• BMB Reports
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• v.39 no.4
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• pp.394-399
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• 2006

The transport of putrescine into a moderately salt tolerant cyanobacterium Synechocystis sp. PCC 6803 was characterized by measuring the uptake of radioactively-labeled putrescine. Putrescine transport showed saturation kinetics with an apparent $K_m$ of $92{\pm}10\;{\mu}M$ and $V_{max}$ of $0.33{\pm}0.05\;nmol/min/mg$ protein. The transport of putrescine was pH-dependent with highest activity at pH 7.0. Strong inhibition of putrescine transport was caused by spermine and spermidine whereas only slight inhibition was observed by the addition of various amino acids. These results suggest that the transport system in Synechocystis sp. PCC 6803 is highly specific for polyamines. Putrescine transport is energy-dependent as evidenced by the inhibition by various metabolic inhibitors and ionophores. Slow growth was observed in cells grown under salt stress. Addition of low concentration of putrescine could restore growth almost to the level observed in the absence of salt stress. Upshift of the external osmolality generated by either NaCl or sorbitol caused an increased putrescine transport with an optimum 2-fold increase at 20 mosmol/kg. The stimulation of putrescine transport mediated by osmotic upshift was abolished in chloramphenicol-treated cells, suggesting possible involvement of an inducible transport system.

• Transactions of the Korean hydrogen and new energy society
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• v.19 no.6
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• pp.529-536
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• 2008

Cyanobacteria Synechocystis PCC 6803 or the extracted thylakoid membrane from this strain was appled to photosynthetic bio-electrochemical fuel cell(PBEFC) for the production of hydrogen under the illumination of 48Klux using halogen lamp. PBEFC was composed of anode, cathode and membrane between them. Electrode material was carbon paper while electron mediator and receptor were added phenazine methosulfate(PMS) and potassium ferricyanide respectively. When water and 50 mM tricine buffer and $300{\mu}M$ PMS were added to the anode under the light condition, PBEFC produced the current density $4.4{\times}10^{-5}\;mA/cm^2$, $1.4{\times}10^{-4}\;mA/cm^2$ and $2.4{\times}10^{-4}\;mA/cm^2$, respectively. And the addition of the thylakoid membrane to the system increased current density to $1.3{\times}10^{-3}\;mA/cm^2$. Two times increase of the thylakoid membrane into the anode doubled the current density to $2.6{\times}10^{-3}\;mA/cm^2$. But the current density was not increased proportionally to the amount of thylakoid membrane increased. The system was unstable to measure the electricity output due to the foam production in the anode. Addition of triton X-100 and tween 80 stabilized the system to measure the electricity output but the current density was not increased higher than $8.4{\times}10^{-4}\;mA/cm^2$ and $2.3{\times}10^{-3}\;mA/cm^2$. When the thylakoid membrane was substituted to Synechocystis PCC 6803 cells of four-day culture which has chlorophyll contents $20.5{\mu}g/m{\ell}$, maximum current density was $1.3{\times}10^{-3}\;mA/cm^2$ with $1\;k{\Omega}$ resistance.

• KSBB Journal
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• v.13 no.1
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• pp.101-107
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• 1998

Carbon dioxide is estimated to be responsible for 60% of the global warming effect, and this percentage is tending upward. Studies on removal and fixation of $CO_2$ in the flue gas are recognized as one of the important roles of the future biotechnology. Photobiological systems have considerably higher photosynthetic efficiency than conventional biomass system. The experiment for the photosynthetic fixation of $CO_2$ and the biomass production was performed with various initial cell concentration in a tubular photobioreactor and a bubble column $CO_2$ contactor with a gas sparger of $CO_2$ -enriched air(0.03~20%). Synechocystis PCC 6803 could grow at 10~20% $CO_2$ content under pH control. The highest specific growth rate, 0.0258 $h^{-1}$ , was obtained at 5% $CO_2$-air mixture. The maximum cell production rate, 0.2784 g/L.day, was obtained when the initial cell concentration was 0.45 g/L at 5% $CO_2$ -air mixture. The maximum cell concentration was 2.03 g/L in the tubular photobioreactor when the light intensity was $45.5{\mu}$ $E/m^2$ . s. This system showed 0.482 g $CO_2$ /L . day of the $CO_2$ fixation.

