• 한국식품과학회지
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• 제16권2호
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• pp.143-148
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• 1984

본 연구에서는 SPC-yogurt에 첨가되는 여러가지 당(糖)과 발육촉진물이 L.acidophilus의 생육에 미치는 영향을 관찰하고, 제조된 yogurt의 flavor를 조사하였다. Soy milk를 SPC(단백질 4.2%)와 여러가지 당(糖) 및 발육촉진물질로 제조하였고 준비된 Soy milk 100ml를 적절히 가열살균후 24시간 배양된 유산균 2.5ml를 접종하고 $37^{\circ}C$에서 24시간 배양하였다. 유산출 생육의 정도는 생균수, 산도, pH로 판단하였다. 배양시간에 따른 유산균의 생육도를 측정한 실험으로부터 6시간까지가 log phase이고 30시간까지가 stationary phase인것으로 나타났다 본 실험에서 사용된 당(糖) 가운데 glucose와 fiuctose가 유산균에 의한 산생성에 현저한 효과를 보였으며. 그 적정농도는 가각 3%정도였다 첨가된 발육촉진물질가운데 yeast extract가 유산균에 의한 산의 생성을 가장 촉진시켰으며 그 적정 농도는 0.5% 정도였다 SPC의 농도가 증가함에 따라 제조된 soy yogurt의 산도가 다소 증가하였다.

• 생명과학회지
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• 제13권6호
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• pp.814-821
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• 2003

Heme 합성의 중간체이며 또한 광수용체로도 작용하는 protoporphyrin IX의 세포 내 농도 및 성장 배지에 존재하는 농도가 야생형 M. xanthus DK1622 균주로부터 측정되었다. Protoporphyrin IX의 세포 내 농도는 배양 시간이 경과함에 따라 계속 증가하여, 안정기에 최고치에 이르는 것으로 나타났다 안정기에 도달한 세포 내에는 6.4 picomoles/mg of protein의 protoporphrin IX이 존재하는 것으로 밝혀졌다. Protoporphyrin IX은 대수기 중간 시기부터 세포외로 분비가 시작되어, 안정기에 도달한 세포의 배양액에서는 세포의 단백질 대비하여 3.0 picomoles/mg of protein이 존재하는 것으로 측정되었다. 영양분의 고갈에 기인하여 형성된 포자에서도 protoporphyrin IX의 농도는 6.5 picomoles/mg of protein이 존재하는 것으로 관찰되었다. Succinylacetone을 $500\muM$ 농도로 성장 배지에 첨가하였을 경우에 protoporphyrin IX의 생산은 검출이 불가능할 정도로 방해를 받았으며, 세포성장이 저해되고 세포 성장은 정상의 절반 수준인 약 100 Klett unit에서 정지하는 것으로 나타났다. 하지만 포자의 형성은 succinylacetone의 첨가에 관계없이 89-100%의 생성율을 보였음으로 정상 농도의 protoporphyrin IX가 M. xanthus의 성장을 위해서는 중요하지만, 포자 형성 과정에 필수적인 것으로 보이지는 않는다. 안정기 세포에서 나타나는 photolysis 현상도 succinylacetone의 첨가 여부에 관계없이 유사한 수준으로 관찰되었다.

• 한국수산과학회지
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• 제32권6호
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• pp.791-797
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• 1999

