• Journal of Microbiology and Biotechnology
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• 제19권10호
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• pp.1077-1084
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• 2009

A genomic library was constructed to clone a xylanase gene (Mxyn10) from Demequina sp. JK4 isolated from a deep sea. Mxyn10 encoded a 471 residue protein with a calculated molecular mass of 49 kDa. This protein showed the highest sequence identity (70%) with the xylanase from Streptomyces lividans. Mxyn10 contains a catalytic domain that belongs to the glycoside hydrolase family 10 (GH10) and a carbohydrate-binding module (CBM) belonging to family 2. The optimum pH and temperature for enzymatic activity were pH 5.5 and $55^{\circ}C$, respectively. Mxyn10 exhibited good pH stability, remaining stable after treatment with buffers ranging from pH 3.5 to 10.0. The protein was not significantly affected by a variety of chemical reagents, including some compounds that usually inhibit the activity of other related enzymes. In addition, Mxyn10 showed activity on cellulose. These properties mark Mxyn10 as a potential enzyme for industrial application and saccharification processes essential for bioethanol production.

• Applied Biological Chemistry
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• 제36권6호
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• pp.539-546
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• 1993

본 연구에서는 Cheddar 치즈의 숙성기간을 단축시키고 flavor를 증진시키기 위하여 Micrococcus sp. LL3를 치즈 제조시에 첨가할 목적으로 본 균주가 생성하는 aminopeptidase의 특성을 조사하였으며, 또한 본 효소를 정제하였다. L-Leucine-p-nitroanilide를 기질로 사용 하였을 때 본 효소의 최적온도와 pH는 각각 $30^{\circ}C$ 및 7.0이었다. 본 효소는 $50^{\circ}C$까지의 온도에서 10분간 방치하였을 경우에도 안정하였다. $Mg^{++}$ ion에 의해 본 효소의 활성이 촉진되었으나 $Hg^{++}$ ion과 EDTA나 1,10-phenanthroline에 의해서 효소활성이 거의 실활되어 metallopeptidase인 것으로 추정되었다. 본 효소의 기실 특이성은 광범위 하였으나, N-terminal amino acid로서 arginine을 함유한 peptide는 분해하지 못했다. 본 균주가 생성하는 aminopeptidase의 정제를 위하여 DEAE-Sephacel ion chromatography및 gel filtration을 실시하였으며, 이때 분자량 46,500의 효소를 얻을 수 있었다.

• 한국식품위생안전성학회지
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• 제31권6호
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• pp.471-475
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• 2016

살모넬라증은 가축에 심각한 피해를 유발하는 질병으로, 축산업과 식품산업에 많은 경제적 손실을 초래하고 있다. 본 연구에서는, 복합 인산염을 주성분으로 하는 분말 소독제의 Salmonella Typhimuriums에 대한 살균효과 시험을 수행하였다. 배지희석법을 이용한 살균효력시험은 $4^{\circ}C$에서 30분 동안 시험 세균을 희석 소독제에 노출시켜 소독제의 가장 효과적인 낮은 희석배수를 결정하는 시험이다. 본 분말 소독제와 시험 세균을 처리조건에 따라 경수와 유기물로 희석하여 반응을 시켰다. 유기물 조건에서, Salmonella Typhimurium에 대한 소독제의 살균력은 경수조건에서의 살균력과 비교하여 낮게 나타났는데, 이는 유기물들에 의한 소독제의 살균 유효성분에 대한 저해작용에 따른 것으로 사료된다. 분말 소독제는 Salmonella Typhimurium과 같은 병원체에 대해 살균효과를 가지므로, 살모넬라증과 같은 세균성 질병의 확산을 제어하는데 효과적으로 이용될 수 있을 것으로 사료된다.

