Methylcyclohexane production under fluctuating hydrogen flow rate conditions

Energy storage using liquid organic hydrogen carrier (LOHC) is a long-term method to store renewable energy with high hydrogen energy density. This study investigated a simple and low-cost system to produce methylcyclohexane (MCH) from toluene and hydrogen using fluctuating electric power, and developed its control method. In the current system, hydrogen generated by an alkaline water electrolyzer was directly supplied to hydrogenation reactors, where hydrogen purification equipment such as PSA and TSA is not installed to decrease costs. Hydrogen buffer tanks and compressors are not equipped. In order to enable MCH production using fluctuating electricity, a feed-forward toluene supply control method was developed and introduced to the system. The electrolyzer was operated under triangular waves and power generation patterns of photovoltaic cells and produced hydrogen with fluctuating flow rates up to 7.5 Nm³/h. Consequently, relatively high purity of MCH (more than 90% of MCH mole fraction) was successfully produced. Therefore, the simplified system has enough potential to produce MCH using fluctuating renewable electricity.     

Coexpression of platelet-derived growth factor receptor alpha and fetal liver kinase 1 enhances cardiogenic potential in embryonic stem cell differentiation in vitro

Nascent mesodermal cells derived from EB5 embryonic stem (ES) cells were sorted in terms of cardiogenic potential on the basis of their expression levels of platelet-derived growth factor receptor alpha (PDGFRalpha) and fetal liver kinase 1 (Flk-1). The sorted cells were cocultured with OP9 stromal cells to induce terminal differentiation into contractile cardiac colonies. A significant number of cardiac colonies were found in the Flk-1+/PDGFRalpha+ fraction. The enrichment double-positive fraction produced approximately fivefold more cardiac colonies than the Flk-1+/PDGFRalpha- fraction and 10-fold more than the Flk-1-/PDGFRalpha+ fraction. To investigate the involvement of these markers in embryonic cardiogenesis, the cells that disseminated from the E7.5-7.75 embryos were fractionated and seeded on OP9 cells. The cardiogenic potential was markedly enhanced in the Flk-1+/PDGFRalpha+ fraction. These results suggest that some of the precursor cells coexpressing these markers are selectively involved in cardiogenic events, and that the identification of ES-cell-derived precursors with these markers will contribute to the effective production of cardiomyocytes for cell therapies.     

Formation of the spore clumps during heat treatment increases the heat resistance of bacterial spores

Effects of the clumping of bacterial spores on their heat resistance as a result of heat treatment were investigated. Spore suspensions of Bacillus cereus, Bacillus coagulans and Bacillus licheniformis were heated at 85 degrees C. Survivor curves of the three strains showed tailing in all treatments after 30 min. As the treatment time increased, the formation of spore clumps increased in all strains after 20 min. Relative hydrophobicity of the spore surface increased as a result of heat treatment. The effect of spore concentration on the inactivation of the B. licheniformis spores was investigated, and surviving curves showed no tailing below a concentration of 4.9 log CFU/ml.     

Vacuolar H(+)-ATPase and plasma membrane H(+)-ATPase contribute to the tolerance against high-pressure carbon dioxide treatment in Saccharomyces cerevisiae

As a non-thermal sterilization process, high-pressure carbon dioxide treatment (HPCT) is considered to be promising. The main sterilizing effect of HPCT is thought to be acidification in cytoplasm of microorganisms. We investigated the tolerance mechanism of Saccharomyces cerevisiae to HPCT with special reference to vacuolar and plasma membrane H(+)-ATPases. HPCT was imposed at 35 degrees C, 4 to 10 MPa, for 10 min. slp1 mutant defective in vacuole morphogenesis was more sensitive to HPCT than its isogenic parent. Concanamycin A, a specific inhibitor of vacuolar H(+)-ATPase (V-ATPase), at 10 microM rendered the parent more HPCT-sensitive to the level of slp1. To confirm further the contribution of V-ATPase to the tolerance against HPCT in S. cerevisiae, we compared vma1 mutant of V-ATPase with its isogenic parent for their HPCT sensitivity. vma1 mutant was more sensitive to HPCT than its parent. Addition of 10 microM vanadate, an inhibitor of plasma membrane H(+)-ATPase (P-ATPase), to the wild type strains also increased the inactivation ratio. These results clearly show that V- and P-ATPases contribute to the tolerance against HPCT in S. cerevisiae by accumulating excess H(+) from cytoplasm to vacuole and excluding H(+) outside of the cell, respectively.     