Kluyveromyces fragilis (ATCC 36534)와 Candida utilis (ATCC 9950) 균주를 사료 첨가제와 rotifer 먹이로서 가치를 평가하기 위해 성장 단계별 및 세포벽의 화학처리에 따른 영양가를 분석하여 비교하였다. 조단백질 함량은 K. fragilis가 $48.2\~58.5\%$로 C. utilis의 $25.9\~43.4\%$보다 높은 경향을 보였고, 조지방 함량은 K. fragilis 및 C. utilis모두 $0.1\~1.6\%$로 매우 낮은 수준이었다. 조섬유의 함량은 두 효모에서 $0.6\~3.3\%$의 범위로 낮은 수준이었으며, protoplasted 효모의 경우는 다소 낮아지는 경향을 보였다. 효모종류에 따라 아미노산 조성이 다소 차이를 보였는데, Asp, Gly, Pro, Leu, Lys 및 Val은 K. fragilis가 C. utilis보다 그 함량이 높았으며, Glu 및 Arg은 C. utilis가 상대적으로 더 높은 경향을 보였다. 성장 단계별 아미노산 조성은 특별한 변화 경향이 없었으며, 세포 외벽을 처리한 protoplasted K. fragilis와 C. utilis의 Glu, Gly 및 Asg은 처리전보다 낮아지는 경향이었고, Leu, Phe 및 Val의 함량은 다소 높아진 것으로 나타났다. K. fragilis 및 C. utilis의 지방산은 대부분 $C_{18}$ 이하의 포화 또는 불포화산으로 구성되어 있었는데, 주로 $C_{16-18}$의 지방산들은 early log 또는 log phase에서 death phase로 갈수록, 그리고 protoplast에서 낮아지는 반면에 $C_{10-12}$와 같은 저급 지방산들은 증가하는 경향을 보였다. K. fragilis 및 C. utilis의 early log phase에서는 ATP 함량이 검출되지 않았지만, 그 후 단계 (log - death phase)에서 각각 증가하는 경향을 보였다 ADP 함량은 K. fragilis에서 early log phase 이후 단계부터 증가하였고, 세포막을 처리한 protoplast 상태에서는 높은 수준을 유지하였지만, C. utilis의 경우는 성장이 진행됨에 따라 감소하는 경향을 보였으며, protoplast 상태에서는 그 함량이 낮아지는 경향을 보였다. AMP 함량은 두 균주 모두 early log phase에서 낮은 수준이었지만, 그 후 단계에서는 높은 함량을 유지하였으며, protoplast 상태에는 검출되지 않았다 IMP 함량은 두 균주 모두 log phase에서 가장 높은 값을 보였으며, protoplast 상태에서는 낮은 값을 보였다. Inosine 함량은 K. fragilis의 성장이 진행됨에 따라 증가되었고, C. utilis에서는 K. fragilis보다 높은 경향이었으며, log phase에서 최대값을 보였다. 성장 단계별로 이들의 핵산관련물질의 총량은 두 균주 모두 early log phase에서 가장 낮은 값을 보였으며, 각 성장 단계별로 K. fragilis가 C. utilis보다 높은 값을 유지하였고. protoplast 상태에서는 C. utilis가 더 높은 값을 나타내었다.

• KSBB Journal
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• 제26권4호
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• pp.323-327
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• 2011

The convenient derivatization method of chiral amino alcohols as 9-anthraldimine Schiff base derivatives for chiral resolution was developed and the liquid chromatographic enantiomer separation of chiral amino alcohols as 9-anthraldimine derivatives was investigated on several coated and covalently bonded polysaccharide-derived chiral stationary phases (CSPs). In general, the performance of Chiralcel OD-H (or Chiralcel OD) (${\alpha}$ = 1.24-2.89), the coated CSP derived from cellulose derivative was superior to the other CSPs for resolution of 9-anthraldimine derivatives of several amino alcohols. The results of enantioseparation depending on the structure of 9-anthraldimine analytes like the steric bulky group and the polar moiety etc were discussed. The analytical method was applied to measure the enantiomeric purity of commercially available chiral amino alcohols. It is expected that the convenient analytical method will be very efficient for determination of enantiomeric purity of amino alcohols as 9-anthraldimine Schiff base derivatives with strong UV absorption.

• KSBB Journal
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• 제27권4호
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• pp.232-236
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• 2012

Comparative liquid chromatographic enantiomer separation of ${\alpha}$-amino acids, their esters and primary amino compounds was performed using two chiral stationary phases (CSPs) prepared by covalently bonding (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid (18-C-6-TA) of the same chiral selector. In general, the separation factors and resolution factors for these analytes on CSP 1 were greater than on CSP 2, while these capacity factors on CSP 2 were quite greater than on CSP 1. Except for leucine methyl ester and phenylalanine methyl ester, the elution orders of all analytes including ${\alpha}$-amino ${\alpha}$-alkyl acids and phenylglycine alkyl esters on CSP 1 are identical to those on CSP 2. This study showed that different connecting structures for these two CSPs might influence their ability to resolve the analytes depending on their structures related to the chiral recognition mechanism.

• Bulletin of the Korean Chemical Society
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• 제31권6호
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• pp.1551-1554
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• 2010

Two diastereomeric chiral stationary phases (CSPs) were applied to the liquid chromatographic resolution of various racemic ${\alpha}$-amino methyl esters, ${\alpha}$-amino N,N-diethylamides and ${\alpha}$-amino N-propylamides. The CSP incorporating (R)-3,3'-diphenyl-1,1'-binaphtyl and (R,R)-tartaric acid unit as chiral barriers did not show any chiral recognition. In contrast, the CSP incorporating (R)-3,3'-diphenyl-1,1'-binaphtyl and (S,S)-tartaric acid unit as chiral barriers was found to show excellent chiral recognition especially for the two enantiomers of ${\alpha}$-amino N-propylamides. Some of ${\alpha}$-amino methyl esters and ${\alpha}$-amino N,N-diethylamides were also resolved on the CSP incorporating (R)-3,3'-diphenyl-1,1'-binaphtyl and (S,S)-tartaric acid unit. From these results it was concluded that the two chiral units composing the diastereomeric CSPs can show "matched" or "mismatched" effect on the chiral recognition according to their absolute stereochemistry.

