• Journal of Microbiology and Biotechnology
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• 제25권1호
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• pp.89-97
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• 2015

Bacillus subtilis HK176 with high fibrinolytic activity was isolated from cheonggukjang, a Korean fermented soyfood. A gene, aprE176, encoding the major fibrinolytic enzyme was cloned from B. subtilis HK176 and overexpressed in E. coli BL21(DE3) using plasmid pET26b(+). The specific activity of purified AprE176 was 216.8 ± 5.4 plasmin unit/mg protein and the optimum pH and temperature were pH 8.0 and 40℃, respectively. Error-prone PCR was performed for aprE176, and the PCR products were introduced into E. coli BL21(DE3) after ligation with pET26b(+). Mutants showing enhanced fibrinolytic activities were screened first using skim-milk plates and then fibrin plates. Among the mutants, M179 showed the highest activity on a fibrin plate and it had one amino acid substitution (A176T). The specific activity of M179 was 2.2-fold higher than that of the wild-type enzyme, but the catalytic efficiency (k_cat/K_m) of M179 was not different from the wild-type enzyme owing to reduced substrate affinity. Interestingly, M179 showed increased thermostability. M179 retained 36% of activity after 5 h at 45℃, whereas AprE176 retained only 11%. Molecular modeling analysis suggested that the 176^th residue of M179, threonine, was located near the cation-binding site compared with the wild type. This probably caused tight binding of M179 with Ca²⁺, whichincreased the thermostability of M179.

• 대한수의학회지
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• 제56권4호
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• pp.233-239
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• 2016

This study was conducted to analyze penicillin G (PEG), streptomycin (STR) and neomycin (NEO) residues in milk of healthy lactating cows. Milk samples were collected from all four quarters of 12 dairy cows 2−7 days after intramammary infusions of an ointment containing PEG, STR and NEO once (n = 4; group I) or twice (n = 4, group II) daily. Ultra-performance liquid chromatography coupled with electrospray tandem mass spectrometry was used to determine the antibiotic residues in the samples. The correlation coefficient ($r^2$) of the calibration curves for all antibiotics was > 0.999 and the limits of detection and quantification were $0.002-0.005{\mu}g/mL$ and $0.007-0.02{\mu}g/mL$, respectively. Recovery rates were ranged from 75.5 to 92.3%. In group I, PEG, STR and NEO residues were detected in milk at 2, 3 and 2 days post-treatment, respectively, which were below the maximum residue limit (MRL). In group II, PEG, STR and NEO residues were detected in milk at 2, 3 and 3 days post-treatment, respectively, which were bellow the MRL. These results suggest that a 3-day for milk withdrawal period after the ointment treatment might be sufficient for reduction of the antibiotic residues below the MRL.

• 한국해양바이오학회지
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• 제1권4호
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• pp.252-259
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• 2006

본 실험은 electron spin/paramagnetic resonance(ESR/EPR)를 이용하여 기존의 DPPH free radical 소거 활성을 측정하였고, 이를 해조류 유래 천연자원으로부터 새로운 항산화물질을 탐색하는데 적용해 보았다. 연구 결과, 녹조류 추출물에서는 참홑파래, 납작파래 및 청각의 고온 메탄올 추출물에서만 약간의 라디칼 소거활성을 나타내었고, 이 외의 추출물에서는 소거활성이 거의 보이지 않았다. 갈조류는 총 71개의 추출물 중 37개의 추출물에서 80% 이상의 소거율을 보여 아주 우수한 항산화 물질을 가진 family로 여겨지며, 특히 모자반류 (Sargassum spp.)는 수용성과 메탄올, 고온과 상온의 모든 추출물에서 높은 라디칼 소거 활성을 보여 앞으로의 신소재 물질 후보로 선별되었다. 홍조류에서는 수용성보다는 메탄올 추출물에서 대체적으로 높은 소거활성이 검색되어, 나중에는 유기용매 분획물을 제조하여 라디칼 소거능을 측정 할 수 있을 것이다. 이처럼 해조류는 라키칼 소거 능력을 가지는 성분을 여러 형태로 다량으로 함유 하고 있는 것으로 사료 되며 앞으로의 연구에 기대가치를 더해 줄 것으로 사료된다.

