2020 Activity Report for Mission 5-2: Establishing a Society with Reduced Dependence on Fossil Resources: Plants, Biomass, Energy, and Materials

Updated: 2021/04/30

Research 1: Tailor-made breeding of grass biomass through lignin bioengineering

RISH investigator(s): Toshiaki Umezawa, Yuki Tobimatsu
Outside collaborator(s): Tokushima University, Nara Institute of Science and Technology (NAIST), Hokkaido University, Korea University, The University of Hong Kong, University of Wisconsin, Oklahoma University, CAS Shanghai Institute of Plant Physiology and Ecology, etc

To explore new breeding strategies to improve the production of bioenergy and biomaterials from grass biomass, this project seeks to develop and characterize transgenic rice plants that produce biomass with variously modified lignin contents and structures. To this end, new lignin-modified transgenic rice lines are being developed via up- and/or down-regulations of lignin biosynthesis pathway genes. We are also working on the selection and breeding of grass biomass crop varieties that show superior lignin characteristics.

Figure: Lignin-modified transgenic rice plants grown in a greenhouse (left) and structural models of lignins in grass biomass or cell walls (right).

Selected Publications

  1. Miyamoto et al., MYB-mediated regulation of lignin biosynthesis in grasses. Plant Biol., 24: 100174 (2020).
  2. Umezawa et al., Lignin metabolic engineering in grasses for primary lignin valorization. Lignin, 1: 30-41 (2020).
  3. Lui et al., Convergent recruitment of 5´‐hydroxylase activities by CYP75B flavonoid B‐ring hydroxylases for tricin biosynthesis in Medicago legumes. New Phytol., 228, 269-284 (2020).
  4. Kim et al., The Arabidopsis R2R3 MYB transcription factor MYB15 is a key regulator of lignin biosynthesis in effector-triggered immunity. Plant Biol., 11: 583153 (2020).
  5. Hori et al. Identifying transcription factors that reduce wood recalcitrance and improve enzymatic degradation of xylem cell wall in Populus. Rep. 10: 22043 (2020).

Research 2: Metabolite production platform using lipid-secreting plant cells

RISH investigator(s): Kazufumi Yazaki, Akifumi Sugiyama, Ryosuke Munakata
Outside collaborator(s): RIKEN 

Plants have developed lipid secretion mechanisms to protect themselves from dryness since the land colonization of plants in ancient agesThe lipid secretion ability is especially prominent in epidermal cells, where wax and cutins as well as suberin are secreted. Besides, some other characteristic cell types related to oil glands and glandular trichomes are also responsible for secretion of lipid-soluble low molecular weight substances, like secondary metabolites. One of such examples is Lithospermum erhthrorhizon, in which root epidermal cells are secreting a large amount of secondary metabolic lipids, i.e., shikonin derivatives. The cultured cells of this plant retain the shikonin productivity of ca. 10% per cell dry weight. In this study, we are trying to develop a production system of high value lipid-soluble metabolites utilizing the lipid secreting ability of this cultured plant cells as a platform.

Figure: Metabolite production platform using lipid-secreting plant cells

Selected Publications

  1. Yamamoto et al., Alcohol dehydrogenase activity converts 3″-hydroxygeranylhydro-quinone to an aldehyde intermediate for shikonin and benzoquinone derivatives in Lithospermum erythrorhizon, Plant Cell Physiol., 61: 1798-1806 (2020).
  2. Ueoka et al., A cytosol-localized geranyl diphosphate synthase from Lithospermum erythrorhizon and its molecular evolution, Plant Physiol., 182: 1933-1945 (2020).
  3. Izuishi et al., Apple latent spherical virus (ALSV)-induced gene silencing in a medicinal plant, Lithospermum erythrorhizon, Rep., 10: 13555 (2020).
  4. Oshikiri et al., Two BAHD acyltransferases catalyze the last step in the shikonin/alkannin biosynthetic pathway, Plant Physiol., 184; 753-761 (2020).
  5. Tatsumi, K., et al., Highly efficient method of Lithospermum erythrorhizon transformation using domestic Rhizobium rhizogenes strain A13, Plant Biotech., 37 (1), 39-46 (2020).