• 분석과학
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• 제36권4호
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• pp.143-151
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• 2023

Considering the greater role of α-amino acids in our daily lives, the enantiomer resolution of seven α-amino acids derivatized with fluorogenic reagent (4-fluoro-7-nitro-2,1,3-benzoxadiazole, NBD-F) by chiral HPLC on amylose or cellulose trisphenylcarbamate derived chiral stationary phases (CSPs) under simultaneous ultraviolet (UV) and fluorescence (FL) detection was performed. The degree of enantioseparation and resolution was affected by nature and selector backbones of the CSPs as well as the kind of amino acids. Baseline enantiomer separation and resolutions were observed for the enantiomers of all analytes as NBD derivatives especially on coated type amylose tris(3,5-dimethylphenylcarbamate) derived CSPs (Chiralpak AD-H and Lux Amylose-1). The other CSPs also showed good enantioselectivity except for the CSPs (Chiralpak IB, Chiralcel OD-H and Lux Cellulose-1) having cellulose tris(3,5-dimethylphenylcarbamate) as chiral selectors. The developed analytical chiral method was applied to determine the enantiomeric purity of seven commercially available L-α-amino acids and the impurities as D-forms were found to be in the range 0.08-0.87 %, respectively. The intra- and interday accuracy and precision assays showed high accuracy and precision of the developed analytical method. This chiral HPLC method for the enantiomer resolution of amino acids using fluorescent derivatization could be useful for the determination of enantiomeric purity of pharmaceuticals and biological study for amino acid type compounds among chiral drugs.

• Journal of Power Electronics
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• 제15권3호
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• pp.796-805
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• 2015

New direct and indirect current control methods for a fault-tolerant active power filter topology are presented in this paper. Since a three-phase four-switch topology has a phase bridge current which cannot be directly controlled, a hysteresis control method in the α-β plane which controls the three-phase current in the two-phase stationary coordinate system is proposed. The improved SVPWM algorithm is able to eliminate the operation of the trigonometric functions in the traditional algorithm by rotating the α-β coordinates and alternating the sequence of the output vectors, which in turn simplifies the algorithm and reduces the switching frequency. The selection of the DC-side reference voltage and DC-side capacitor equalization strategy are also discussed. Simulation and experiments demonstrate that the proposed control method is correct and feasible.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2001년도 추계학술발표대회
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• pp.545-548
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• 2001

Microbiologically influenced corrosion (MIC) of metal is common in the natural environment and sulfate reducing bacteria are representative microorganisms for MIC. We found that biofilm fomlation by SRB on the metal surface might be controlled by quorum sensing, which is a cell density dependent regulation of cell metabolism. As cell free culture fluids (spent media) of Desulfovibrio vulgaris and D. desulfuricans were tested for quontrn sensing related test strains, it was found that spent media of two SRB induced increased luminescence of Vibrio harveyi BB886 (sensor 1+, sensor 2-) and BB170 (sensor 1-, sensor 2+). Quorum activities of D. vulgaris and D. desulfuricans appeared to be parallel to growth patterns, i.e., it was low in the lag phase, highly increased in the exponential phase, and reached maximum in the stationary phase. Interestingly, however, luminescence of V. harveyi BB886 and BB170 induced by a unit cell mass of the SHB showed a maximal peak in the late lag phase. Hence, it was suspected that quorum sensing of these two SHB play unknown roles in shifting cells from dormant to growth stages.

• 한국환경과학회:학술대회논문집
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• 한국환경과학회 2008년도 추계학술발표회 발표논문집
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• pp.282-285
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• 2008

At least 15% of the C polykrikoides cells that precipitated to the bottom layer either by the addition of loess or no addition survived for 1 week at all growth phases, rather than disappearing immediately after precipitating. However, no live cells were observed after 20 days, regardless of phase or loess addition. In the exponential phase, the number of C polykrikoides cells increased to >2886 cells/ml after loess was added. However, in the stationary phase, the number of cells did not increase until 18 days. In the exponential phase, those C polykrikoides that survived precipitation caused by scattering loess on cultures did not appear to have the ability to cause red tides again because of the short red tide periods in the field, long lag time after loess addition, and low survival rate after loess addition.