• Journal of Microbiology and Biotechnology
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• v.14 no.4
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• pp.653-657
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• 2004

The cold resistant mutants of P. fluorescens strain $PRS_{9}$ and ATCC13525 were developed which could grow equally well at $28^{\circ}C$ and $10^{\circ}C$. All the mutants were tested for siderophore production, of which $CRPF_9$ (ATCC13525 mutant) was selected, as there was a 16.8-fold increase when compared to its wild-type. Under in vitro conditions, $CRPF_9$ showed better growth promotion both in wheat (29.1% increase in root length) and mung bean (51.5% increase in root length) at $10^{\circ}C$. Greenhouse trials showed a significant increase in root (13.84cm) and shoot (15.0cm) length of $CRPF_9$-treated mung bean seeds, indicating increased rhizocompetence of the mutant. Ferric citrate was a better iron source than ferric hydroxide for plant growth.

• Journal of Microbiology and Biotechnology
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• v.11 no.3
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• pp.384-388
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• 2001

The metabolic pathway synthesis algorithm was applied to estimate the maximum ethanol yield from xylose in a model recombinant Saccharomyces cerevisiae strain containing the genes involved in xylose metabolism. The stoichiometrically independent pathways were identified by constructing a biochemical reaction network for conversion of xylose to ethanol in the recombinant S. cerevisiae. Two independent pathways were obtained in xylose-assimilating recombinant S. cerevisiae as opposed to six independent pathways for conversion of glucose to ethanol. The maximum ethanol yield from xylose was estimated to be 0.46 g/g, which was lower than the known value of 0.51 g/g for glucose-fermenting and wild-type xylose-fermenting yeasts.

• Journal of Microbiology and Biotechnology
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• v.16 no.9
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• pp.1448-1452
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• 2006

The effects of amplifying the gluconeogenic phosphoenolpyruvate carboxykinase of Escherichia coli ($pck_{Ec}$) on succinic acid production in E. coli were examined under anaerobic condition. No significant increase in succinic acid production was observed in E. coli overexpressing the $pck_{Ec}$ gene without supplementing $NaHCO_{3}$ or $MgCO_{3}$. On the other hand, succinic acid production was enhanced as the $NaHCO_{3}$ concentration was increased. When 20 g/l of $NaHCO_{3}$ was added, succinic acid production in recombinant E. coli overexpressing PCK was 2.2-fold higher than that observed in the wild-type strain. It was concluded that the gluconeogenic $pck_{Ec}$ overexpression enabled E. coli to enhance succinic acid production only under the high bicarbonate supplementation condition.

• Proceedings of the Korean Biophysical Society Conference
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• 2002.06b
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• pp.55-55
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• 2002

An alternative sigma factor as encoded by the $\sigma$$\^$B/ gene in Streptomyces coelicolor A3(2) was known to be involved in the differentiation and osmotic stress response. Protein expression profiles of wild-type and a $\sigma$$\^$B/ mutant strain of S coelicolor A3(2), which is impaired in defense against osmotic stress, were compared in the absence and presence of osmotic stress, using 2-dimentional gel electrophoresis.(omitted)

• Archives of Pharmacal Research
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• v.16 no.3
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• pp.231-236
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• 1993

Gly-224 residue of yeast alcohol dehydrogenase was mutated by site-directed mufagenesis to isoleucine, which is the corresponding amino acid residue of horse liver alcohol dehydrogenase. The mutated gene on M13 vector was subcloned in YEp13 and used to transform Saccharomyces cerevisiae 302-21 #2 strain, and the expressed protein was purified. The tumover numbers of mutant enzyme for ethanol and acetaldehyde were decreased copared to wild-type enzyme. The results of product inhibition studies indicated that the reaction mechanism was changed to Iso Theorell-Chance from Ordered Bi Bi. We supposed that Gly-224 was related to the enzyme reaction mechanism.

• KSBB Journal
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• v.24 no.4
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• pp.393-396
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• 2009

New protein secretion system was developed using Type III Secretion System of Salmonella. N-terminal region of SlrP and SptP effector proteins were fused with TliA and EstA-P lipases by overlapping PCR. Lipase activity of Salmonella with SptP-TliA fusion system increased by 2.6 fold compare with wild type Salmonella strain. This result showed that lipase secretion via the T3SS would be a useful protein secretion machinery.

• Korean Journal of Microbiology
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• v.25 no.3
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• pp.184-188
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• 1987

Evidences that the mannose permease of Escherichia coli mediates the infection of N4 in early steps, were obtained as follows. First, A mutant strain of Escherichia coli which was resistant to both wild type N4 and lambda whose genome is Charon 4A containing human genomic fragments in its EcoR I site, could not use mannose efficiently. Second, N4 could not infect pel mutant strains which lack one or all of intact components of mannose permease. However, unknown alterations in N4 made it possible for the phage to infect pel mutant of E. coli. It also turned out to be clear that the receptor of N4 was different from that of lambda.

• Journal of Microbiology
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• v.41 no.1
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• pp.41-45
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• 2003

N crassa mutant strain nap showed reduced growth rate, decreased electric membrane potential, and elevated intracellular ATP content in comparison to the wild type. Blue light induced a hyperpolarization of the membrane potential in both strains. The analysis of oxidative and phosphorylation activities of mitochondria isolated from the two strains has revealed that nap utilized more efficient oxidative pathways. The higher intracellular ATP content in the nap was presumably due to impaired transport systems of the plasma membrane, and to a lesser extent to the functioning of the fully competent respiratory chain. The excess ATP possibly accounts for carotenoid accumulation in the mutant.

• Journal of agriculture & life science
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• v.43 no.6
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• pp.77-84
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• 2009

Using recombinant DNA technology, the vector system containing minimal fragment of a bacterial hemoglobin gene (vgb) was constructed. When this vector was inserted into Escherichia coli, the growth of the host was significantly improved in both viable cell counts and absorbance measurement, compared to that of the wild type strain. In addition, by minimizing the size of bacterial hemoglobin in the vector, the ability of vgb in growth improvement was augmented, due to the reduction of metabolic burden from the maintenance and replication of the plasmid. By using this system, it is expected that the growth of microorganisms can be improved even in the hypoxic condition.

• Proceedings of the PSK Conference
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• 2005.11a
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• pp.231-232
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• 2005

Bacteria of Shigella spp. are responsible for shigellosis in humans, a disease characterized by destruction of the colonic epithelium that is induced by the inflammatory response elicited by invasive bacteria. They use a type III secretion system injecting effector proteins into host cells to induce their entry into epithelial cells and triggers apoptosis in macrophages. We present evidence that the effector OspG is a protein kinase that binds various ubiquitinylated ubiquitin-conjugating enzymes (E2s) and blocks degradation of phospho-$I{\kappa}B{\alpha}$ induced upon entry of bacteria into epithelial cells. Transfection experiments confirmed that OspG interferes with the $NF-{\kappa}B$ activation patway by preventing phospho-$I{\kappa}B{\alpha}$ degradation, suggesting that OspG inactivates a component of the $SCF^{{\beta}-TrCP}$ ubiquitin ligase complex (E3) involved in phospho-$I{\kappa}B{\alpha}$ ubiquitination. Upon infection of ileal loops in rabbits, the ospG mutant induced a stronger inflammatory response compared with the wild-type strain, indicating that OspG down-regulates the host innate response induced by invasive bacteria.