• EDISON SW 활용 경진대회 논문집
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• 제4회(2015년)
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• pp.14-23
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• 2015

Alzheimer's disease is one of the most common types of degenerative dementia. As a considerable cause of Alzheimer's disease, neurotoxic plaques composed of 39 to 42 residue-long amyloid beta($A{\beta}$) fibrils have been found in the patient's brain in large quantity. A previous study found that erythrosine B (ER), a red color food dye approved by FDA, inhibits the formation of amyloid beta fibril structures. Here, in an attempt to elucidate the inhibition mechanism, we performed molecular dynamics simulations to demonstrate the conformational change of $A{\beta}40$ induced by 2 ERs in atomistic detail. During the simulation, the ERs bound to the surfaces of both N-terminus and C-terminus regions of $A{\beta}40$ rapidly. The observed stacking of the ERs and the aromatic side chains near the N-terminus region suggests a possible inhibition mechanism in which disturbing the inter-chain stacking of PHEs destabilizes beta-sheet enriched in amyloid beta fibrils. The bound ERs block water molecules and thereby help stabilizing alpha helical structure at the main chain of C-terminus and interrupt the formation of the salt-bridge ASP23-LYS28 at the same time. Our findings can help better understanding of the current and upcoming treatment studies for Alzheimer's disease by suggesting inhibition mechanism of ER on the conformational transition of $A{\beta}40$ at the molecular level.

• Journal of Microbiology and Biotechnology
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• 제26권11호
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• pp.1845-1854
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• 2016

The transglycosylation activity of amylosucrase (ASase) has received significant attention owing to its use of an inexpensive donor, sucrose, and broad acceptor specificity, including glycone and aglycone compounds. The transglycosylation reaction of recombinant ASase from Deinococcus radiopugnans (DRpAS) was investigated using various phenolic compounds, and quercetin-3-O-rutinoside (rutin) was found to be the most suitable acceptor molecule used by DRpAS. Two amino acid residues in DRpAS variants (DRpAS Q299K and DRpAS Q299R), assumed to be involved in acceptor binding, were constructed by site-directed mutagenesis. Intriguingly, DRpAS Q299K and DRpAS Q299R produced 10-fold and 4-fold higher levels of rutin transglycosylation product than did the wild-type (WT) DRpAS, respectively. According to in silico molecular docking analysis, the lysine residue at position 299 in the mutants enables rutin to more easily position inside the active pocket of the mutant enzyme than in that of the WT, due to conformational changes in loop 4.

• Journal of Microbiology and Biotechnology
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• 제23권1호
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• pp.69-75
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• 2013

Enrofloxacin is a fluoroquinolone antibiotic approved for the treatment of infections in animals. Because of the side effects to consumers of animal products, the maximum residue limits (MRLs) of enrofloxacin in animal tissues for consumption are regulated. In this study, a monoclonal antibody (mAb) against enrofloxacin was prepared and characterized for the development of a direct competitive enzyme-linked immunosorbent assay (ELISA). The obtained mAb, Enro44, was highly specific for enrofloxacin and had a 50% inhibition concentration ($IC_{50}$) of 1.99 ng/ml in a competitive ELISA, and the limit of detection (LOD) was 0.50 ng/ml. The cross-reactivity of the mAb with other quinolones and fluoroquinolones was lower than 0.01%. The subclass of the mAb Enro44 was identified as IgG1. The antigen (Ag)-captured direct competitive ELISA using the mAb Enro44 was tested on different spiked samples, including chicken muscle, cattle milk, and cattle urine, and the assay demonstrated recoveries of 82-112%, 80-125%, and 78-124%, respectively. Furthermore, the quantitation of enrofloxacin obtained from the ELISA and from high-performance liquid chromatography (HPLC) was in good agreement, with the linear regression coefficient between 0.933 and 1.056. The cDNAs encoding a heavy-chain Fd fragment (VH and CH1) and a light chain of the mAb Enro44 were cloned and sequenced. Taken together, the results obtained reveal a potential use of this mAb in an ELISA for the detection of enrofloxacin in food samples. The information of amino acid sequence of this mAb will be useful for further modification and production of the mAb in a bioreactor.

