• Journal of Microbiology and Biotechnology
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• 제17권12호
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• pp.2081-2084
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• 2007

A 2.5 kb aga gene encoding ${\alpha}$-galactosidase (${\alpha}$-Gal) from Leuconostoc mesenteroides SY1 was cloned into pSJE, an E. coli-Leuconostoc shuttle vector. The recombinant plasmid, pSJEaga, was introduced into Leuconostoc citreum KCTC3526 (ATCC49370) by electroporation. Transcription level of aga was the highest in cells grown on raffinose (1%, w/v) followed by cells grown on galactose, melibiose, fructose, glucose, and sucrose. Western blot using antibodies against ${\alpha}$-Gal showed similar results to slot-blot results and enzyme activity measurements. All the results indicated that the aga was successfully expressed in L. citreum and its transcription was under the carbon catabolite repression (CCR).

• Journal of Microbiology and Biotechnology
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• 제17권11호
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• pp.1898-1903
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• 2007

We attempted to modulate the overall protein expression rate through the addition of a repressor against the araBAD promoter system of Escherichia coli, in which glucose was used as a repressor. Therefore, 0.5% L-arabinose was initially contained as an inducer in culture medium, and either 2% glucose or 2% glycerol was used as a carbon source, and it was found that the expression of recombinant interferon-${\alpha}$ could be observed at the beginning of the batch culture when glycerol was used as a carbon source. However, when glucose was used, the initiation of recombinant interferon-${\alpha}$ expression was delayed compared with that when glycerol was used. Furthermore, when the addition of 0.5% glucose was carried out once or twice after 0.5% L-arabinose induction during DO-stat fed-batch culture, the distributions of soluble and insoluble recombinant interferon-${\alpha}$ were modulated. When glucose was not added after the induction of L-arabinose, all of the expressed recombinant interferon-${\alpha}$ formed an inclusion body during the later half of culturing. However, when glucose was added after induction, the expressed recombinant interferon-${\alpha}$ did not all form an inclusion body, and about half of the total recombinant interferon-${\alpha}$ was expressed in a soluble form. It was deduced that the addition of glucose after the induction of L-arabinose might lower the cAMP level, and thus, CAP (catabolite activator protein) might not be activated. The transcription rate of recombinant interferon-${\alpha}$ in the araBAD promoter system might be delayed by the partial repression. This inhibition of the transcription rate probably resulted in more soluble interferon-${\alpha}$ expression caused by the reduction of the protein synthesis rate.

• 한국미생물·생명공학회지
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• 제17권5호
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• pp.461-467
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• 1989

Hansenula polymoypha의 배양조건과 배지의 탄소원에 따른 alcohol-oxidase의 생성능을 비교하기 위하여 H. polymorpha CBS 4732, H. polymorpha CBM 11, 그리고 H. polymorpha Cooney의 3균주에 대하여 실험하였다. 배양조건에 따른 효소생성은 glucose를 탄소원으로 첨가한 mineral salt medium에서 균체를 정상기까지 배양하여 methanol이 함유된 배지에서 재배양하는 2단계 배양법의 경우가 균체를 직접 methanol 배지에 배양한 경우보다 효율적이었으며 생성된 총효소량은 전자의 경우가 후자에 비해 1.9배정도 많았다. 다음 탄소원에 따른 효소생성능을 비교하였다. 먼저 직쇄 alcohol을 탄소원으로 사용한 경우 mothanol을 제외한 ethanol, propanol, butanoL, 그리고 pentanol에서는 효소가 생성되지 않았고 또한 이 직쇄 alcohol을 methanol과 혼합한 경우에도 극미량의 생성에 그쳤다. 여러 가지 탄소화합물 (glucose, xylose, lactose, glycerol, galactose, saccharose, sorbose, tactic acid acetic acid)을 탄소원으로 사용하면 methanol에 의해 생성된 효소량의 1/10 정도 생성되었고 이들을 methanol과 혼합사용하면 효소생성량은 급격히 증가하였고, 특히 lactose와 tactic acid의 경 우는 methanol 단독사용시 보다 오히려 다량 생성되었다. 시험 3균주 중에서는 어떤 경우에서든지 H. polymorpha CBS 4732가 alcohol-oxldase 생성능이 가장 좋은 것으로 나타났다.

• 한국미생물·생명공학회지
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• 제45권3호
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• pp.243-249
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• 2017

An agar-degrading bacterium, designated as the GNUM08123 strain, was isolated from samples of red algae collected from the Yongil Bay near East Sea, Korea. The isolated GNUM08123 strain was gram-negative, aerobic, motile, and beige-pigmented, with $C_{16:0}$ (25.9%) and summed feature 3 (comprising $C_{16:1}{\omega}7c/iso-C_{15:0}2-OH$, 34.4%) as its major cellular fatty acids. A similarity search based on the 16S rRNA gene sequence revealed that it belonged to class Gammaproteobacteria and shared 97.7% similarity with the type strain Vibrio chagasii $R-3712^T$. The DNA G+C content of strain $GNUM08123^T$ was 46.9 mol%. The major isoprenoid quinone was ubiquinone-8. The results of DNA-DNA relatedness and 16S rRNA sequence similarity analyses, in addition to its phenotypic and chemotaxonomic characteristics, suggest that strain GNUM08123 is a novel species within genus Vibrio, designated as Vibrio sp. GNUM08123. Agarase production by strain GNUM08123 was induced by agar and sucrose, but was repressed probably owing to carbon catabolite repression by glucose and maltose.

