• Journal of Microbiology and Biotechnology
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• v.14 no.5
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• pp.967-971
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• 2004

The kinetics of sulfite uptake were examined in a wild-type laboratory strain of Saccharomyces cerevisiae to determine if carrier-mediated sulfite uptake involved a proton symport, as previous studies on sulfite uptake have suggested both an active process and facilitated diffusion. Accumulation of intracellular sulfite was initially rapid and linear up to 50 sec. Uptake was saturable at final concentrations equal to or greater than 3 mM sulfite, and increased 2-fold in the presence of 2% glucose. Uptake was significantly reduced in cells pretreated with 100-500 $\mu$M carbonyl cyanide mchlorophenylhydrazone (CCCP) or 2,4-dinitrophenol (DNP), both of which dissipate proton gradients. Uptake was also significantly inhibited in the presence of 1 mM arsenate, an inhibitor of ATP synthesis. Extracellular alkalization was observed in cells incubated with 1-2 mM sulfite in a weak tartrate buffer at pH 3.5 and 4.5. These findings suggest that the bisulfite ion, $HSO_3^-$, an anionic form of sulfite, is taken up by a carrier-mediated proton symport. A met16 sull sul2 mutant, impaired in both sulfite formation and sulfate uptake, was found able to grow on a medium with sulfite as the sole Sulfur source, indicating that the sulfate transporters Sul1p and Sul2p are not required for sulfite uptake.

• Journal of Microbiology and Biotechnology
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• v.28 no.5
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• pp.816-820
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• 2018

The stringent response (SR), which is activated by accumulation of (p)ppGpp under conditions of growth-inhibiting stresses, plays an important role on growth and virulence in Vibrio cholerae. Herein, we carried out a genome-wide screen using transposon random mutagenesis to identify genes controlled by SR in a (p)ppGpp-overproducing mutant strain. One of the identified SR target genes was flaC encoding flagellin. Genetic studies using flaC and SR mutants demonstrated that FlaC was involved in bacterial growth, toxin production, and normal flagellum function under conditions of high (p)ppGpp levels, suggesting FlaC plays an important role in SR-induced pathogenicity in V. cholerae.

• Journal of Microbiology and Biotechnology
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• v.25 no.6
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• pp.880-886
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• 2015

Bacterial heme was produced from a genetic-engineered Escherichia coli via the porphyrin pathway and it was useful as an iron resource for animal feed. The amount of the E. coli-synthesized heme, however, was only few milligrams in a culture broth and it was not enough for industrial applications. To analyze heme biosynthetic pathways, an engineered E. coli artificially overexpressing ALA synthase (hemA from Rhodobacter sphaeroides) and pantothenate kinase (coaA gene from self geneome) was constructed as a bacterial heme-producing strain, and both the transcription levels of pathway genes and the intermediates concentrations were determined from batch and continuous cultures. Transcription levels of the pathway genes were not significantly changed among the tested conditions. Intracellular intermediate concentrations indicated that aminolevulinic acid (ALA) and coenzyme A (CoA) were enhanced by the hemA-coaA co-expression. Intracellular coproporphyrinogen I and protoporphyrin IX accumulation suggested that the bottleneck steps in the heme biosynthetic pathway could be the spontaneous conversion of HMB to coproporphyrinogen I and the limited conversion of protoporphyrin IX to heme, respectively. A strategy to increase the conversion of ALA to heme is discussed based on the results.

• Journal of Microbiology and Biotechnology
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• v.12 no.1
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• pp.31-38
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• 2002

Bacteria have evolved various types of resistance mechanism to toxic heavy metals, such as arsenic and antimony. An arsenical and antimonial resistant bacterium was isolated from a shallow creek draining a coal-mining area near Taebaek City, in Kangwon-Do, Korea. The isolated bacterium was identified and named as Pseudomonas sp. KM20 after biochemical and physiological studies were conducted. A plasmid was identified and its function was studied. Original cells harboring the plasmid were able to grow in the presence of 15 mM sodium arsenite, while the plasmid-cured (plasmidless) strain was sensitive to as little as 0.5 mM sodium arsenate. These results indicated that the plasmid of Pseudomonas sp. KM20 does indeed encode the arsenic resistance determinant. In growth experiments, prior exposure to 0.1 mM arsenate allowed immediate growth when they were challenged with 5 mM arsenate, 5 mM arsenite, or 0.1 mM antimonite. These results suggested that the arsenate, arsenite, and antimonite resistance determinants of Pseudomonas sp. KM20 plasmid were indeed inducible. When induced, plasmid-bearing resistance cells showed a decreased accumulation $of\;73^As$ and showed an enhanced efflux $of\;^73As$. These results suggested that plasmid encoded a transport system that extruded the toxic metalloids, resulting in the lowering of the intracellular concentration of toxic oxyanion. In a Southern blot study, hybridization with an E. coli R773 arsA-specific probe strongly suggested the absence of an arsA cistron in the plasmid-associated arsenical and antimonial resistance determinant of Pseudomonas sp. KM20.

