• 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 $C_i{\geq}1.0mgC/L$.

• Journal of Plant Biology
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• v.38 no.1
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• pp.87-93
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• 1995

For understanding physiological nature of phototaxis in Synechocystis sp. PCC 6803 PTX(S. 6803 PTX), we examined the effects of some metabolic inhibitors and cation ionophore on the phototactic movement. In the presence of DCMU, which blocks the photosynthetic electron transport just after photosystem II acceptor, there was no inhibitory effect on the phototaxis up to $100\;\mu\textrm{M}$. Instead, the respiratory electron chain inhibitor such as sodium azide dramatically impaired the phototaxis in S. 6803 PTX. These observations indicate that the phototaxis is linked not to photo-phosphorylation, but to respiratory phosphorylation. When the cells were treated with un couplers such as CCCP or DNP, which dissipate the electrochemical gradient of proton($\Delta\mu_{H}+$) across the cytoplasmic membrane, these chemicals did not affect phototaxis. In contrast, when cells were treated with DCCD or NBD which deprive cells of A TP but leave $\Delta\mu_{H}+$ intact across the membrane, the phototactic movement was severly reduced. These results imply that ATP production, not proton motive force, is involved in the phototactic movement in this organism as a driving motive force. The application of specific calcium ionophore A23187 strongly impaired positive phototaxis. Calcium fluxes should be engaged in the sensory trans-duction of phototactic orientation. Finally, when ethionine was supplimented to culture media, the photomovement of this organism was inhibited. This implies that methylation/demethylation mechanism controls the process of phototaxis in S. 6803 PTX like chemotaxis in E. coli and Salmonella typhimurium.murium.

• Proceedings of the Korean Society of Potoscience Conference
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• spring
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• pp.108-108
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• 1999

• Proceedings of the Korean Society of Potoscience Conference
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• spring
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• pp.73-76
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• 2003

• Proceedings of the Korea Society of Environmental Biology Conference
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• 2005.12a
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• pp.94-94
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• 2005

• Journal of Microbiology and Biotechnology
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• v.22 no.2
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• pp.166-169
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• 2012

In several biotechnological applications of living bacterial cells with inducible gene expression systems, the extent of overexpression and the specificity to the inducer are key elements. In the present study, we established the concentration ranges of $Zn^{2+}$, $Ni^{2+}$, $Co^{2+}$, ${AsO_2}^-$, and $Cd^{2+}$ ions that caused significant activation of the respective promoters of Synechocystis sp. without concomitant unspecific stress responses. The low expression levels can be increased up to 10-100-fold upon treatments with $Cd^{2+}$, ${AsO_2}^-$, $Zn^{2+}$, and $Co^{2+}$ ions and up to 800-fold upon $Ni^{2+}$ treatment. These results facilitate the development of conditional gene expression systems in cyanobacteria.

• Rapid Communication in Photoscience
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• v.1 no.1
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• pp.21-24
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• 2012

Influence of gamma rays on the cyanobacterium Synechocystis sp. PCC 6803 cells was investigated in terms of a bidirectional hydrogenase, which is encoded by hoxEFUYH genes and responsible for biohydrogen production. Irradiated cells revealed a substantial change in stoichiometry of photosystems at one day after gamma irradiation at different doses. However, as evaluated by the maximal rate of photosynthetic oxygen evolution, maximal photochemical efficiency of photosystem II, and chlorophyll content, net photosynthesis or photosynthetic capacity was not significantly different between the control and irradiated cells. Instead, transcription of hoxE, hoxH, or lexA, which encodes a subunit of bidirectional hydrogenase or the only transcriptional activator, LexA, for hox genes, was commonly enhanced in the irradiated cells. This transcriptional enhancement was more conspicuously observed immediately after gamma irradiation. In contrast, hydrogenase activities were found to somewhat lower in the irradiated cells. Therefore, we propose that transcription of hox genes should be enhanced by gamma irradiation in a LexA-mediated and possibly photosynthesis-independent manner and that this enhancement might not induce a subsequent increase in hydrogenase activities, probably due to the presence of post-transcriptional and/or post-translational regulatory mechanisms.

• The Journal of Natural Sciences
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• v.19 no.1
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• pp.27-35
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• 2008

The importance of microbial activity in the alteration and deterioration of stone and concrete walls has been frequently neglected. Organisms present on stone monuments can include photolithoautotrophs, such as algae, cyanobacteria, mosses, and higher plants. Because of their ability to survive repeated drying and rehydration cycles and high UV levels, the cyanobacteria are particularly important on exposed surfaces. The cyanobactria distributed on the surface of the stone cultural heritages in Gwanschoksa, Nonsan city were investigated. Chlorococcus sp. Aanabaena sp. Gloeocapsa sp Lyngbya sp. Stigomena sp. Synechocystis sp were identified. Haplaosiphon fontinalis and Stigonema turfaceum, which were not recoded is Korea, were also identified. Cells often have thick pigmented sheath in dry, sun-exposed environment and shorter filament, which can be different than that in aquatic systems. Special attention should be paid to production of an adequate DNA database in order to accelerate the rate at which information on the species present in biofilms become available.

• Journal of Microbiology and Biotechnology
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• v.18 no.8
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• pp.1386-1392
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• 2008

A gene (sll0158) putatively encoding a glycogen branching enzyme (GBE, E.C. 2.4.1.18) was cloned from Synechocystis sp. PCC6803, and the recombinant protein expressed and characterized. The PCR-amplified putative GBE gene was ligated into a pET-21a plasmid vector harboring a T7 promoter, and the recombinant DNA transformed into a host cell, E. coli BL21(DE3). The IPTG-induced enzymes were then extracted and purified using Ni-NTA affinity chromatography. The putative GBE gene was found to be composed of 2,310 nucleotides and encoded 770 amino acids, corresponding to approx. 90.7 kDa, as confirmed by SDS-PAGE and MALDI-TOF-MS analyses. The optimal conditions for GBE activity were investigated by measuring the absorbance change in iodine affinity, and shown to be pH 8.0 and $30^{\circ}C$ in a 50 mM glycine-NaOH buffer. The action pattern of the GBE on amylose, an $\alpha$-(1,4)-linked linear glucan, was analyzed using high-performance anion-exchange chromatography (HPAEC) after isoamylolysis. As a result, the GBE displayed $\alpha$-glucosyl transferring activity by cleaving the $\alpha$-(1,4)-linkages and transferring the cleaved maltoglycosyl moiety to form new $\alpha$-(1,6)-branch linkages. A time-course study of the GBE reaction was carried out with biosynthetic amylose (BSAM; $M_p{\cong}$8,000), and the changes in the branch-chain length distribution were evaluated. When increasing the reaction time up to 48 h, the weight- and number-average DP ($DP_w$ and $DP_n$) decreased from 19.6 to 8.7 and from 17.6 to 7.8, respectively. The molecular size ($M_p$, peak $M_w{\cong}2.45-2.75{\times}10^5$) of the GBE-reacted product from BSAM reached the size of amylose (AM) in botanical starch, yet the product was highly soluble and stable in water, unlike AM molecules. Thus, GBE-generated products can provide new food and non-food applications, owing to their unique physical properties.

• 한국약용작물학회:학술대회논문집
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• 2008.11a
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• pp.487-488
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• 2008