• Journal of Microbiology and Biotechnology
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• 제15권6호
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• pp.1388-1391
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• 2005

Temporal changes of cell growth pattern and intracellular content of $\beta$-D-glucans were investigated with off-gas data in Agaricus blazei culture where glucose was intermittently fed. It was observed that the time point of carbon source depletion coincided with the point of sudden drop in the carbon dioxide evolution rate (CER), and that the sole supplementation of glucose was not enough to maintain active cell growth and glucan content. On the other hand, when yeast extract, a typical nitrogen source, was supplemented together with glucose when the CER suddenly dropped because of carbon source depletion, an active cell growth could be maintained until the end of the culture and the glucan content did not decrease with culture time, significantly enhancing glucan productivity.

• 한국미생물·생명공학회지
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• 제29권1호
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• pp.43-49
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• 2001

Indole and its derivatives form a class of toxic recalcitrant environmental pollutants, Abacte-rium, strain KL-9 was isolated from soil with indole as a sole source of carbon and nitrogen. KL-9 was identified as Acinetobacter sp. on the basis of 16 S rRNA gene sequence, fatty acid and quinone compositions. This identification was also confirmed by the ability of carbon source utilization and other biochemical tests. The growth of Acinetobacter sp. KL-9 was fastest with 0.3mg/ml of indole as was inhibited by higher than 0.5mg/ml of indole in the medium, KL-9 with indole also produced indigo. The formation of indigo was stimulated inthe presence of glucose, which is not a growth-suppoting carbon source for KL-9. Additional biotransformation evidence showed that anthranilate is an intermediate for the degradation of indole KL-9.

• Journal of Microbiology and Biotechnology
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• 제21권8호
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• pp.846-853
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• 2011

Glycerol has become an attractive carbon source in the biotechnology industry owing to its low price and reduced state. However, glycerol is rarely used as a carbon source in Saccharomyces cerevisiae because of its low utilization rate. In this study, we used glycerol as a main carbon source in S. cerevisiae to produce 1,2-propanediol. Metabolically engineered S. cerevisiae strains with overexpression of glycerol dissimilation pathway genes, including glycerol kinase (GUT1), glycerol 3-phosphate dehydrogenase (GUT2), glycerol dehydrogenase (gdh), and a glycerol transporter gene (GUP1), showed increased glycerol utilization and growth rate. More significant improvement of glycerol utilization and growth rate was accomplished by introducing 1,2-propanediol pathway genes, mgs (methylglyoxal synthase) and gldA (glycerol dehydrogenase) from Escherichia coli. By engineering both glycerol dissimilation and 1,2-propanediol pathways, the glycerol utilization and growth rate were improved 141% and 77%, respectively, and a 2.19 g 1,2- propanediol/l titer was achieved in 1% (v/v) glycerolcontaining YEPD medium in engineered S. cerevisiae.

• Journal of Microbiology and Biotechnology
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• 제8권1호
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• pp.14-20
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• 1998

Syntheses of the B. stearothermophilus xylanolytic enzymes such as xylanases, ${\beta}$-xylosidases, ${\alpha}$-arabinofurano-sidases, and esterases, were observed to be regulated by the carbon source present in the culture media. Xylan induced synthesis of ${\beta}$-xylosidase at the highest level while xylose gave about 30% of the ${\beta}$-xylosidase activity induced by xylan. The lowest syntheses of the xylanolytic enzymes above mentioned were detected in the basal medium containing glucose as a sole carbon source. When a mixture of xylan and glucose was used as a carbon source, we could observe glucose repression of xylanase (about 70-fold) and ${\beta}$-xylosidase (about 40-fold) syntheses. Whereas, the level of the glucose repression of the expression of the xylA gene encoding the major ${\beta}$-xylosidase of B. stearothermophilus was assessed to be about l0-fold when the relative amounts of the xylA transcript were determined. From the sequence of the xylA gene, we could find two CRE-like sequences (CRE-l: nucleotides ＋124 to ＋136 and CRE-2:＋247 to ＋259) within the reading frame of the xylA gene, either or both of which were suspected to be involved in catabolite repression of the xylA gene.

• KSBB Journal
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• 제10권2호
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• pp.137-142
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• 1995

Sucrose를 탄소원으로 이용할 수 있는 대장균 W 를 A. eutrophus PHA 합성 유전자가 cloning된 높 은 복제수의 plasmid pSYL105로 형질전환하여 단 순배지에서 배양시 $0.21g/\ell$ 의 낮은 PHB 농도를 얻었다. 이에 107}지의 복합질소원을 소량 첨가하여 PHB 합성에 미치는 영향을 살펴 보았다. Tryptone, casamino acids, casein hydrolysate, 혹은 soy bean hydrolysate의 첨가시 PHB 합성 이 10배 이 상 증대되었다. 또한 이때 sucrose로부터의 PHB 수율도 10배 이상 증가하여 이 네 가지 복합질소원 을 척정 농도로 첨가함으로써 sucrose로부터 효과적인 PHB 생산이 가능함을 알았다.

