• Journal of Microbiology
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• v.37 no.1
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• pp.1-9
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• 1999

The Biolog redox technology was carried out for evaluation of acidification effect on microbial communities at each stage of pH gradient microcosm. While the number of heterotrophic bacterial population and activities of extracellular enzyme decreased as the pH decreased, the number of total bacteria in the microcosm was not affected. The average color development of sample at each pH-gradient showed a sigmoidal curve, and at higher pH, more overall color development appeared in Biolog plates. Average color development value in Biolog plates was stabilized at 50 hours as an optimum incubation time. The color production in the Biolog plates was caused by cell density at above pH 5.0, but by cell activity below pH 4.0. Principal component analysis of color responses revealed distinctive patterns among the pH-gradient microcosm samples.

• BMB Reports
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• v.38 no.4
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• pp.468-473
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• 2005

The energetics of nitrate uptake by intact cells of the halotolerant cyanobacterium Aphanothece halophytica were investigated. Nitrate uptake was inhibited by various protonophores suggesting the coupling of nitrate uptake to the proton motive force. An artificially-generated pH gradient across the membrane (${\Delta}pH$) caused an increase of nitrate uptake. In contrast, the suppression of ${\Delta}pH$ resulted in a decrease of nitrate uptake. The increase of external pH also resulted in an enhancement of nitrate uptake. The generation of the electrical potential across the membrane ($\Delta\psi$) resulted in no elevation of the rate of nitrate uptake. On the other hand, the valinomycin-mediated dissipation of $\Delta\psi$ caused no depression of the rate of nitrate uptake. Thus, it is unlikely that $\Delta\psi$ participated in the energization of the uptake of nitrate. However, $Na^+$-gradient across the membrane was suggested to play a role in nitrate uptake since monensin which collapses $Na^+$-gradient strongly inhibited nitrate uptake. Exogenously added glucose and lactate stimulated nitrate uptake in the starved cells. N, N'-dicyclohexylcarbodiimide, an inhibitor of ATPase, could also inhibit nitrate uptake suggesting that ATP hydrolysis was required for nitrate uptake. All these results indicate that nitrate uptake in A. halophytica is ATP-dependent, driven by ${\Delta}pH$ and $Na^+$-gradient.

• The Korean Journal of Physiology
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• v.22 no.2
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• pp.281-293
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• 1988

The effect of pH on the rate of PAH uptake was studied in rabbit renal basolateral membrane vesicles (BLMV) and brush border membrane vesicles (BBMV). In the absence of Na in incubation medium, a decrease in external $pH(pH_0)$ led to an increase in probenecid-sensitive PAH uptake by BLMV. In the presence of Na, the probenecid-sensitive PAH uptake was unaltered when the $pH_0$ decreased from 8.0 to 6.0 but further decrease in $pH_0$ to 5.5 increased significantly the uptake. The probenecid-sensitive PAH uptake was not affected by an alteration in pH per se in the absence of a pH gradient with or without the presence of Na. However, the presence of Na stimulated the probenecid-sensitive PAH uptake in all pH ranges tested over that measured in the absence of Na. A similar pattern of pH dependence on the PAH uptake was observed in BBMV but the presence of Na did not alter the probenecid-sensitive PAH uptake in the presence and absence of a pH gradient. Kinetic analysis for BLMV showed that Na or pH gradient increased Vmax of the probenecid-sensitive PAH uptake without a change in Km value. These results suggest that PAH is transported by $OH^-/PAH$ exchange process in the luminal membrane, but the pH dependence in the BLMV is not unequivocally consistent with an anion exchange process. The PAH transport is dependent on Na in BLMV but not in BBMV.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.15 no.2
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• pp.50-62
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• 2009

Purpose: to analyze and compare mucsle activity of Quadriceps femoris depending on the existence of taping while normal people walk forward and backward on treadmill when the slope and speed changes on treadmill. Method: Among 40 people who participated in this study, 20 experimenter who apply a taping walk forward and backward to 0%, 5%, 10% gradient per 2km/h and 4km/h using treadmill to give arbitrary walking behavior, 20 experimenter who doesn't apply a taping also walk forward and backward to 0%, 5%, 10% gradient per 2km/h and 4km/h using treadmill. To analyze muscle activity, We use an electromyography and Kinesio tape of good elasticity for obtained suffient effects in the experiment. Result: During backward walking in 2km/h, Vastus medialis and Vastus lateralis showed significant differences(p<0.05) when apply a taping. During backward walking in 2km/h, Vastus medialis and Rectus femoris, and Vastus lateralis all showed significant differences(p<0.05). During backward walking in 2km/h, Vastus medialis and Vastus lateralis showed significant differences in 10% gradient(p<0.05). During backward walking in 4km/h, Vastus medialis and Rectus femoris, and Vastus lateralis all showed significant differences(p<0.05). During backward walking in 4km/h, By the difference in slope, Vastus medialis and Vastus lateralis showed significant differences between 0% and 10% gradient(p<0.05). Conclusion: In comparison to muscle activity of Quadriceps femoris when apply a taping according to slope and speed during forward and backward walking on treadmill, when apply a taping and walk backward and 10% gradient on treadmill in 4km/h, maximum of muscle activity is shown.