• Korean journal of applied entomology
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• v.43 no.1
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• pp.35-41
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• 2004

Bacillus thuringiensis produces crystal proteins toxic to medically and agriculturally important pests during sporulation. To improve the activity of insecticidal crystal protein in applying to mosquito larval control, an expression vector, pSyn4D harboring the mosquitocidal cry11Aa gene under control of psbA promoter of Amaranthus hybridus was constructed. This expression vector was transformed into Synechocystis PCC6803 and a transformant, Tr2C was selected with kanamycin. The mosquitocidal cry11Aa gene was stably integrated Into genomic DNA of Tr2C in PCR detection using cry11Aa-specific primers. The transformant expressed 72-kDa Cry11Aa protein and median lethal time (LT$\sub$50/) was approximately 2.1 days for Culex tritaeniorhynchus larvae and 0.7 day for Anopheles sinensis larvae, respectively. These results suggest this transformant can be used for mosquito larval control as a biological control agent.

• Journal of Photoscience
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• v.11 no.3
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• pp.89-94
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• 2004

Motile cyanobacterium Synechocystis sp. PCC 6803 cells show photomovement with respect to the light stimulus. Under lateral irradiation, Synechocystis displays a phototactic gliding movement toward the light source by a twodimensional random biased walk. Under vertical irradiation, Synechocystis decreased the frequency of mean vectorial gliding speed dependent on the applied fluence rate, whereas the deviation distribution width of the speed increased. This strongly suggests the involvement of photokinesis. Evidence for the cyanobacterial photokinesis was discussed in the previous report (Choi et al., 1999. Photochem. Photobiol. 70, 95-102) demonstrating that the gross scalar speed of vertically irradiating cells increased by about 50% compared with that of dark-adapted cells. In the visible wavelength range, Synechocystis cells showed a maximal photokinetic activity at 420 nm and a second maximal activity at 680 nm. The threshold action spectrum for the photokinesis resembles the absorption spectrum of chlorophyll with major differences in the phototaxis action spectrum at 560 nm and 660 nm. We postulate that the cyanobacterial photokinesis is powered by the energy-generating chlorophyll pigments.

• Environmental Engineering Research
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• v.20 no.4
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• pp.347-355
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• 2015

The growth kinetics of phototrophic microorganisms can be controlled by the light irradiance, the concentration of an inorganic nutrient, or both. A multi-component kinetic model is proposed and tested in novel batch experiments that allow the kinetic parameters for each factor to be estimated independently. For the cyanobacterium Synechocystis sp. PCC6803, the estimated parameters are maximum specific growth rate $({\mu}_{max})=2.8/d$, half-maximum-rate light irradiance $(K_L)=11W/m^2$, half-inhibition-rate light irradiance $(K_{L,I})=39W/m^2$, and half-maximum-rate concentration for inorganic carbon $(K_{S,Ci})=0.5mgC/L$, half-maximum-rate concentration for inorganic nitrogen $(K_{S,Ni})=1.4mgN/L$, and half-maximum-rate concentration for inorganic phosphorus $(K_{S,Pi})=0.06mgP/L$. Compared to other phototrophs having ${\mu}max$ estimates, PCC6803 is a fast-growing r-strategist relying on reaction rate. Its half-maximum-rate and half-inhibition rate values identify the ranges of light irradiance and nutrient concentrations that PCC6803 needs to achieve a high specific growth rate to be a sustainable bioenergy source. To gain the advantages of its high maximum specific growth rate, PCC6803 needs to have moderate light illumination ($7-62W/m^2$ for ${\mu}_{syn}{\geq}1/d$) and relatively high nutrient concentrations: $N_i{\geq}2.3 mgN/L$, $P_i{\geq}0.1mgP/L$, and $C_i{\geq}1.0mgC/L$.

