Hitomi Ohara

Pineapple leaf fibers (PALF) were extracted by high-pressure water (HPW) using a household car washer with a cyclone jet nozzle. High-pressure water was sprayed along the leaf, which was secured on a concrete surface 7 cm away from the nozzle, extracting 3.0% fiber from a 36-cm section in 20 s. The PALF phase was observed by scanning electron microscopy, revealing that fibers obtained by HPW had almost no surface adhesions, while those obtained using decorticator machines had many scale-like attachments. No difference was observed in the fracture strain; however, the HPW-extracted fibers had a higher elastic modulus and maximum stress. The measured α-cellulose content for the fibers was 71.2 ± 0.8% for HPW and 55.4 ± 0.1% for the decorticator machine. The lignin coloration images showed that lignin remained in the PALF extracted by the decorticator machine, whereas no lignin residue was observed in the PALF extracted by HPW. The absolute CIE tint index (TCIE) value for the HPW sample, recorded at 10°-view angle, was lower than that for the decorticator sample, indicating that the HPW samples were closer to white and exhibited a lighter tint than the decorticator sample.

This study examined the feasibility of using Cellulomonas fimi and Shewanella oneidensis as microbial fuel cells fueled by starch, cellulose, chitin, and chitosan. To our knowledge, this is the first report of power generation using C. fimi fueled by these polysaccharides other than cellulose, furthermore the first report of S. oneidensis fueled by chitosan. No differences were observed in the power generation capacities between C. fimi and S. oneidensis when chitin and chitosan were used. However, C. fimi demonstrated effective power generation from starch and cellulose, showing a maximum current density of 17.4 mA m⁻² for starch and 38.8 mA m⁻² for cellulose. S. oneidensis could not utilize these fuels to generate electricity. Power generation using C. fimi fueled by starch and cellulose produced acetic acid, lactic acid, and formic acid. However, when chitin and chitosan were used, only acetic acid was produced. These results indicate that electron transfer from C. fimi to the anode may be inefficient. The accumulation of organic acid in the anode solution indicates insufficient electron transfer to the anode. To improve power generation efficiency, it may be necessary to enhance electron transfer from the cells to the anode, for example, by adding a mediator.

Objectives A bipolar membrane microbial fuel cell (bMFC) is used to generate electricity using cellulose in phosphate buffer solution as fuel, and the mechanism of electricity generation is elucidated from five reference experiments. Results The bMFC was operated for 20 days using cellulose as fuel and Cellulomonas fimi. In the first reference experiment, no microorganism was used. In the second experiment, a cation-exchange membrane was used instead of a bipolar membrane. In the third experiment, the bipolar membrane was used in the opposite orientation as in the main experiment. In the fourth experiment, D₂O was used instead of H₂O in the cathode chamber. In the final experiment, the tris-maleate buffer was used instead of a phosphate buffer. Sufficient power generation did not occur in either reference experiment. Conclusions The bMFC continuously generated electricity for 20 days, and elucidated H⁺ and OH⁻ react in bipolar membrane, where the counter cation of dihydrogen phosphate served as the final electron acceptor.

Glyoxylates are essential intermediates in several metabolic pathways and have a broad range of industrial applications. In this study, we propose a novel method for producing glyoxylate from glucose using engineered Escherichia coli BW25113. To direct the production of glyoxylate from glucose, malate synthase A (aceB), malate synthase G (glcB), glyoxylate carboligase (gcl), and glyoxylate/hydroxypyruvate reductase A (ycdW) genes were disrupted, and the glyoxylate shunt was reinforced in the disruptants by the overexpression of citrate synthase (gltA) and isocitrate lyase (aceA). In flask cultivation using M9 medium supplemented with 1% glucose, the disruptant E. coli BW25113 ΔaceB ΔglcB Δgcl ΔycdW produced 0.93 ± 0.17 g/L of glyoxylate. Further overexpression of gltA and aceA in the disruptant resulted in an improvement in glyoxylate production to 1.15 ± 0.02 g/L. By expressing a heterologous gene, pyc, in the engineered E. coli, the accumulation of intracellular oxaloacetate remarkably improved, leading to glyoxylate production of up to 2.42 ± 0.00 g/L with specific productivity at 4.22 ± 0.09 g/g-cell. To date, this is the highest reported titer and specific productivity of glyoxylate in E. coli.

In this paper, we presented a novel microbial fuel cell (bMFC) structure, with a bipolar membrane separating the anode and cathode chambers. A bipolar membrane divides the bMFC into anode and cathode chambers. The bipolar membrane comprises anion and cation exchange layers. The anode chamber side has the cation exchange layer, while the cathode chamber side has the anion exchange layer. The anode chamber of the bMFC was loaded with Shewanella oneidensis MR-1 and lactic acid, while the cathode chamber was loaded with pure water and iron (III) hydroxide. The bMFC generated electrons for 20 days at a maximum current density of 30 mA/m² and the ohmic resistance value was estimated to be 500 Ω. During the operation of the bMFC, both the anode and cathode chambers kept anaerobic conditions. There was no platinum catalyst in the cathode chamber, which is required for the reaction of protons with oxygen. Therefore, oxygen could not serve as an electron acceptor in the bMFC. We considered a bMFC mechanism in which protons produced by S. oneidensis react with hydroxide ions, the counter anions of Fe³⁺, inside the bipolar membrane to produce water. In other words, the electron acceptor in bMFC would be Fe³⁺.

Glycopolymers were successfully synthesised from unprotected sugars in aqueous media via a one-pot chemoenzymatic process of three reactions; the direct synthesis of 4,6-dimethoxy-1,3,5-triazin-2-yl glycosides from unprotected sugars, a glycosidase-catalysed glycosylation using the triazinyl glycoside to afford glycomonomers and a radical polymerisation. The resulting glycopolymers exhibited specific interactions with the corresponding lectin as glycoclusters.

The authors wish to make the following correction to this paper

Renewable vinyl compounds itaconic acid (IA) and its derivative 10-hydroxyhexylitaconic acid (10-HHIA) are naturally produced by fungi from biomass. This provides the opportunity to develop new biobased polyvinyls from IA and 10-HHIA monomers. In this study, we copolymerized these monomers at different ratios through free radical aqueous polymerization with potassium peroxodisulfate as an initiator, resulting in poly(IA-co-10-HHIA)s with different monomer compositions. We characterized the thermal properties of the polymers by thermogravimetric analysis (TGA) and Fourier-transform infrared spectroscopy (FT-IR). The nuclear magnetic resonance analysis and the gel permeation chromatography showed that the polymerization conversion, yield, and the molecular weights (weight-averaged Mw and number-averaged Mn) of the synthesized poly(IA-co-10-HHIA)s decreased with increasing 10-HHIA content. It is suggested that the hydroxyhexyl group of 10-HHIA inhibited the polymerization. The TGA results indicated that the poly(IA-co-10-HHIA)s continuously decomposed as temperature increased. The FT-IR analysis suggested that the formation of the hydrogen bonds between the carboxyl groups of IA and 10-HHIA in the polymer chains was promoted by heating and consequently the polymer dehydration occurred. To the best of our knowledge, this is the first time that biobased polyvinyls were synthesized using naturally occurring IA derivatives.