all these applications requires the deep knowledge of polysaccharide nanomaterials' interactions with the immune system, which orchestrates the biological response to any foreign substance entering the body. In the present manuscript we focused on natural polysaccharides of high commercial importance, namely, starch, cellulose, chitin, and its deacetylated form chitosan, as well as the seaweed-derived carrageenan and alginate. We reviewed the available information on their biocompatibility, highlighting the importance of their physicochemical feature at the nanoscale for the modulation of the immune system.

Latest Advances on Bacterial Cellulose-Based Materials for Wound Healing, Delivery Systems, and Tissue Engineering

Bacterial cellulose (BC) is a nanocellulose form produced by some nonpathogenic bacteria. BC presents unique physical, chemical, and biological properties that make it a very versatile material and has found application in several fields, namely in food industry, cosmetics, and biomedicine. This review overviews the latest state-of-the-art usage of BC on three important areas of the biomedical field, namely delivery systems, wound dressing and healing materials, and tissue engineering for regenerative medicine. BC will be reviewed as a promising biopolymer for the design and development of innovative materials for the mentioned applications. Overall, BC is shown to be an effective and versatile carrier for delivery systems, a safe and multicustomizable patch or graft for wound dressing and healing applications, and a material that can be further tuned to better adjust for each tissue engineering application, by using different methods.

Missense mutations in a transmembrane domain of the Komagataeibacter xylinus BcsA lead to changes in cellulose synthesis

BACKGROUND

Cellulose is synthesized by an array of bacterial species. Komagataeibacter xylinus is the best characterized as it produces copious amounts of the polymer extracellularly. Despite many advances in the past decade, the mechanisms underlying cellulose biosynthesis are not completely understood. Elucidation of these mechanisms is essential for efficient cellulose production in industrial applications.

RESULTS

In an effort to gain a better understanding of cellulose biosynthesis and its regulation, cellulose crystallization was investigated in K. xylinus mutants resistant to an inhibitor of cellulose I formation, pellicin. Through the use of forward genetics and site-directed mutagenesis, A449T and A449V mutations in the K. xylinus BcsA protein were found to be important for conferring high levels of pellicin resistance. Phenotypic analysis of the bcsA^A449T and bcsA^A449V cultures revealed that the mutations affect cellulose synthesis rates and that cellulose crystallinity is affected in wet pellicles but not dry ones.

CONCLUSIONS

A449 is located in a predicted transmembrane domain of the BcsA protein suggesting that the structure of the transmembrane domain influences cellulose crystallization either by affecting the translocation of the nascent glucan chain or by allosterically altering protein-protein interactions.

Genome-Wide Identification, Expression Pattern Analysis and Evolution of the Ces/Csl Gene Superfamily in Pineapple (Ananas comosus)

The cellulose synthase (Ces) and cellulose synthase-like (Csl) gene families belonging to the cellulose synthase gene superfamily, are responsible for the biosynthesis of cellulose and hemicellulose of the plant cell wall, and play critical roles in plant development, growth and evolution. However, the Ces/Csl gene family remains to be characterized in pineapple, a highly valued and delicious tropical fruit. Here, we carried out genome-wide study and identified a total of seven Ces genes and 25 Csl genes in pineapple. Genomic features and phylogeny analysis of Ces/Csl genes were carried out, including phylogenetic tree, chromosomal locations, gene structures, and conserved motifs identification. In addition, we identified 32 pineapple AcoCes/Csl genes with 31 Arabidopsis AtCes/Csl genes as orthologs by the syntenic and phylogenetic approaches. Furthermore, a RNA-seq investigation exhibited the expression profile of several AcoCes/Csl genes in various tissues and multiple developmental stages. Collectively, we provided comprehensive information of the evolution and function of pineapple Ces/Csl gene superfamily, which would be useful for screening out and characterization of the putative genes responsible for tissue development in pineapple. The present study laid the foundation for future functional characterization of Ces/Csl genes in pineapple.

Multifunctional nanocellulose/metal and metal oxide nanoparticle hybrid nanomaterials

Nanocellulose materials are derived from cellulose, the most abundant biopolymer on the earth. Nanocellulose have been extensively used in the field of food packaging materials, wastewater treatment, drug delivery, tissue engineering, hydrogels, aerogels, sensors, pharmaceuticals, and electronic sectors due to their unique chemical structure and excellent mechanical properties. On the other hand, metal and metal oxide nanoparticles (NP) such as Ag NP, ZnO NP, CuO NP, and Fe₃O₄ NP have a variety of functional properties such as UV-barrier, antimicrobial, and magnetic properties. Recently, nanocelluloses materials have been used as a green template for producing metal or metal oxide nanoparticles. As a result, multifunctional nanocellulose/metal or metal oxide hybrid nanomaterials with high antibacterial properties, ultraviolet barrier properties, and mechanical properties were prepared. This review emphasized recent information on the synthesis, properties, and potential applications of multifunctional nanocellulose-based hybrid nanomaterials with metal or metal oxides such as Ag NP, ZnO NP, CuO NP, and Fe₃O₄ NP. The nanocellulose-based hybrid nanomaterials have huge potential applications in the area of food packaging, biopharmaceuticals, biomedical, and cosmetics.

Knockdown of Dinoflagellate Cellulose Synthase CesA1 Resulted in Malformed Intracellular Cellulosic Thecal Plates and Severely Impeded Cyst-to-Swarmer Transition

Cellulose synthesis (CS) is conducted by membrane-bound cellulose synthase complexes (CSCs), containing cellulose synthases (CesA), that are either arranged in hexagonal structures in higher plants or in linear arrays in most microbial organisms, including dinoflagellates. Dinoflagellates are a major phytoplankton group having linear-type CSCs and internal cellulosic thecal plates (CTPs) in large cortical vesicles. Immunological study suggested CesA1p were cortically localized to the periphery of CTPs. During cyst-to-swarmer transition (T_C–S), synchronized peaks of CesA1 transcription, CesA1p expression, CS and CTP formation occurred in respective order, over 12–16 h, strategically allowing the study of CS regulation and CTP biogenesis. CesA1-knockdown resulted in 40% reduction in CesA1p level and time required for swarmer cells reappearance. CTPs were severely malformed with reduced cellulose content. As CTPs are deposited in internal organelle, the present study demonstrated dinoflagellate CesA1 ortholog was adapted for non-surface deposition; this is different to paradigm of other CesAps which require plasmamembrane for cellulose fiber deposition. This pioneer gene-knockdown study demonstrated the requirement of a gene for dinoflagellate cell wall remodeling and proper T_C–S, which are prominent in dinoflagellate life-cycles.