Simultaneous enzymatic saccharification and comminution for the valorization of lignocellulosic biomass toward natural products.

BACKGROUND: Large-scale processing of lignocellulosics for glucose production generally relies on high temperature and acidic or alkaline conditions. However, extreme conditions produce chemical contaminants that complicate downstream processing. A method that mainly rely on mechanical and enzymatic reaction completely averts such problem and generates unmodified lignin. Products from this process could find novel applications in the chemicals, feed and food industry. But a large-scale system suitable for this purpose is yet to be developed. In this study we applied simultaneous enzymatic saccharification and communition (SESC) for the pre-treatment of a representative lignocellulosic biomass, cedar softwood, under both laboratory and large-scale conditions. RESULTS: Laboratory-scale comminution achieved a maximum saccharification efficiency of 80% at the optimum pH of 6. It was possible to recycle the supernatant to concentrate the glucose without affecting the efficiency. During the direct alcohol fermentation of SESC slurry, a high yield of ethanol was attained. The mild reaction conditions prevented the generation of undesired chemical inhibitors. Large-scale SESC treatment using a commercial beads mill system achieved a saccharification efficiency of 60% at an energy consumption of 50 MJ/kg biomass. CONCLUSION: SESC is very promising for the mild and clean processing of lignocellulose to generate glucose and unmodified lignin in a large scale. Economic feasibility is highly dependent on its potential to generate high value natural products for energy, specialty chemicals, feed and food application.

Tuneable shape-memory properties of composites based on nanoparticulated plant biomass, lignin, and poly(ethylene carbonate).

In this article, we propose a thermally responsive shape-memory polymer (SMP) consisting of poly(ethylene carbonate) and non-deteriorated lignin nanoparticles. This SMP was obtained readily by thermal kneading and melt molding without requiring any chemical reaction. The shape-recovering properties of the SMP can be tuned by changing the feed ratio of the components. The estimation of viscoelastic, thermal and mechanical properties of the SMP reveals that the stepwise structural transitions in the SMP rendered a dynamic shape-recovering behavior.

Chiral-Linkage-Induced Hierarchical Ordering of Colloidal Achiral Nanotubes in their Thixotropic Gel.

Macroscopic continuous hierarchical ordering of achiral nanotube "imogolite" was achieved by thixotropic gelation of imogolite with chiral hydroxy acid and their flow-orienting/subsequent standing for uniaxial alignments of imogolite. The chirality change of the hydroxy acids resulted in an inversion of the helical ordering. The study presented here first exhibits the millimeter-scale supramolecular chirality induced by angstrom-scale molecular handedness in the architecture of nanotubes.

Helical alignment inversion of microtubules in accordance with a structural change in their lattice.

Giant helical (oriented chiral nematic) alignments of microtubules of nanometer to centimeter lengths are known to form over a temperature gradient during anisotropic spiral propagation via tubulin dimer addition in a capillary cell. Such helical alignments may be modified by the addition of either paclitaxel or dimethyl sulfoxide, which induces a lattice (helical) structural change in the microtubule itself. In this study, we found that the lattice structural change of microtubules brings about inversion of microtubule alignments in the helical ordering. Based on microscopy and scattering data, a mechanism for the helical ordering of microtubules is discussed in relation to their lattice (helical) structure.

Direct evidence for structural transition promoting shear thinning in cylindrical colloid assemblies.

In this paper, we describe stimuli-responsive hydrogels prepared from a rigid rod-like polyelectrolyte 'imogolite' and a dicarboxylic acid. The hydrogel exhibited thixotropy in response to mechanical shock within the order of seconds or sub-seconds. Here, using the latest structural/rheological characterisation techniques, the relationship between the structural transition processes and the shear thinning was estimated. The evidence obtained by the experiments revealed for the first time the direct relationship between the microscopic structural change and the macroscopic thixotropic behavior that have been extensively discussed. The thixotropic hydrogel has the hierarchical architecture in the combination of imogolite and dicarboxylic acid, i.e., sheathed nanotubes/hydroclusters of cross-bridged nanotubes/frameworks. The formation and disintegration of the network structure upon resting and agitating, respectively, were the origin of gel/sol transition (thixotropy), although the hydroclusters of cross-bridged nanotubes were maintained throughout the transition.

Preparation of a sulfo-group-containing rod-like polysilsesquioxane with a hexagonally stacked structure and its proton conductivity.

A sulfo-group-containing rod-like polysilsesquioxane with a hexagonally stacked structure (PSQ-SO3H) was successfully prepared by oxidation and hydrolytic polycondensation of 3-mercaptopropyltrimethoxysilane (MPTMS) in a mixed aqueous solution of NaOH and H2O2. The X-ray diffraction pattern of the PSQ-SO3H film exhibited three diffraction peaks with a d-value ratio of 1:1/√3:1/2, indicating the formation of a hexagonally stacked structure. In addition, the transmission electron microscopy image of PSQ-SO3H exhibited a striped pattern, indicating that the rod-like PSQs were stacked in a parallel fashion. The presence of ionic side-chains composed of the sulfonate anions and sodium cations during the hydrolytic polycondensation of MPTMS was found to be essential for the formation of this regularly structured PSQ. Finally, the proton conductivity of the PSQ-SO3H film, determined by using complex impedance spectroscopy, was relatively high (>10(-2) S cm(-1)) at 80 °C and 30-90 % relative humidity.

