Authorship：Lead author,　Corresponding author   Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

DOI： 10.1016/j.bbrc.2023.09.010

PubMed

Authorship：Corresponding author   Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

Alka(e)nes are high-value chemicals with a potentially broad range of industrial applications because of their following advantages: (1) chemical and structural resemblance to petroleum hydrocarbons and (2) higher energy density and hydrophobicity than those of other biofuels. The low yield of bio-alka(e)nes, however, hinders their commercial application. The activity and solubility of acyl carrier protein (ACP) reductase (AAR) affect alka(e)ne biosynthesis in cyanobacteria. The enhancement of the activity and concentration of soluble AAR through genetic and process engineering can improve bio-alka(e)ne yield. Although fusion tags are used to enhance the expression or solubility of recombinant proteins, their effectiveness in improving the production of bio-alka(e)nes has not yet been reported. Fusion tags can be used to improve the amount or activity of soluble AAR in Escherichia coli and to increase the yield of alka(e)nes in E. coli cells co-expressing aldehyde deformylating oxygenase (ADO). Hence, in the present study, histidine (His6/His12), thioredoxin (Trx), maltose-binding protein (MBP), and N-utilization substance (NusA) were used as AAR fusion tags. The strain expressing SeAAR with His12 tag and NpADO showed a 7.2-fold higher yield of alka(e)nes than the strain expressing AAR without fusion tag and NpADO. The highest titer of alka(e)nes (194.78 mg/L) was achieved with the His12 tag.

DOI： 10.1016/j.enzmictec.2023.110262

PubMed

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

DOI： 10.1007/s11274-022-03515-x

PubMed

Other URL： https://link.springer.com/article/10.1007/s11274-022-03515-x/fulltext.html

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

DOI： 10.1093/bbb/zbad021

PubMed

Authorship：Lead author,　Corresponding author   Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

DOI： 10.1016/j.bej.2022.108772

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

Authorship：Lead author   Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

DOI： 10.1016/j.bej.2022.108720

Authorship：Corresponding author   Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

DOI： 10.1016/j.bej.2022.108659

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

Owing to issues, such as the depletion of petroleum resources and price instability, the development of biorefinery related technologies that produce fuels, electric power, chemical substances, among others, from renewable resources is being actively promoted. 2,3-Butanediol (2,3-BDO) is a key compound that can be used to produce various chemical substances. In recent years, 2,3-BDO production using biological processes has attracted extensive attention for achieving a sustainable society through the production of useful compounds from renewable resources. With the development of genetic engineering, metabolic engineering, synthetic biology, and other research field, studies on 2,3-BDO production by the yeast, Saccharomyces cerevisiae, which is safe and can be fabricated using an established industrial-scale cultivation technology, have been actively conducted. In this review, we sought to describe 2,3-BDO and its derivatives; discuss 2,3-BDO production by microorganisms, in particular S. cerevisiae, whose research and development has made remarkable progress; describe a method for separating and recovering 2,3-BDO from a microbial culture medium; and propose future prospects for the industrial production of 2,3-BDO by microorganisms.

DOI： 10.1007/s11274-021-03224-x

PubMed

Kind of work：Joint Work  

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

Carotenoids are hydrophobic compounds that exhibit excellent bioactivity and can be produced by recombinant S. cerevisiae. Irradiating microorganisms with ultrasonic waves increase the productivity of various useful chemicals. Ultrasonic waves are also used to extract useful chemicals that accumulate in microbial cells. In this study, we aimed to improve the carotenoid production efficiency of a recombinant S. cerevisiae using an ultrasonic-irradiation based two-phase extractive fermentation process. When isopropyl myristate was used as the extraction solvent, a total of 264 mg/L of carotenoid was produced when batches were subjected to ultrasonic-irradiation at 10 W, which was a 1.3-fold increase when compared to the control. Transcriptome analysis suggested that one of the reasons for this improvement was an increase in the number of living cells. In fact, after 96 h of fermentation, the number of living cells increased by 1.4-fold upon irradiation with ultrasonic waves. Consequently, we succeeded in improving the carotenoid production in a recombinant S. cerevisiae strain using a ultrasonic-irradiated two-phase extractive fermentation and isopropyl myristate as the solvent. This fermentation strategy has the potential to be widely applied during the production of hydrophobic chemicals in recombinant yeast, and future research is expected to further develop this process.