• Journal of Ginseng Research
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• 제47권1호
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• pp.159-165
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• 2023

Background: Red ginseng marc, the residue of red ginseng left after water extraction, is rich in dietary fiber. Dietary fiber derived from fruits or vegetables can promote the proliferation of probiotics, and it is a key technology in the food industry to increase the productivity of probiotics by adding growth-enhancing substances such as dietary fiber. In this study, the effect of red ginseng dietary fiber (RGDF) on the growth of probiotic bacterial strains was investigated at the phenotypic and genetic levels. Methods: We performed transcriptome profiling of Lactiplantibacillus plantarum IDCC3501 in two phases of culture (logarithmic (L)-phase and stationary (S)-phase) in two culture conditions (with or without RGDF) using RNA-seq. Differentially expressed genes (DEGs) were identified and classified according to Gene Ontology terms. Results: The growth of L.plantarum IDCC3501 was enhanced in medium supplemented with RGDF up to 2%. As a result of DEG analysis, 29 genes were upregulated and 30 were downregulated in the RGDF-treated group in the L-phase. In the S-phase, 57 genes were upregulated and 126 were downregulated in the RGDF-treated group. Among the upregulated genes, 5 were upregulated only in the L-phase, 10 were upregulated only in the S-phase, and 3 were upregulated in both the L- and S-phases. Conclusions: Transcriptome analysis could be a valuable tool for elucidating the molecular mechanisms by which RGDF promotes the proliferation of L.plantarum IDCC3501. This growth-promoting effect of RGDF is important, since RGDF could be used as a prebiotic source without additional chemical or enzymatic processing.

• 농업과학연구
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• 제50권4호
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• pp.713-721
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• 2023

Soil acidification challenges global food security by adversely influences soil fertility and agricultural productivity. Carbonized agricultural residues present a sustainable and ecofriendly way to recycle agricultural waste and mitigate soil acidification. We evaluated the effects of organic amendments on lettuce growth and soil chemical properties in two soils with different pH levels. Carbonized rice husk was produced at 600℃ for 30 min and rice husk was treated at 1% (w·w^-1). Carbonized rice husk increased soil pH, electrical conductivity, total carbon content, and nitrogen content compared with untreated and rice husk treatments. Furthermore, this study found that lettuce growth positively correlated with soil pH, with increasing soil pH up to pH 6.34 resulting in improved lettuce growth parameters. Statistical correlation analysis also supported the relationship between soil pH and lettuce growth parameters. The study findings showed that the use of carbonized rice husk increased the constituent elements of lettuce, such as carbon, nitrogen, and phosphate content. The potassium content of lettuce followed a similar trend; however, was higher in acidic soil than that in non-acidic soil. Therefore, improving the pH of acidic soil is essential to enhance agricultural productivity. It is considered advantageous to use agricultural residues following pyrolysis to improve soil pH and agricultural productivity.