Thermoresponsive synthetic polymer-microtubule hybrids.

Thermoresponsive hybrids consisting of synthetic polymers and microtubules (MTs), i.e., assemblies of tubulins, were prepared by bonding MTs covalently to a few reactive units in a macromolecular strand. The hybrids exhibited the gel/sol transition because of the "assembling of tubulins to MTs/disintegrating of MTs to tubulins" by the temperature change between 37 and 4 °C, respectively. The viscoelastic behaviors of the hybrid gels depended upon the quantity of polymer feed and the amount of resulting covalent bonds between the polymers and tubulin units. Furthermore, in a confined space of a thin and long rectangular cell with the temperature gradient from 4 °C (cold terminal) to 37 °C (warm terminal), the sol state hybrid turned to the gel state that propagated from the warm terminal toward the cold terminal to form uniaxially oriented MT arrays. Upon changing the temperature of the whole system between 37 and 4 °C, the uniaxial arrays appeared/disappeared reversibly.

Spontaneous Alignment of Microtubules Via Tubulin Polymerization in a Narrow Space Under a Temperature Gradient.

In this chapter, protocols for spontaneous alignment of microtubules (MTs), such as helices and spherulites, via tubulin polymerization in a narrow space and under a temperature gradient are presented for tubulin solutions and tubulin-polymer mixtures. These protocols provide an easy route for hierarchical MT assembly and may extend our current understanding of cytoskeletal protein self-assembly under dissipative conditions.

Correction: Enhanced ionic conduction in composite polymer electrolytes filled with plant biomass "lignin".

Correction for 'Enhanced ionic conduction in composite polymer electrolytes filled with plant biomass "lignin"' by Zitong Liu et al., Chem. Commun., 2022, DOI: 10.1039/d1cc07148c.

Enhanced ionic conduction in composite polymer electrolytes filled with plant biomass "lignin".

The addition of a small amount of plant biomass-based lignin causes a large improvement in the ionic conductivity of composite polymer electrolytes at room temperature, which can be fabricated easily in a low carbon way for use in future all-solid-state battery applications.

Electrically conducting films prepared from graphite and lignin in pure water.

In this study, we present electrically conducting self-standing graphite films consisting of lignin derivatives extracted by simultaneous enzymatic saccharification and comminution (SESC). Sonication of graphite powder in the presence of SESC lignin and pure water allows dispersion of the SESC-lignin-attached graphite without addition of other chemicals. The SESC-lignin-attached graphite having a diameter of several micrometers can be used as a surface electroconductive coating and molded into self-standing films by drying. The SESC-lignin-attached graphite film exhibits higher conductivity (∼2,075 S/cm) than graphite-based composites consisting of ordinary lignin derivatives. Manufacturing self-standing films of micrometer-sized graphite using SESC lignin enables high electrical conductivity of the SESC-lignin-attached graphite film. The size of the SESC-lignin-attached graphite is proportional to the conductivity of the film. The SESC-lignin-attached graphite also acts as an antiplasticizer and a conductive filler for polymer films, i.e., conductive films consisting of poly(ethylene glycol) or Li+ montmorillonite can be obtained through a water-based process.

Controlled clockwise-counterclockwise motion of the ring-shaped microtubules assembly.

The microtubule (MT)-kinesin system has been proposed as the building block of biomolecular motor based artificial biomachines. Considerable efforts have been devoted to integrate this system that produced a variety of ordered structures including the ring-shaped MT assembly which is being considered as a promising candidate for the further development of the biomachines. However, lack of proper knowledge that might help tune the direction of motion of ring-shaped microtubule assembly from counterclockwise to clockwise direction, and vice versa, significantly restricted their potential applications. We report our success in controlling the direction of rotational motion of ring-shaped MT assembly by altering the preparation conditions of microtubules. The change in the direction of rotation of MT rings could be interpreted in terms of the accompanied structural rearrangement of the MT lattice. For achieving handedness-regulated efficient biomachines having tunable asymmetric property, our study will be significantly directive.

Nonflammable UV protective films consisting of clay and lignin with tunable light/gas transparency.

In this paper, we present nonflammable UV protective films consisting of clay minerals and lignin derivatives. The nonflammable transparent films were produced by mixing clay with a lignin derivative extracted from plants by simultaneous enzymatic saccharification and comminution. The preparation procedure did not require hazardous chemicals. The optical properties and gas permeability of the films could be tuned by the components and phase separation structure of the clay minerals and lignin derivatives. In particular, the gas transmittance of the films could be controlled in the range of several mol m-2 s-1 Pa-1. The present film uses mineral and plant components as high-value industrial materials and reduces the environmental load of extracting limited petroleum-based resources.