• Journal of Microbiology and Biotechnology
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• 제28권5호
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• pp.739-747
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• 2018

The low solubility and high-cost recovery of Propionibacterium acnes polyunsaturated fatty acid isomerase (PAI) are key problems in the bioproduction of high value-added conjugated linoleic acid (CLA). To improve the solubility of recombinant PAI, six chaperone proteins were coexpressed with PAI. Introduction of GroELS proteins dramatically improved the PAI solubility from 29% to 97%, with increased activity by 57.8%. Combined expression of DnaKJ-GrpE and GroELS proteins increased the activity by 11.9%. In contrast, coexpression of DnaKJ-GrpE proteins significantly reduced the activity by 57.4%. Plasmids pTf16 harboring the tig gene and pG-Tf2 containing the tig and groEL-groES genes had no visible impact on PAI expression. The lytic protein E was then introduced into the recombinant Escherichia coli to develop a cell autolysis system. A 35% activity of total intracellular PAI was released from the cytoplasm by suspending the lysed cells in distilled water. The PAI recovery was further improved to 81% by optimizing the release conditions. The lipase from Rhizopus oryzae was also expressed in E. coli, with an extracellular activity of 110.9 U/ml. By using the free PAI and lipase as catalysts, a joint system was established for producing CLA from sunflower oil. Under the optimized conditions, the maximum titer of t-10,c-12-CLA reached 9.4 g/l. This work provides an effective and low-cost strategy to improve the solubility and recovery of the recombinant intracellular PAI for further large-scale production of CLA.

• Journal of Microbiology and Biotechnology
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• 제12권6호
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• pp.921-928
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• 2002

Microorganism producing extracellular CFTase was isolated from soil and designated as Bacillus polymyxa MGL21. The gene encoding the CFTase (cft) from B. polymyxa MGL21 was cloned and sequenced. The ORF of the cf gene was composed of 3,999 nucleotides, encoding a protein (1,333 amino acids) with a predicted molecular mass of 149,375 Da. Sequence analysis indicated that CFTase was divided into five distinct regions. CFTase contained three regions of repeat sequences at the N-terminus and C-terminus. The endo-inulinase region of homology (ERH) of CFTase was similar to that of Pseudomonas mucidolens endo-inulinase ($50\%$ identity, 259 amino acids). Furthermore, CFTase possessed a highly conserved core region, which is considered to be functional for the hydrolysis reaction of inulin. The cft gene was expressed in a His-tagged form in Escherichia coli cells, and the His-tagged CFTase was purified to homogeneity. The optimal temperature and pH for CFTase activity were found to be $50^{\circ}C$ and 9.0, respectively. The enzyme activity was completely inhibited by 10 mM $Ag^+\;and\;Cu^2+$. Thin-layer chromatography analyses indicated that CFTase catalyzed not only the cyclization reaction ut also disproportionation and hydrolysis reactions as well.

• Journal of Microbiology and Biotechnology
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• 제25권7호
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• pp.953-962
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• 2015

Escherichia coli is the most preferred microorganism to express heterologous proteins for therapeutic use, as around 30% of the approved therapeutic proteins are currently being produced using it as a host. Owing to its rapid growth, high yield of the product, costeffectiveness, and easy scale-up process, E. coli is an expression host of choice in the biotechnology industry for large-scale production of proteins, particularly non-glycosylated proteins, for therapeutic use. The availability of various E. coli expression vectors and strains, relatively easy protein folding mechanisms, and bioprocess technologies, makes it very attractive for industrial applications. However, the codon usage in E. coli and the absence of post-translational modifications, such as glycosylation, phosphorylation, and proteolytic processing, limit its use for the production of slightly complex recombinant biopharmaceuticals. Several new technological advancements in the E. coli expression system to meet the biotechnology industry requirements have been made, such as novel engineered strains, genetically modifying E. coli to possess capability to glycosylate heterologous proteins and express complex proteins, including full-length glycosylated antibodies. This review summarizes the recent advancements that may further expand the use of the E. coli expression system to produce more complex and also glycosylated proteins for therapeutic use in the future.

• International Journal of Industrial Entomology and Biomaterials
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• 제33권1호
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• pp.1-5
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• 2016

Beauveria bassiana is a common fungal pathogen of Protaetia brevitarsis larvae, and although it is less common than Metarhizium anisopliae , the pathogen still poses a great risk to humans and animals that consume infected insects, owing to B. bassiana's production of toxins like beauvericin and mycotoxin. Interestingly, the beneficial microorganism Saccharomyces cerevisiae possesses antifungal properties. In the present study, we found that S. cerevisiae inhibited the growth of B. bassiana by 97% and that S. cerevisiae failed to harm P. brevitarsis when administered via intracoelomic injection (1×10⁷ cfu/mL). In addition, we also found that S. cerevisiae consumption increased the survival time of percutaneously infected P. brevitarsis larvae by 5 d and reduced the mortality of infected larvae by 12%. Therefore, S. cerevisiae is expected to be useful in the prevention and control of B. bassiana in the production of P. brevitarsis larvae.