• 한국미생물·생명공학회지
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• 제41권1호
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• pp.8-16
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• 2013

An agar-hydrolyzing marine bacterium, strain GNUM08120, was isolated from Sargassum fulvellum collected from Yeongil bay of East Sea of Korea. The isolate was Gram-negative, aerobic, motile with single polar flagellum, and grew at 1-10% NaCl, pH 5.0-8.0, and $15-37^{\circ}C$. G+C content and the predominant respiratory quinone were 46.13 mol% and Q-8, respectively. The major cellular fatty acids were Summed feature 3 (24.5%), $C_{16:0}$ (21.7%), and $C_{18:1}{\omega}7c$ (12.5%). Based on 16S rRNA gene sequence similarity and DNA-DNA hybridization analyses, strain GNUM08120 was identified as a novel subspecies of Alteromonas macleodii, designated Alteromonas macleodii subsp. GNUM08120. Production of agarase by strain GNUM08120 was likely repressed by the effect of carbon catabolite repression caused by glucose. The crude agarase prepared from 12-h culture broth of strain GNUM08120 exhibited an optimum pH and temperature for agarase activity at 7.0 and $40^{\circ}C$, respectively. The crude enzyme produced (neo)agarobiose, (neo)agarotetraose, and (neo)agarohexaose as the hydrolyzed product of agarose.

• Applied Biological Chemistry
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• 제34권4호
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• pp.327-333
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• 1991

Cheddar치즈의 숙성기간을 단축시키고 flavor를 증진시킬 목적으로 단백분해력이 있는 Micrococcus sp. LL3를 Cheddar 치즈에 첨가하기 위하여 본 균의 최적배양을 위한 배지조성을 검토하였다. 탄소원으로는 glucose, mannose, fructose 등의 단당류가 양호하였으며, arabinose, xylose는 균의 성장을 심하게 저해하였다. 본 균주에서는 탄소원의 첨가에 의한 catabolite repression은 나타나지 않았다. 또한 질소원으로는 yeast extract 0.2%의 첨가가 균의 성장에 좋았으며, 무기 질소원 첨가시는 균의 성장이 감소하였다. 특히 urea를 첨가시 균의 성장에 심한 저해효과가 있었다. 본 균주는 NaCl 9%첨가시 까지도 균의 생육이 가능했으며, 특히 1%첨가시에는 균체생육 및 단백분해 효과가 다소 증가하였다. 무기염의 경우 $MgSO_4\;0.05%$, 아미노산은 glutamic acid 0.2%첨가시 효과가 좋았다. 그러나 비타민은 $0.1\;{\mu}g/ml$ 수준으로 첨가시에 균의 성장 및 단백분해 효과에 영향을 미치지 않았다.

• 생명과학회지
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• 제7권1호
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• pp.30-38
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• 1997

내열성 {\alpha}$-amulase를 생산하는 미생물을 분리하기 위하여 각종 분리원으로 시료를 채취하여 55$^{\circ}C$ 이상에서 생육하고 가장 내열성 {\alpha}$-amulase 생산능이 우수한 균주를 분리, 동정한 결과 thermophilic Bacilus 속으로 추정되었다. 균체생육과 효소생산의 최적온도는 60~$65^{\circ}C$였고, 초발 pH8.0에서 가장 높은 효소생산능을 보였다. {\alpha}$-amulase 생산에 가장 양호한 탄소원은 soluble starch, dextrin, prtato starch, corn starch 등의 다당류이었으며 glucose, fructose 등의 단당류에서는 효소생산이 미약하거나 억제를 받았다. {\alpha}$-amulase 생산에 가장 중요한 질소원은 yeast extract이었따. 0.1% $CaCl_2{\cdot}2H_2O$, 0.001%의 Tween-80의 첨가는 {\alpha}$-amulase 생산성을 증가시켰다. 본 공사균이 생산한 조효소액의 특성을 검토해 본 결과, 8$0^{\circ}C$에서 최적 효소활성을 보였으며, 10$0^{\circ}C$에서도 23%의 잔존활성을 나타내었다. 최적 pH는 5.0이었다. $Ca^{2+}$은 효소활성 증진에는 영향을 미치지 않았다. 공시균으로부터 분리한 genomic DNA를 중온성 BAcillus subtilis KCTC 1024에 형질전환시킨 결과, transformant는 wild type에 비하여 약 2배의 효소활성이 증가되었다.