• KSBB Journal
• /
• 제8권5호
• /
• pp.417-423
• /
• 1993

생촉매의 수분함량이 기상에서의 연속반응기의 성능에 미치는 영향을 물질전달제한에 대한 연구와 함께 조사하였다. 각각 46.2%와 37.2%의 수분을 함유한 생촉매가 알코올 옥시데이즈 효소의 엠버라이트 IRA-400에로의 고정화 및 저속의 탈수화에 따라 준비되어져, 컬럼에 채워졌다. 연속식 기상반응에서의 상대생산속도(RPR)와 아세트알데하이드 조성($X_p$) 및 전환율(X)이 비교되었고 37.2%의 경우가 46.2%의 경우보다 우수하였는데 이는 기상에서의 물질전달 향상에 따른 것으로 판단되었다.

• Journal of Microbiology and Biotechnology
• /
• 제30권2호
• /
• pp.244-247
• /
• 2020

We have expressed extracellular poly(3-hydroxybutyrate) (PHB) depolymerase of Ralstonia pickettii T1 on the Escherichia coli surface using Pseudomonas OprF protein as a fusion partner by C-terminal deletion-fusion strategy. Surface display of depolymerase was confirmed by flow cytometry, immunofluorescence microscopy and whole cell hydrolase activity. For the application, depolymerase was used as an immobilized catalyst of enantioselective hydrolysis reaction for the first time. After 48 h, (R)-methyl mandelate was completely hydrolyzed, and (S)-mandelic acid was produced with over 99% enantiomeric excess. Our findings suggest that surface displayed depolymerase on E. coli can be used as an enantioselective biocatalyst.

• 한국고분자학회:학술대회논문집
• /
• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
• /
• pp.253-253
• /
• 2006

DNA has not been played the role as a biocatalyst in evolutionary history, although RNA and protein function as a biocatalyst. DNA double helix structure is believed to be impossible to form intricate active enzymatic sites. In addition, the chemical stability of DNA prevents the ability from self-modifying reactions. However, recent development of DNA engineering enables to create artificial enzymatic ability of DNA (deoxyribozyme) such as RNA cleavage and DNA modification. We investigated optimal conditions for enzymatic activity of DNA-Pt complex, and compared it with that of horse radish peroxidase. We report here that base sequence of DNA, pH and temperature affect the enzymatic activity of DNA-Pt complex.

• Advances in Traditional Medicine
• /
• 제7권1호
• /
• pp.79-84
• /
• 2007

Urease was immobilized with calcium alginate by entrapment method in the form of spherical beads and stored in Tris/acetate buffer (pH 7.3) at $4^{\circ}C$. Urease immobilized at different concentration of alginate beads (3%, 4% and 5%) showed higher apparent $K_{m}$ values than the soluble urease. Furthermore, $K_{m}$ has been shown to be corelated with effective diffusion coefficient (De) at different concentration of alginate gel. The present study showed that diffusion and reaction contribute to control the overall rate.

• Molecules and Cells
• /
• 제28권4호
• /
• pp.369-373
• /
• 2009

Heterologous secretory expression of endoglucanase E (Clostridium thermocellum) and ${\beta}$-glucosidase 1 (Saccharomycopsis fibuligera) was achieved in Saccharomyces cerevisiae fermentation cultures as an ${\alpha}$-mating factor signal peptide fusion, based on the native enzyme coding sequence. Ethanol production depends on simultaneous saccharification of cellulose to glucose and fermentation of glucose to ethanol by a recombinant yeast strain as a microbial biocatalyst. Recombinant yeast strain expressing endoglucanase and ${\beta}$-glucosidase was able to produce ethanol from ${\beta}$-glucan, CMC and acid swollen cellulose. This indicates that the resultant yeast strain of this study acts efficiently as a whole cell biocatalyst.