• Microbiology and Biotechnology Letters
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• v.31 no.2
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• pp.103-110
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• 2003

The regulation of pyrimidine nucleotide synthesis has been proved to be controlled by a regulatory protein PyrR-mediated attenuation in the Gram-positive bacteria. After several bacterial genome sequencing projects, we have discovered the PyrR orthologues in the databases for Haemophilus influenzae and Synechocystis and sp. PCC6803 genome sequences. To investigate whether these PyrR orthologue proteins regulate pyrimidine nucleotide synthesis as well as the cases of Bacillus, the PyrR regions of each strains were amplified by PCR and cloned with pUC19 or T-vector in Escherichia coli and with a shuttle vector pHPS9 for E. coli and B. subtilis. For the regulation test of the PyrR orthologues, the aspartate-transcarbamylase (ATCase) assay was carried out. From the results of the ATCase assay, it was confirmed that Synechocystis sp. PCC6803 could not restore by pyrimidines to a B. subtilis, PyrR but H. influenzae PyrR could. For Purification of PyrR orthologue proteins, PyrR orthologue genes were cloned into the expression vector (pET14b). Over-expressed product of PyrR orthologue genes was purified and analyzed by the SDS-PACE. The purified PyrR orthologue proteins from H. influenzae and Synechocystis sp. PCC6803 turned out to be molecular mass of 18 kDa and 21 kDa, respectively. The result of uracil phosphoribosyl transferase (UPRTase) assay with purified PyrR orthologue proteins showed that H. influenzae PyrR protein only has UPRTase activity. In addition, we could predict several regulatory mechanisms that PyrR orthologue proteins regulate pyrimidine de novo synthesis in bacteria, through phylogenetic analysis for PyrR orthologue protein sequences.

• Proceedings of the Microbiological Society of Korea Conference
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• 2002.10a
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• pp.203-205
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• 2002

Light is an environmental signal that regulates photomovement and main energy source of photosynthesis in the cyanobacterium Synechocystis sp. PCC 6803 (Syn6803). Syn6803 is a popular model system for study of plant functional genomics. In this report, we adopted 2D gel based proteomics study to investigate proteins related with the light absorption and photo-protection in Syn6803. More than 700 proteins were detected on the SDS-gels stained with silver nitrate. Several proteins showing different expression level under various light conditions were identified with MALDI-TOF Mass spectrometry. As a comparison, we also conducted ICAT-based proteome study using WT and cphl (cyanobacterial phytochrome 1) mutant. A cphl deletion led to changes in the expression of proteins involved in translation, photosynthesis including photosystem and CO2 fixation, and cellular regulation. We are currently involved in TAP-tagging method to study protein-protein interactions in search for the molecular component involved in the light signal transduction of Syn6803 photomovement.

• Journal of Microbiology and Biotechnology
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• v.18 no.6
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• pp.1090-1094
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• 2008

In this article, we show that the orf slr1471 from Synechocystis sp. PCC 6803 codes for a functional member of the YidC/Alb3/Oxa1 protein family, and the encoded protein has a transmembrane topology with a common core structure. Using specific antibodies raised against the Synechocystis YidC homologous protein, we further show that the Synechocystis YidC protein appears to be predominantly localized in the cyanobacterial cytoplasmic membrane. The impact of the described findings for synthesis of membrane proteins and for protein sorting within cyanobacterial cells is discussed.

• Microbiology and Biotechnology Letters
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• v.24 no.2
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• pp.173-177
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• 1996

Bacillus thuringiensis subsp. morrisoni PG-14 is a gram-positive soil bacterium producing mosquitocidal parasporal inclusions composed of several crystal proteins. Among these crystal protein genes, cryIVD gene is one of major component which has 72 kDa in size. However, these parasporal inclusions sink quickly from the surface of water where mosquito larval feeding occurred. To develope mosquitocidal cyanobacterium, therefore, we constructed the expression vector, pCYASK 5-1 harboring cryIVD gene. The expression vector, pCYASK5-1 was transformed into the cyanobacterium Syne- chocystis PCC6803 reported as a natural mosquito larval food source and the transformants were selected with kanamycin. Expression of IVD gene in transformant was characterized by SDS-polyacrylamide gel electrophoresis (PAGE) and immunoblot analysis. The mosquitocidal activity of a transformant was determined with Culex tritaeniorhynchus. The results showed that, the transformed cyanobacterium is toxic to mosquito larvae and will be expected as a potential agent that is used for mosquito control.