• 한국식품과학회지
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• 제39권2호
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• pp.114-121
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• 2007

서울지역에 유통되고 있는 국내산 및 수입산 건조농산물 58건을 대상으로 다성분 동시분석방법에 따라 GC-NPD, $GC-{\mu}ECD$, HPLC-UV와 HPLC-FLD로 분석가능한 총 253종의 농약잔류량을 분석한 후 GC-MSD로 확인한 결과 총 14건의 건조농산물에서 잔류농약이 검출되어 24.1%의 검출률을 나타내었고, 이 중 건조 채소류의 검출률은 25.5%였다. 품목별 잔류농약의 검출률은 건조과채류, 건조엽채류, 건조엽경채류 순으로 높았으며, 특히 건조 과채류 중 건조고추의 잔류농약 분포가 다양하고 검출빈도가 상당히 높았다. 건조 농산물의 기준에 없는 12종의 잔류농약이 검출되었으며, 합성피레스로이드계, 유기염소계, 유기인계 순으로 검출빈도가 높았고, 특히 합성피레스로이드계 중 cypermethrin의 검출 횟수가 가장 많았다. 또한 대상목적에 따라 분류하면, 살충제, 살균제, 제초제, 살선충제 순서로 검출건수가 많았다. 산지별로 보면, 국내산, 중국산 ,북한산, 미국산, 베트남산의 순서로 잔류농약의 검출건수가 많았으며, 국내산은 과채류에서 수입산은 엽경채류에서 잔류농약의 검출빈도가 높았다.

• 한국식품영양과학회지
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• 제42권2호
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• pp.262-267
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• 2013

본 연구는 당근(Daucus carota var. sativa) 가공방법 중 현재 주로 사용되고 있는 기계적 마쇄 공정으로 인하여 파괴되는 영양소의 손실을 최소화하기 위하여 식물 세포벽에 존재하는 불용성 물질인 protopectin을 가수분해하여 수용성 물질인 pectin으로 전환시키는 효소인 protopectinase를 이용하여 세포의 막을 보존하고 세포 안에 존재하는 영양소의 손실의 차이를 알아보고자 하였다. 당근의 회수율을 측정한 결과 효소처리군과 마쇄 공정 처리군을 비교하였을 때 효소처리군의 회수율은 81%, 잔사율은 19%을 보인 반면, 마쇄처리군은 회수율 56%, 잔사율 44%를 보여 약 20% 정도의 회수율 차이를 보였다. 이는 가공 후 수율 및 폐기량에서 많은 차이를 보일 것으로 판단된다. 당근의 효소 처리군과 마쇄 처리군의 성분 변화를 비교하기 위하여 당근의 주요성분인 ${\beta}$-carotene의 함량 변화를 측정한 결과 protection factor(PF) 각각 $2.2{\pm}0.2$ PF, $1.4{\pm}0.4$ PF의 차이를 보였으며, 총 폴리페놀 함량은 $89{\pm}3.42{\mu}g/g$, $64{\pm}4.16{\mu}g/g$, 총 플라보노이드 함량은 각각 $68{\pm}2.73\mu}g/g$, $41{\pm}3.26{\mu}g/g$을 보임으로써 세포막의 보존으로 인한 영양소의 파괴가 기계적 마쇄 처리군에 비하여 덜 발생한 것을 확인할 수 있었다. 두 처리군의 항산화력을 측정하기 위하여 DPPH radical 소거능과 hydroxyl radical 소거능, 아질산염 소거능을 측정하였으며 DPPH radical 소거능은 1,000 ppm에서 $87{\pm}0.29%$, $74{\pm}1.56%$로 약 13%의 DPPH radical 소거능을 보였고, hydroxyl radical 소거능 결과 10,000 ppm에서 $44{\pm}0.49%$와 $32{\pm}0.48%$로 약 12%의 hydroxyl radical 소거능을 보였다. 아질산염 소거능 측정 결과 1,000 ppm에서 $59{\pm}0.53%$와 $46{\pm}0.62%$로 약 13% 높은 아질산염 소거능을 보였다. 이는 protopectinase 효소 처리로 인한 세포막의 보존이 가공 중 발생되는 영양소의 손실을 줄임과 동시에 당근이 가지고 있는 항산화 물질들을 보존하고 있음을 확인할 수 있었다.