Proposals for wastewater treatment by applying flocculating activity of cross-linked poly-gamma-glutamic acid

Cross-linked poly-gamma-glutamic acid (C-L gamma-PGA) markedly purified polluted water collected from rivers and ponds by flocculation and precipitation. This effect of C-L gamma-PGA occasionally required pretreatment with polyaluminum chloride (PAC). Components of polluted water in rivers or ponds are generally thought to be clay minerals, microorganisms and chemical compounds. In this study, the flocculating activities of C-L gamma-PGA against suspensions of bentonite, diatomaceous earth, Escherichia coli and Mycrocystis aeruginosa, and against solutions of crystal violet and bisphenol A were investigated. The mode of action of C-L gamma-PGA is thought to be based on electrostatic interaction between flocculants, C-L gamma-PGA and PAC, and the surface of polluted water components, which may lead to neutralization of the zeta-potential of those components.     

Characteristic Property of Low Bitterness in Protein Hydrolysates by a Novel Soybean Protease D3

ABSTRACT:  Enzymatic hydrolysis is 1 means of improving the functional properties of food protein; however, in most cases, bitter peptides are generated by such treatment, and the resulting product is therefore not acceptable as a food ingredient. We have already reported a novel cysteine protease, D3, purified from germinating soybean cotyledons. Because of its substrate specificities, most hydrophobic amino acid residues in the hydrolysate are presumed not to be located at the peptide termini. It was therefore expected that protein hydrolysate by protease D3 would taste less bitter than other enzymatic hydrolysates. The objective of this study was to demonstrate the low bitterness of protein hydrolysates by protease D3. For that purpose, soy protein and casein hydrolysates were prepared with treatment of protease D3, subtilisin, pepsin, trypsin, and thermolysin, respectively. The bitterness of these hydrolysates was evaluated by measuring points of subjective equality (PSE). The PSE value demonstrated that the protein hydrolysates by protease D3 were significantly less bitter than the other enzymatic hydrolysates, indicating that the products had a taste mild enough to be acceptable as a less-bitter peptide food ingredient. These results suggested that a prominent feature of protease D3 was its capacity to produce less-bitter peptides. Therefore, it is thought that protease D3 could be applied to produce protein hydrolysates for use as ingredients in a variety of food products.     

Accumulative gene integration into a pre-determined site using Cre/loxP

Site-specific gene recombination systems, such as Cre/loxP, have been used for genetic modification of cells and organisms in both basic and applied research. We previously developed an accumulative gene integration system (AGIS), in which target gene cassettes could be repeatedly integrated into a pre-determined site on a plasmid or cellular genome by recombinase-mediated cassette exchange (RMCE), using Cre and mutated loxPs. In the present study, we designed a simplified AGIS. For gene integration into a target site, the previous system used two loxP sites in the acceptor DNA, whereas the new system uses a single loxP site. The gene integration reactions were repeated four times in vitro using Cre protein and specific plasmids. The expected integration reactions mediated by Cre occurred at the loxP sites, resulting in integration of four target genes. The system was also used for genomic integration of reporter genes using Chinese hamster ovary (CHO) cells. The reporter genes were efficiently introduced into the CHO genome in a Cre-dependent manner, and transgene expression was detected after the integration reaction. The expression levels of the reporter genes were enhanced, corresponding to the increase of transgene copy number. Recombinase-mediated AGIS provides a useful tool for the modification of cellular genomes.