Flexible, transparent nanocomposite film with a large clay component and ordered structure obtained by a simple solution-casting method.

A flexible, transparent nanocomposite (NC) film with 57 wt % inorganic components was obtained by the simple casting of a solution of Laponite and modified organic molecules through a sol-gel reaction. The NC film has solvent resistance and a disco-nematic liquid-crystalline-like structure of Laponite that originates from the cross linking of Laponite by silanol agents and the large amount of Laponite in the film.

Radial alignment of microtubules through tubulin polymerization in an evaporating droplet.

We report the formation of spherulites from droplets of highly concentrated tubulin solution via nucleation and subsequent polymerization to microtubules (MTs) under water evaporation by heating. Radial alignment of MTs in the spherulites was confirmed by the optical properties of the spherulites observed using polarized optical microscopy and fluorescence microscopy. Temperature and concentration of tubulins were found as important parameters to control the spherulite pattern formation of MTs where evaporation plays a significant role. The alignment of MTs was regulated reversibly by temperature induced polymerization and depolymerization of tubulins. The formation of the MTs patterns was also confirmed at the molecular level from the small angle X-ray measurements. This work provides a simple method for obtaining radially aligned arrays of MTs.

Formation of well-oriented microtubules with preferential polarity in a confined space under a temperature gradient.

Tubulin polymerization in a confined space under a temperature gradient produced well-oriented microtubule assemblies with preferential polarity. We analyzed the structure and polarity of these assemblies at various levels of resolution by performing polarized light microscopy (millimeter order), fluorescence microscopy (micrometer order), and transmission electron microscopy (nanometer order).

Solvent-Free Fabrication of an Elastomeric Epoxy Resin Using Glycol Lignin from Japanese Cedar.

In this study, a simple formulation of softwood-derived glycol lignin (GL)-based epoxy resin with a high GL content of greater than 50 wt % was demonstrated by direct mixing with poly(ethylene glycol) diglycidyl ether (PEGDGE), an aliphatic epoxide, without using any solvent. Because the GL powder produced from poly(ethylene glycol) (PEG400) solvolysis of Japanese cedar softwood meal was a PEG400-modified lignin (GL400), a strong affinity between PEG counterparts facilitates the uniform mixing of GL400 with PEGDGE, and one component uncured GL400/PEGDGE epoxy resin was prepared at a relatively lower temperature (100 °C) than the curing temperature (130 °C). The epoxy curing reaction was monitored by 1H NMR and Fourier transform infrared spectroscopies. The physical and mechanical properties of the epoxy resins with different GL400 contents were then evaluated. The developed resins exhibited good flexibility and elasticity depending on the GL400 content.

Ring-shaped assembly of microtubules shows preferential counterclockwise motion.

In this paper, we reveal that microtubules (MTs), reconstructed from tubulin in vitro in the presence of guanosine-5'-triphosphate (GTP), have a ring or spiral shape on a motor protein-fixed surface, and these MTs show biased motion in the counterclockwise direction. By cross-linking these MTs during the sliding motion, we obtained large ring-shaped MT assemblies, 1 approximately 12.6 microm in diameter. The ratio of the rings rotating in the counterclockwise direction to those rotating in the clockwise direction was approximately 3/1. Under optimized conditions, the ratio was as high as 14/1. Thus, we successfully obtained aggregated MTs with a large hierarchic structure that shows a preferential motion, through a dynamic process in vitro.

Observation of the three-dimensional structure of actin bundles formed with polycations.

Three-dimensional structures of actin bundles formed with polycations were observed by using transmission electron microtomography and atomic force microscopy. We found, for the first time, that the cross-sectional morphology of actin bundles depends on the polycation species and ionic strength, while it is insensitive to the degree of polymerization and concentration of polycation. Actin bundles formed with poly-N-[3-(dimethylamino)propyl] acrylamide methyl chloride quaternary show a ribbon-like cross-sectional morphology in low salt concentrations that changes to cylindrical cross-sectional morphology with hexagonal packing of the actin filaments in high salt concentrations. Contrastingly, actin bundles formed with poly-L-lysine show triangular cross-sectional morphology with hexagonal packing of the actin filaments. These variations in cross-sectional morphology are discussed in terms of anisotropy in the electrostatic energy barrier.

Integration of motor proteins - towards an ATP fueled soft actuator.

We present a soft bio-machine constructed from biological motors (actin/myosin). We have found that chemically cross-linked polymer-actin complex gel filaments can move on myosin coated surfaces with a velocity as high as that of native F-actin, by coupling to ATP hydrolysis. Additionally, it is shown that the velocity of polymer-actin complex gel depends on the species of polycations binding to the F-actins. Since the design of functional actuators of well-defined size and morphology is important, the structural behavior of polymer-actin complexes has been investigated. Our results show that the morphology and growth size of polymer-actin complex can be controlled by changes in the electrostatic interactions between F-actins and polycations. Our results indicate that bio actuators with desired shapes can be created by using a polymer-actin complex.