DOI： 10.1002/elsc.202100051

PubMed

Publishing type：Research paper (scientific journal)   International / domestic magazine：Domestic journal  

Although the yeast Saccharomyces cerevisiae has been used to produce various bio-based chemicals, including solvents and organic acids, most of these products inhibit yeast growth at high concentrations. In general, it is difficult to rationally improve stress tolerance in yeast by modifying specific genes, because many of the genes involved in stress response remain unidentified. Previous studies have reported that various forms of stress tolerance in yeast were improved by introducing random mutations, such as DNA point mutations and DNA structural mutations. In this study, we developed a novel mutagenesis strategy that allows for the simultaneous performance of these two types of mutagenesis to construct a yeast variant with high 2,3-butanediol (2,3-BDO) tolerance. The mutations were simultaneously introduced into S. cerevisiae YPH499, accompanied by a stepwise increase in the concentration of 2,3-BDO. The resulting mutant YPH499/pol3δ/BD_392 showed 4.9-fold higher cell concentrations than the parental strain after 96 h cultivation in medium containing 175 g/L 2,3-BDO. Afterwards, we carried out transcriptome analysis to characterize the 2,3-BDO-tolerant strain. Gene ontology enrichment analysis with RNA sequence data revealed an increase in expression levels of genes related to amino acid metabolic processes. Therefore, we hypothesize that the yeast acquired high 2,3-BDO tolerance by amino acid function. Our research provides a novel mutagenesis strategy that achieves efficient modification of the genome for improving tolerance to various types of stressors.

DOI： 10.1016/j.jbiosc.2020.11.004

PubMed

Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.procbio.2021.01.005

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

Although, yeast Saccharomyces cerevisiae is expected to be used as a host for lactic acid production, improvement of yeast lactic acid tolerance is required for efficient non-neutralizing fermentation. In this study, we optimized the expression levels of various transcription factors to improve the lactic acid tolerance of yeast by a previously developed cocktail δ-integration strategy. By optimizing the expression levels of various transcription factors, the maximum D-lactic acid production and yield under non-neutralizing conditions were improved by 1.2. and 1.6 times, respectively. Furthermore, overexpression of PDR3, which is known as a transcription factor involved in multi-drug resistance, effectively improved lactic acid tolerance in yeast. In addition, we clarified for the first time that high expression of PDR3 contributes to the improvement of lactic acid tolerance. PDR3 is considered to be an excellent target gene for studies on yeast stress tolerance and further researches are desired in the future.

DOI： 10.1007/s11274-020-02977-1

PubMed

Kind of work：Joint Work  

Kind of work：Joint Work  

Kind of work：Joint Work  

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

Lactic acid (LA) is chemically synthesized or fermentatively produced using glucose as substrate, mainly using lactic acid bacteria. Polylactic acid is used as a biodegradable bioplastic for packaging materials, medical materials, and filaments for 3D printers. In this study, we aimed to construct a LA-tolerant yeast to reduce the neutralization cost in LA production. The pHLA2-51 strain was obtained through a previously developed genome evolution strategy, and transcriptome analysis revealed the gene expression profile of the mutant yeast. Furthermore, the expression of the genes associated with glycolysis and the LA synthesis pathway in the LA-tolerant yeast was comprehensively and randomly modified to construct a D-LA-producing, LA-tolerant yeast. In detail, DNA fragments expressing thirteen genes, HXT7, HXK2, PGI1, PFK1, PFK2, FBA1, TPI1, TDH3, PGK1, GPM1, ENO2, and PYK2, and D-lactate dehydrogenase (D-LDH) from Leuconostoc mesenteroides were randomly integrated into the genomic DNA in the LA-tolerant yeast. The resultant engineered yeast produced about 33.9 g/L of D-LA from 100 g/L glucose without neutralizing agents in a non-neutralized condition and 52.2 g/L of D-LA from 100 g/L glucose with 20 g/L CaCO3 in a semi-neutralized condition. Our research provides valuable insights into non-neutralized fermentative production of LA. KEY POINTS: • Lactic acid (LA) tolerance of yeast was improved by genome evolution. • The transcription levels of 751 genes were changed under LA stress. • Rapid LA production with semi-neutralization was achieved by modifying glycolysis. • A versatile yeast strain construction method based on the CRISPR system was proposed.