• International Journal of Industrial Entomology and Biomaterials
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• 제36권1호
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• pp.1-9
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• 2018

The purpose of this study was to determine the best method for minimizing the occurrence of Metarhizium anisopliae infection of Protaetia brevitarsis seluensis during mass breeding on agricultural farms. There is a high demand for the use of P. b. seluensis larvae in animal feed and as food for humans. However, mass breeding results in the entomopathogenic fungal (usually M. anisopliae) infection of P. b. seluensis. A mixture of microorganisms (Bacillus subtilis, Lactobacillus plantarum, and Saccharomyces cerevisiae) delayed fungal infection by M. anisopliae, which infected fewer P. b. seluensis when the microorganism mixture was added to sawdust as feed for P. b. seluensis. When sawdust with the effective microorganisms (EM) was given to P. b. seluensis for 30 d, their mortality rate was approximately 35 % less than that of the control group, which was fed sawdust without the EM. In addition, the growth of M. anisopliae on agar media spread with each bacterium as inhibited by up to 80 % more than those spread with 4 % sodium hypochlorite, which is a harmless fungal inhibitor generally used in agricultural farms for disinfection.

• 공업화학
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• 제18권2호
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• pp.162-167
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• 2007

본 연구에서는 Clostridium beijerinckii Donker 1926을 이용한 연속식 혐기성 소화공정에서 수소 생산과 동력학적 특성을 고찰하였다. 기질은 glucose를 사용하였고, 0.5, 0.25, 0.125일의 체류시간 (hydraulic retention time, HRT)에서 실험이 이루어졌으며, 모든 HRT의 조건에서 탄산화물은 99% 이상의 제거효율를 나타내었다. 체류시간이 짧을수록, COD 제거율은 낮은 반면에, 전체 가스 중에서 수소 가스 함량과 수소 발생량이 높게 나타났다. 또한, 정상상태에서, 증식 수율과 수소가스 생성 수율은 각각 0.27 g-VSS/g- glucose, 0.26 L/g-glucose로 나타났다. 본 실험에 사용된 균주를 glucose와 같이 당 성분이 함유된 폐수처리에 적용하면 수소를 생산할 수 있으며, 이러한 실험 결과들을 잘 활용하면 대체에너지로서, 실제적인 수소가스 생산 시스템에 적용할 수 있을 것이다.

• 한국식품조리과학회지
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• 제20권6호
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• pp.561-567
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• 2004

The purpose of this study was to investigate the effect of Paecilomyces japonica mycelia(PJM) on pH, titrable acidity and microbiological qualify of Jeungpyun(fermented rice cake). Jeungpyun prepared with $0\~\%$ of PJM stored at $5^{\circ}C\;and\;20^{\circ}C$ for 4 weeks and 7 days respectively. Before fermentation of Jeungpyun dough, viable cells of total bacterial counts(TBC), yeasts and lactic acid bacteria(LAB) were $6.0\~9.8\times10^6,\;5.3\~9.0\times10^6,\;5.4\~8.5\times10^6\;CFU/g$, respectively. During the fermentation of dough, viable cells of TBC, yeasts and LAB increased $0.3\~0.4$ log cycle and pH was decreased whereas acidity increased as the progress of fermentation. Total viable cells in Jeungpyun before storage were $5.0\times10^1\;CFU/g$. During storage of Jeungpyun, TBC, yeasts and LAB of control group increased 2.6, 2.4, 2.1 log cycle at $5^{\circ}C$ and 4.8, 4.6, 4.5 log cycle at $50^{\circ}C$, respectively, when reached at maximum level. Major microflora of Jeungpyun was composed of yeasts and LAB during fermentation of dough and storage at $5^{\circ}C\;and\;20^{\circ}C$. Addition of PJM, inhibited the growth of microorganisms, the changes of PH and titrable acidity of Jeungpyun during storage at both of $5^{\circ}C\;and\;20^{\circ}C$. From these results, the addition of PJM extended the shelf-life of Jeungpyun during storage at $5^{\circ}C\;and\;20^{\circ}C$.