Research 3: Conversion of biomass into chemical resources using a microwave and biological process

RISH investigator(s): Takashi Watanabe, Hiroshi Nishimura
Outside collaborator(s): Kyoto University ICR, Kyoto University IAE, Nippon Steel Engineering Co., Daicel Corporation, Thailand National Science and Technology Development Agency (NSTDA), Indonesian Institute of Science (LIPI), National University of Laos (NUOL), Al-Azhar University、etc.

We are studying conversion system of tropical and domestic biomass into functional chemicals and biofuels. We are conducting an e-Asia program “Integrated Biorefinery of Sugarcane Trash”. The program is leaded by RISH, together with Graduate School of Energy Science of Kyoto University (KU), Institute of Advanced Energy of KU, National Science and Technology Development Agency (NSTDA) in Thailand, Indonesian Institute of Sciences (LIPI) and National University of Laos (NUOL). We are studying conversion system of sugarcane trash to advanced biofuels, useful chemicals and materials such as iso-butanol, ethanol, xylitol and lignin-derived surfactant, thereby contributing to the sustainable development of local societies. In FY2020, we also studied wood solubilization in organic acid together with a private company.

Figure: e-Asia project ”Integrated biorefinery of sugarcane trash”

Selected Publications

  1. Bunterngsook et al., Identification and characterization of a novel AA9-type lytic polysaccharide monooxygenase from a bagasse metagenome. Microbiol. Biotechnol. 105: 197–210 (2021).
  2. Alam et al. Biodegradation and metabolic pathway of anthraquinone dyes by Trametes hirsuta D7 immobilized in light expanded clay aggregate and cytotoxicity assessment. Hazard. Mater. in press (2021).
  3. Tokunaga et al. NMR elucidation of nonproductive binding sites of lignin models with carbohydrate-binding module of cellobiohydrolase I. Biofuels, 13: 164 (2020).
  4. Tokunaga et al. Complete NMR assignment and analysis of molecular structural changes of β-O-4 lignin oligomer model compounds in organic media with different water content. Holzforshung, in press (2021).
  5. Qu et al., Directly microwave‐accelerated cleavage of C−C and C−O bonds of lignin by copper oxide and H2O2, ChemSusChem, 13: 4510-4518 (2020).


Research 4: Design of green biomass conversion based on an analysis of branched structures on lignocellulose

RISH investigator(s): Hiroshi Nishimura, Takashi Watanabe
Outside collaborator(s): Chalmers University of Technology, Wallenberg Wood Science Center (WWSC), Kyoto University ICR, etc.

Advanced utilization of plant biomass needs a deeper understanding of the molecular structure of lignocellulose polymers. In particular, branched structures on lignocellulose, e.g., lignin-polysaccharide linkages, are critical to elucidate for converting biomass to useful chemicals, materials, and energy. Here, we established a highly concentrated fraction of lignin-carbohydrate complexes and purified by combining of carbohydrase enzymatic treatment and sequential chromatography.  We succeeded in proving the covalent bond between lignin and hemicellulose by two-dimensional and three-dimensional NMR method. We are now trying to develop the environment-friendly green system of biomass conversion based on the accurate molecular structure analysis.

Figure: Study overview of the lignin-carbohydrate linkage elucidation


Selected Publications

  1. Tsubaki et al., Probing rapid carbon fixation in fast-growing seaweed Ulva meridionalis using stable isotope 13C-labelling, Sci. Rep., 10:1 (2020).
  2. Chotirotsukon et al., Sequential fractionation of sugarcane bagasse using liquid hot water and formic acid-catalyzed glycerol-based organosolv with solvent recycling, Res. in press (2020).
  3. Kimura et al., Production of antiviral substance from sugarcane bagasse by chemical alteration of its native lignin structure through microwave solvolysis, ChemSusChem, 13: 4519-4527 (2020).

Research 5: Development of high-strength products based on cellulose and chitin nanofibers

RISH investigators: Hiroyuki Yano, Kentaro Abe

In order to promote the widespread utilization of cellulose, we are developing a high-strength cellulose composite material consisting of different cellulose materials (wood pulp, cellulose nanofibers and dissolved/regenerated cellulose). We are aiming to manufacture food packaging and three-dimensional molded products from cellulose alone, but the problem is water resistance. Normally, the water resistance is improved by using a polyamide amine epichlorohydrin resin or the like, but in this study, the water resistance is overcome by performing cross-linking between pulps with cellulose nanofibers (Figure).
In the future, we will conduct biodegradability surveys and manufacture environmentally friendly molded products with the aim of further increasing strength.