DOI： 10.1007/s00253-020-10906-3

PubMed

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

Microbial production of mevalonate from renewable feedstock is a promising and sustainable approach for the production of value-added chemicals. We describe the metabolic engineering of Escherichia coli to enhance mevalonate production from glucose and cellobiose. First, the mevalonate-producing pathway was introduced into E. coli and the expression of the gene atoB, which encodes the gene for acetoacetyl-CoA synthetase, was increased. Then, the deletion of the pgi gene, which encodes phosphoglucose isomerase, increased the NADPH/NADP+ ratio in the cells but did not improve mevalonate production. Alternatively, to reduce flux toward the tricarboxylic acid cycle, gltA, which encodes citrate synthetase, was disrupted. The resultant strain, MGΔgltA-MV, increased levels of intracellular acetyl-CoA up to sevenfold higher than the wild-type strain. This strain produced 8.0 g/L of mevalonate from 20 g/L of glucose. We also engineered the sugar supply by displaying β-glucosidase (BGL) on the cell surface. When cellobiose was used as carbon source, the strain lacking gnd displaying BGL efficiently consumed cellobiose and produced mevalonate at 5.7 g/L. The yield of mevalonate was 0.25 g/g glucose (1 g of cellobiose corresponds to 1.1 g of glucose). These results demonstrate the feasibility of producing mevalonate from cellobiose or cellooligosaccharides using an engineered E. coli strain.

DOI： 10.1002/bit.27350

PubMed

Other URL： https://onlinelibrary.wiley.com/doi/full-xml/10.1002/bit.27350

Kind of work：Joint Work  

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

Patchoulol is a sesquiterpene alcohol found in the leaves of the patchouli plant that can be extracted by steam distillation. Notably, patchoulol is an essential natural product frequently used in the chemical industry. However, patchouli produces an insignificant amount of patchoulol, not to mention steam distillation, and requires a lot of energy and time. Recombinant microorganisms that can be cultured in mild conditions and can produce patchoulol from renewable biomass resources may be a promising alternative. We previously developed the global metabolic engineering strategy (GMES), which produces a comprehensive metabolic modification in yeast, using the cocktail δ-integration method. In this study, we aimed to produce patchoulol by modifying engineered yeast. The expression of nine genes involved in patchoulol synthesis was modulated using GMES. Regarding patchoulol production, the resultant strain, YPH499/PAT167/MVA442, showed a concentration of 42.1 mg/L, a production rate of 8.42 mg/L/d, and a yield of 2.05 mg/g-glucose, respectably. These concentration values, production rate, and yield obtained through batch-fermentation in this study were high level when compared to previously reported recombinant microorganism studies. GMES could be used as a potential strategy for producing secondary metabolites from plants in recombinant Saccharomyces cerevisiae.

DOI： 10.1002/bit.27284

PubMed

Kind of work：Joint Work  

Kind of work：Joint Work  

Publishing type：Research paper (scientific journal)   International / domestic magazine：Domestic journal  

Bioamination methods using microorganisms have attracted much attention because of the increasing demand for environmentally friendly bioprocesses. n-Butylamine production from glucose in Escherichia coli was demonstrated in this study, which has never been reported because of the absence of n-butylamine-producing pathway in nature. We focused on a transaminase-mediated cascade for bioamination from an alcohol or aldehyde. The cascade can convert an alcohol or an aldehyde to the corresponding amine with l-alanine as an amine donor. Here, n-butyraldehyde, which is a metabolic intermediate in the n-butanol producing pathway, is a potential intermediate for producing n-butylamine using this cascade. Hence, the n-butanol-producing pathway and the transaminase-mediated cascade were combined into a synthetic metabolic pathway for producing n-butylamine from glucose. Firstly, we demonstrated the conversion of n-butanol to n-butylamine using a three enzyme-mediated cascade. n-Butanol was successfully converted to n-butylamine in 92% yield in the presence of l-alanine and ammonium chloride. Then, the n-butanol-producing pathway and transaminase-mediated cascade were introduced into E. coli. Using this system, n-butylamine was successfully produced from glucose as a carbon source at a concentration of 53.2 mg L-1 after 96 h cultivation using a ppc (phosphoenolpyruvate carboxylase)-deficient strain. To the best of our knowledge, this is the first report of the direct production of n-butylamine from glucose, and may provide a starting point for the development of microbial methods to produce other bioamines.