• 상하수도학회지
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• 제13권2호
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• pp.47-54
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• 1999

SRB(Sulfate Reducing Bacteria) converts sulfate into sulfide using an organic carbon source as the electron donor. The sulfide formed precipitates the various metals present in the AMD (Acid Mine Drainage). This study is the fundamental research on heavy metal removal from AMD using SRB. Two completely mixed anaerobic reactors were operated for cultivation of SRB at the temperature of $30^{\circ}C$ and anaerobic batch reactors were used to evaluate the effects of carbon source, COD/sulfate($SO_4^=$) ratio and alkalinity on sulfate reduction rate and heavy metal removal efficiency. AMD used in this study was characterized by low pH 3.0 and 1000mg/l of sulfate and dissolved high concentration of heavy metals such as iron, cadmium, copper, zinc and lead. It was found that glucose was an organic carbon source better than acetate as the electron donor of SRB for sulfate reduction in AMD. Amount of sulfate reduction maximized at the COD(glucose)/sulfate ratio of 0.5 in the influent and then removal efficiencies of heavy metals were 97.5% of Cu, 100% of Pb, 100% of Cr, 49% of Mn, 98% of Zn, 100% Cd and 92.4% of Fe. Although sulfate reduction results in an increase in the alkalinity of the reactor, alkalinity of 1000mg/1 (as $CaCo_3$) should be should be added continuously to the anaerobic reactor in order to remove heavy metals from AMD.

• Journal of Microbiology and Biotechnology
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• 제22권3호
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• pp.371-377
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• 2012

The present study describes medium-chain-length polyhydroxyalkanoates (mcl-PHAs) production by the Pseudomonas Gl01 strain isolated from mixed microbial communities utilized for PHAs synthesis. A two-step fed-batch fermentation was conducted with glucose and waste rapeseed oil as the main carbon source for obtaining cell growth and mcl-PHAs accumulation, respectively. The results show that the Pseudomonas Gl01 strain is capable of growing and accumulating mcl-PHAs using a waste oily carbon source. The biomass value reached 3.0 g/l of CDW with 20% of PHAs content within 48 h of cultivation. The polymer was purified from lyophilized cells and analyzed by gas chromatography (GC). The results revealed that the monomeric composition of the obtained polyesters depended on the available substrate. When glucose was used in the growth phase, 3-hydroxyundecanoate and 3-hydroxydodecanoate were found in the polymer composition, whereas in the PHAs-accumulating stage, the Pseudomonas Gl01 strain synthesized mcl-PHAs consisting mainly of 3-hydroxyoctanoate and 3-hydroxydecanoate. The transcriptional analysis using reverse-transcription real-time PCR reaction revealed that the phaC1 gene could be transcribed simultaneously to the phaZ gene.

• 한국식품영양과학회지
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• 제19권6호
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• pp.641-645
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• 1990

In order to study the influence of culture conditions on cell growth and lipid formation by Mucor sp, various carbon and nitrogen sources initial pH and C./N ratio of medium were investigated. Glucose was found to be suitable carbon source in terms of lipid yield and ${\gamma}$-linolenic acid(GLA) content. When NH4Cl and (NH4)2SO4 were used as nitrogen source lipid content was high(19-21%) but GLA content was low(15-17%) On the other hand when NaNO3 and KNO3 were used lipid content was low(about 13%) but GLA content was high(22-23%). The highest production of lipid was obtained at a C/N ratio of 40 using glucose and (NH4)2SO4 as carbon and nitrogen source respectively. it was found that lipid yield was high at pH4.6 Also this fungus did not grow at 35$^{\circ}C$ and lipid yield was highr at 15$^{\circ}C$ than $25^{\circ}C$.

• 한국균학회지
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• 제19권1호
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• pp.41-46
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• 1991

화학공장폐수가 유입되는 곳의 자연수에서 프탈산화합물을 탄소원으로 이용하여 성장하는 효모 3종을 분리하였는데, 형태학적 및 생화학적 특성의 연구결과 이들은 Candide sp., Rhodotorula sp., To-rulopsis sp. 로 동정되었다. 분리한 효모들은 프탈산화합물 뿐만 아니라 톨류엔 등 다수의 방향족화합물을 이용하여 성장하기에 화학공업의 발달로 인하여, 자연생태에 다량 유입, 축적되고 있는 난분해성 방향족화합물의 효율적 생분해 방법을 모색하는에 활용될 수 있으리라 추정되며, 따라서 이들 효모에 대한 다각적 연구가 필요하다고 사료된다.

• Journal of Microbiology and Biotechnology
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• 제16권4호
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• pp.543-549
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• 2006

DNA microarray was used to study the transcription profiling of Escherichia coli adapting to acetate as a sole carbon source. Bacteria grown in glucose minimal media were used as a reference. The dynamic expression levels of 3,497 genes were monitored at seven time points during this adaptation. Among the central metabolic genes, the glycolytic and glucose phosphotransferase genes were repressed as the bacteria entered stationary phase, whereas the glyoxylate pathway, TCA cycle, and gluconeogenic genes were induced. Distinct induction or repression patterns were recognized among different pathway genes. For example, the repression of glycolytic genes and the induction of gluconeogenic ones started immediately after glucose was depleted. On the other hand, the regulation of the pentose phosphate pathway genes and glyoxylate genes gradually responded to the glucose depletion or was more related to growth in acetate. When the whole genome was considered, many of the CRP, FadR, and Cra regulons were immediately responsive to the glucose depletion, whereas the $\sigma^s$, Lrp, and IHF regulons were gradually responsive to the glucose depletion. The expression profiling also provided differential regulations between isoenzymes; for example, malic enzymes A (sfcA) and B (maeB). The expression profiles of three genes were confirmed with RT-PCR.