Figure: Effect of NaOH treatment on wet strength of “pulp + cellulose nanofibers” composite papers

 Selected Publications

  1. Yang et al. Strain-stiffening composite hydrogels through UV grafting of cellulose nanofibers, Cellulose, in press (2021).
  2. Abe et al. The reinforcement effect of cellulose nanofiber on Young’s modulus of polyvinyl alcohol gel produced through the freeze/thaw method. Polymer Res., 27: 241 (2020).
  3. Abe and Utsumi. Wet spinning of cellulose nanofibers via gelation by alkaline treatment, Cellulose, 27: 10441-10446 (2020).


Research 6: Development of energy storage device from biomass

RISH investigator(s): Toshimitsu Hata
Research collaborator(s): Lignyte Inc., Indonesian Institute of Science (LIPI), Osaka Prefecture University, etc.

Development of energy storage device from biomass is promising due to the view of renewability, low cost, and sustainability. An energy storage capacitor was developed by carbonizing and activating Abies sachalinensis as a raw material. KOH was added to the raw material, and carbonization and activation were carried out at 350 to 600°C. The resulting porous carbon was used as an energy storage capacitor. By applying the density functional theory (NLDFT) method to the CO2 gas adsorption isotherm at 0°C, the resulting porous carbon was found to have a relatively large surface area of 815 m2/g. Electrodes for electric double layer capacitors were prepared from the sample and electrochemical evaluation was performed.

Figure: Schematic diagram of charge discharge mechanism in electric double layer capacitor

Research 7: Micropore analysis of carbonized lignin for use in low earth orbit

RISH investigator(s): Toshimitsu Hata, Yuki Tobimatsu, Hirotsugu Kojima
Research collaborator(s): Kobe University、National Institute of Technology, Nagano College

Lignin with different aromatic structures from beech, cedar, and rice were prepared and observed for electron microscopy in order to investigate the possibility of using wood in the space environment. In order to investigate the resistance to atomic oxygen (AO), which is a problem in the low-orbit space environment, the microporous structures of the nanopores before and after carbonization were compared. The shrinkage of the pore size by carbonization was about 69%, and the main peak existed in the range of 0.37-0.44 nm. The main peak was found in the range of 0.37-0.44 nm. This indicates that AO adsorption is carried out by the nano-pores in response to short-term AO irradiation. On the other hand, the formation of a protective layer, such as SiO2, on the inner surface of the pores is effective for long-term exposure to AO, as inferred from the analysis of resistance data obtained for industrial lignin.

Figure: Research summary on carbonized lignin for use in low earth orbit

Research 8: Development of IoT technology with wireless power transfer via microwaves

RISH investigator(s): Naoki Shinohara, Tomohiko Mitani
Research collaborator(s): Panasonic Co., MinebeaAtsumi Inc., etc.

Toward a post-fossil-fuel society, IoT (Internet Of Things) technology for a sophisticated society is required. We are developing an unconscious wireless charging system and battery-less IoT sensor with wireless power transfer (WPT) via microwaves. As a result of WPT R&D, Ministry of Internal Affairs and Communications decided to revise a ministerial ordinance of radio waves in 2021. We, Kyoto University, Panasonic Co., and Kanazawa Inst. Tech. accelerate development of wireless powered vital sensors. Toward next step of new radio regulation of the WPT, Kyoto University and MinebeaMitsumi are developing microwave power aided sensor to investigate tunnel automatically from driving car and succeeded in field experiment in special religion for scientific experiment (Tokku) in November, 2020.

Fig. Developed 920MHz-Band Rectifier for Wireless Powered Vital Sensors

Selected Publications

  1. (Invited) Shinohara, N., “History and Innovation of Wireless Power Transfer via Microwave”, IEEE Journal of Microwave, Vol.1, No.1, pp.218-228, 2021, doi:10.1109/JMW.2020.3030896

+ 13 international journal papers

2019 Activity Report

Gokasho, Uji City, Kyoto Prefecture, Japan. 611-0011
Telephone: +774-38-3346 Facsimile: +774-38-3600