DOI： 10.1016/j.jbiosc.2019.06.015

PubMed

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

A thermostable lipase from Bacillus thermocatenulatus was glycosylated by forming the consensus sequence (-NXS/T-) for N-linked glycosylation by site-directed mutagenesis. Among the eight BTL2 mutants including the consensus sequence, six BTL2 mutants, A277 N, A290 N, Y200 N, T236 N, T238 N, and P261 N, were glycosylated. Among the six mutants, glycosylated A277 N and T236 N showed higher stability in the presence of 25% (v/v) DMSO (74.3 and 72.8% of initial activity was remained after incubation at 45 °C for 20 h, respectively) than deglycosylated A277 N and T236 N (57.2 and 45.1% of initial activity was remained, respectively). These glycosylated mutants also showed higher remaining activity than wild-type BTL2 (56.0% of the initial activity were remained). Furthermore, the glycosylated mutant T236 N showed longer half-lives in the presence of 25% (v/v) ethylene glycol, DMSO, and DMF (161, 133, and 56.7 h at 45 °C, respectively) than deglycosylated mutant T236 N (107, 91.9, and 42.8 h, respectively). N-linked glycosylation may be a promising approach for preparing enzymes to retain their activity in the presence of organic solvents.

DOI： 10.1016/j.enzmictec.2019.109416

PubMed

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

Lipase is a lipolytic enzyme that catalyzes the hydrolysis of lipids and esterification reactions. Lipase has been utilized in industrial uses, food processing, and therapeutic applications as a biocatalyst. However, substrates of lipase are often insoluble in water, and this problem limits its utility. Lipases are also used in organic solvents where the solvent-stability of lipase is an important factor. There is a huge number of approaches that can be undertaken to improve the organic solvent-stability of lipases. For example, screening of solvent-tolerant lipase in nature and direct evolution of lipase using genetic engineering are some of the employed approaches. Here, we focus on approaches based on the chemical treatment of lipases for modification and immobilization. The solvent-stability of lipase was improved by the attachment of other molecules, such as surfactants, polymers, and carbohydrates. The immobilization of the enzyme is been known to be an effective approach for not only recycling the enzyme but also its stabilization. Several reports have demonstrated that the solvent-stability of lipase is also improved by immobilization. In this review, we provide an overview of the approaches used to improve the solvent-stability of lipase.

DOI： 10.1007/s11274-019-2777-8

PubMed

Kind of work：Joint Work  

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

In this study, a commercial lipase derived from Candida cylindracea was chemically modified with dextran by conjugating ε-amine in the lysine residue with the carbonyl residue in oxidized dextran using the borane-pyridine complex as a reducing agent to increase the hydrophilicity of the microenvironment around the lipase in the presence of organic solvents. The degree of modification (53.2%), amount of dextran (0.66 g/g-lipase), specific activity (similar to that of the unmodified lipase), and stability in the presence of ethanol and 2-propanol (the half-lives were 2.24 and 1.86 times longer than those of the unmodified lipase) were higher for the lipase modified at pH 8.0 than for the lipases modified at other pH levels. Following modification with dextran at pH 8.0, the stability of the modified lipase was higher than that of the unmodified lipase in the presence of 25% (v/v) DMSO, ethanol, 2-propanol, toluene, n-hexane, and isooctane (the half-lives were 1.45, 2.24, 1.86, 1.76, 2.67 and 2.95 times longer than those of the unmodified lipase). Therefore, chemical modification with polysaccharides such as dextran using the borane-pyridine complex as a reducing agent could be a promising approach for improving the organic solvent stability of enzymes.

DOI： 10.1016/j.jbiotec.2019.02.009

PubMed

Kind of work：Joint Work  

Kind of work：Joint Work  

Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.bej.2018.11.003

Kind of work：Joint Work  

Presentation type：Poster presentation  

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Presentation type：Poster presentation  

Presentation type：Poster presentation  

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Presentation type：Poster presentation  

Presentation type：Oral presentation (invited, special)  

Presentation type：Poster presentation  

Presentation type：Poster presentation  

Presentation type：Poster presentation  

Presentation type：Poster presentation  

Presentation type：Poster presentation  

Presentation type：Poster presentation  

Presentation type：Poster presentation  

Presentation type：Poster presentation  

Presentation type：Poster presentation  

Presentation type：Poster presentation  

Presentation type：Poster presentation  

Presentation type：Poster presentation  

Presentation type：Oral presentation (invited, special)  

Presentation type：Poster presentation  

ケミカルエンジニアリングプラクティス指針書作成

化学工学実験I指針書作成

ケミカルエンジニアリングプラクティス指針書 作成

化学工学実験I指針書作成

ケミカルエンジニアリングプラクティス指針書

化学工学実験II指針書作成