• 한국생물공학회:학술대회논문집
• /
• 한국생물공학회 2005년도 생물공학의 동향(XVI)
• /
• pp.385-385
• /
• 2005

• Bulletin of the Korean Chemical Society
• /
• 제27권11호
• /
• pp.1885-1887
• /
• 2006

• Journal of Microbiology and Biotechnology
• /
• 제20권4호
• /
• pp.712-717
• /
• 2010

Cytochrome P450 enzymes (P450s) are involved in the synthesis of a wide variety of valuable products and in the degradation of numerous toxic compounds. The P450 BM3 (CYP102A1) from Bacillus megaterium was the first P450 discovered to be fused to its redox partner, a mammalian-like diflavin reductase. Here, we report the development of a whole-cell biocatalyst using ice-nucleation protein (Inp) from Pseudomonas syringae to display a hemeand diflavin-containing oxidoreductase, P450 BM3 (a single, 119-kDa polypeptide with domains of both an oxygenase and a reductase) on the surface of Escherichia coli. The surface localization and functionality of the fusion protein containing P450 BM3 were verified by flow cytometry and measurement of enzymatic activities. The results of this study comprise the first report of microbial cell-surface display of a heme- and diflavin-containing enzyme. This system should allow us to select and develop oxidoreductases containing heme and/or flavins into practically useful whole-cell biocatalysts for extensive biotechnological applications, including selective synthesis of new chemicals and pharmaceuticals, bioconversion, bioremediation, live vaccine development, and biochip development.

• Journal of Microbiology and Biotechnology
• /
• 제24권5호
• /
• pp.619-628
• /
• 2014

To identify lipase LipA (PFL_0617) from Pseudomonas protegens Pf-5, a lipA deletion mutant (Pf0617) and a complementary strain (Pf0617lipA) were constructed, and their effects on the lipase production were examined. Pf0617 remarkably decreased its whole-cell lipase activity, whereas Pf0617lipA made its whole-cell lipase activity not only restore to wild-type level but also get a further increment. However, the deletion and overexpression of lipA did not affect the extracellular lipase activity. In addition, the unbroken whole cells of these strains were able to catalyze the hydrolysis of membrane-permeable p-nitrophenyl esters, but could not hydrolyze the membrane-impermeable olive oil. These results confirmed that LipA was an intracellular lipase and Pf-5 could also be used as a natural whole-cell biocatalyst. To evaluate the potential of Pf-5 as a whole-cell biocatalyst and separately characterize the whole-cell LipA, the properties of the whole-cell lipases from Pf-5 and Top10lipA were characterized. The results demonstrated that both Pf-5 and Top10lipA exhibited high tolerance to alkaline condition, high temperature, heavy metal ions, surfactants, and organic solvents. Taken together, lipA can realize functional expression in E. coli Top10, and Pf-5 and Top10lipA as whole-cell biocatalysts may have enormous potential in applications.

• Journal of Microbiology and Biotechnology
• /
• 제28권8호
• /
• pp.1360-1366
• /
• 2018

The fungi associated with termites secrete enzymes such as laccase (multi-copper oxidase) that can degrade extracellular wood matrix. Laccase uses molecular oxygen as an electron acceptor to catalyze the degradation of organic compounds. Owing to its ability to transfer electrons from the cathodic electrode to molecular oxygen, laccase has the potential to be a biocatalyst on the surface of the cathodic electrode of a microbial fuel cell (MFC). In this study, a two-chamber MFC using the laccase-producing fungus Galactomyces reessii was investigated. The fungus cultured on coconut coir was placed in the cathode chamber, while an anaerobic microbial community was maintained in the anode chamber fed by industrial rubber wastewater and supplemented by sulfate and a pH buffer. The laccase-based biocathode MFC (lbMFC) produced the maximum open circuit voltage of 250 mV, output voltage of 145 mV (with a $1,000{\Omega}$ resistor), power density of $59mW/m^2$, and current density of $278mA/m^2$, and a 70% increase in half-cell potential. This study demonstrated the capability of laccase-producing yeast Galactomyces reessii as a biocatalyst on the cathode of the two-chamber lbMFC.