• Fisheries and Aquatic Sciences
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• v.6 no.4
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• pp.194-202
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• 2003

Budgets for water, nitrogen, and chemical oxygen demand (COD) were determined in two 0.012 ha earthy-bottom ponds stocked with Israeli strain common carp at an initial stocking density of $20\;fish/m^3$. Total ammonia nitrogen (TAN) concentrations increased continuously but later decreased in pond A as a consequence of high nitrification. COD concentrations increased during the experimental period due to the accumulation of feed input. Nutrient budgets showed that feed represented $94-95\%$ of nitrogen input and about 99% of organic matter input. Fish harvest accounted for $40\%$ of nitrogen and organic matter input. Seepage and water exchange removed $15-17\%$ of nitrogen input but only $1-2\%$ of organic matter. Draining of the ponds removed $20-26\%$ of input nitrogen, mostly in inorganic forms, but removed only minus organic matter. Fish and water column respiration accounted for $39\%$ of organic matter input, and benthic respiration accounted for $7-12\%$ of organic matter input. No significant change of nitrogen and organic matter in both pond bottoms were found during the three-month growth period. The unrecovered input nitrogen, about $6.3-13\%$, was lost through denitrification and ammonia volatilization. On a dry matter basis, fish growth removed $31\%$ of total feed input and left $69\%$ as metabolic wastes.

• KSBB Journal
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• v.27 no.3
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• pp.172-176
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• 2012

In this study, microalgae Arthrospira platensis (A. platensis) mutants induced by ethyl methane sulfonate (EMS) and further selection for resistance of cerulenin, a potent inhibitor of fatty acid synthase, were characterized. The mutants selected by $2{\mu}M$, $5{\mu}M$ and $10{\mu}M$ of cerulenin were designated EC2, EC5 and EC10, respectively. Under normal growth conditions, the mutants and parental strain exhibited similar growth pattern. The mutants of A. platensis showed enhanced lipid accumulation and phycobiliproteins (phycoerythrin, phycocyanin). The lipid content of mutants EC2 and EC5 was about 4.4 and 4.8-fold higher than wild type. The phycoerythrin and phycocyanin content of mutants EC2 and EC5 was increased about 1.5 and 6.9-fold and 1.4 and 3.8-fold, respectively, compared to the wild type. The chlorophyll and carotenoid content of mutants was slightly increased. The high lipid and pigment contents exhibited by A. platensis mutants would make an excellent candidate for the production of commercially interesting biologically active compounds.

• Journal of Marine Bioscience and Biotechnology
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• v.2 no.1
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• pp.60-67
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• 2007

For the first time in Vietnam, morphological and molecular studies of a species belonging to Bacillariophyceae collected in Northern coast of Vietnam are presented. Observations with microscope showed that this species belong to genus: Pseudo-nitzschia and seem like P. pungens. Sequence data from the partial 18S small subunit ribosomal RNA gene (18S rDNA) and the internal transcribed spacer 1 - 5.8S - internal transcribed 2 have been used to determine clearly and generate a phylogenetic framework of the obtained sequences to previously reported sequences in GenBank. These results allowed us to highlight described species of Bacillariophyceae in Northern coast of Vietnam. Furthermore, accumulation of molecular study would be helpful for the identification of scientific name of harmful algal species and further taxonomic studies in Vietnam.

• Journal of the Society of Naval Architects of Korea
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• v.45 no.5
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• pp.538-546
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• 2008

In this paper, the constitutive equation is developed to analyze the characteristics of strain-induced plasticity in the range of low temperature of 316 stainless steel. The practical usefulness of the developed equations is evaluated by the comparison between experimental and numerical results. For 316 stainless steel, constitutive equations, which represent the characteristics of nonlinear material behavior under the cryogenic temperature environment, are developed using the Bodner's plasticity model. In order to predict the material behaviour such as damage accumulation, Bodner-Chan's damage model is implemented to the developed constitutive equations. Based on the developed constitutive equations, 3-D finite element analysis program is developed, and verified using experimental results.

• Proceedings of the Korean Society of Plant Biotechnology Conference
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• 2005.11a
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• pp.361-366
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• 2005

Opium poppy (Papaver somniferum L.) is one of the most important medicinal plants, which is used as a sole commercial source of narcotic analgesic, morphine. The transformant of opium poppy we have established by infection of Rhizobium rhizogenes (formerly Agrobacterium rhizogenes) strain MAFF03-01724 showed aberrant morphology and altered opium alkaloid composition. The major alkaloid produced by this transformant was thebaine (16.3%, opium dry weight) instead of morphine. It is likely that this 'thebaine poppy' phenotype was caused by the integration of T-DNA(s) into the poppy genome DNA, and their inserted loci are of great interest. To gain an insight into the mechanism of nonnarcotic thebaine accumulation for the further approach toward the creation of 'codeine poppy' which produces codeine as a major alkaloid, the genetical and morphological analyses on the transformant was carried out. Here we report the results of the detailed analysis on the T-DNA inserted loci of T0 transfromant and the correlation between opium alkaloid composition and segregated T-DNA integration pattern in the self-pollinated T1 transformants.

• ALGAE
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• v.32 no.3
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• pp.245-259
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• 2017

We report on the culture growth and stress-induced secondary carotenogenesis in a biotechnologically promising but largely unexplored chlorophyte Coelastrella rubescens strain Vinatzer/Innsbruck V 195. Changes in the cell morphometry, biomass accumulation, its carotenoid and fatty acid profiles were followed in the cultures supplemented with either inorganic ($CO_2$) or organic (sodium acetate) carbon on the background of low-pH stress. Collectively, the results of the study characterize C. rubescens as a biotechnologically promising, potentially double-purpose organism. It produces several secondary keto-carotenoids with a considerable proportion of astaxanthin and canthaxanthin. At the same time, the cell lipid fatty acid profile of this microalga is suitable for obtaining a high-quality biodiesel complying with the strictest EN14214 European standard.