• Animal cells and systems
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• v.3 no.2
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• pp.153-159
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• 1999

In an artificial pH-gradient batch culture system, the effects of acidification on the species composition of a heterotrophic bacterial community were analyzed. As a result of this study, it was found that total bacteria numbers were not affected by acidification and that the population of hetero-trophic bacteria decreased as pH became lower. The heterotrophic bacteria isolated from the entire pH gradient were 12 genera and 22 species. Among them, 64% were gram negative and 36% were gram positive bacteria. As pH decreased, the distribution rate of gram negative bacteria increased while that of gram positive bacteria decreased. The diversity of genera decreased from 13 to 5 as pH decreased from 7 to 3. The G+C content of all of the 202 isolated strains varied from 22.8 to 77.0%, and increased in interspecies of same genus as pH decreased. As a result of clustering analysis, the diversity index of species ranged from 1.13 to 2.37, and it had lower indices as pH decreased. In order to evaluate the diversity of numbers of sample of different size, a rarefaction method was used to analyze the expected number of species appearance according to pH. The statistical significance of species diversity was verified by the fact that the number decreased at lower pH.

• KSBB Journal
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• v.16 no.5
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• pp.523-525
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• 2001

Curdlan is one biopolymer composed of ${\beta}$1,3-glucan and dissolved in a alkali solution but formed salt under neutral or acid condition. It was produced by Agrobactrium species and the separation process is necessary to make pure curdlan from the culture broth. The pH swing separation method was as feasible separation process using solubility changes with the pH difference. however, this method requires a lot of acid and alkali solution also produces a lot of waste. Therefore, an efficient process which could save energy and minimize toxic waste was developed. A density gradient separation process was developed in this research. High density sucrose solution was used as a separation agent. Curdlan was separated from the culture broth when the density of the sucrose solution was 1.15 g/L. Since the curdlan was produced on the surface of cell wall. the pre-treatment of culture broth was necessary. Curdlan recovery yield was increased up to 83% with the homogenization of the culture broth and further increased up to 87% with the treatment of alkai-acid solution.

• Journal of Environmental Science International
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• v.11 no.7
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• pp.705-711
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• 2002

In order to determine the factors causing Microcystis spp. bloom in the lower Nakdong River (Mulgum), we prepared wide ranges of pH, nutrient(N, P) concentration and the light through an enclosure experiment far 10days (pH gradient. 6.5, 7.5, 8.5, 9.5; gradient of N, P: ${\frac{1}{2}}DW+{\frac{1}{2}}River$ Water (RW), RW only; four different levels of nutrient addition/day; light: 100, 85, 60, 30, 15% of full sun light). From three days, the difference of Microcystis density in each enclosures was observed. The high density of Microcystis was maintained in the treatments over pH 9.5 and 85% of full sun light. However, in all nutrient treatments, relatively lower cell density than that of pH and light treatments was observed. These results suggested that pH and light input may play more important roles than nutrients in the early development of Microcystis bloom in the eutrophic lower Nakdong River.

• Korean Journal of Microbiology
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• v.33 no.3
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• pp.175-180
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• 1997

In an artificial pH-gradient hatch culture system, the author analyzed the effects of acidification on the species composition of heterotrophic bacteria. As the result of this study, it was found that the numbers of total bacteria were not affected by acidification and that the population size of heterotrophic bacteria decreased as pH became lower. The heterotrophic bacteria isolated from all of the pH gradient were 12 genera and 22 species. and among them, gram negative and gram positive bacteria were 64% and 36%, respectivcly. As pH decreased, the distribution rate of gram negative bacteria increased while that of gram positive bacteria decreased. Regarding to distrihution rate of genuses in each pH gradient, 13 genuses appeared at pH 7 while only 5 genuses appeared at pH 3. which means that the diversity of genera decrease as pH decreased. As a result of cluster analysis, diversity indices 01 species had ranges from 1.13 to 2.37, and decreased as pH decreased. In order to evaluate the diversity of different size samples, we analyzed the expected number of species appearance according to pH by rarefaction method. The statistical significance of species diversity was verified by the fact that the number decreased at lower pH.

• Korean Journal of Environmental Biology
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• v.20 no.1
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• pp.85-90
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• 2002

In an artificial pH-gradient batch culture system, the author analyzed the effects of acidification on the species composition of heterotrophic bacteria. As the result of this study, it was found that the numbers of total bacteria were not affected by acidification and that the population size of heterotrophic bacteria decreased as pH became lower. The heterotrophic bacteria isolated from all of the pH gradient were 12 genera and 22 species, and among them, gram negative and gram positive bacteria were 04% and 30%, respectively. As pH decreased, the distribution rate of gram negative bacteria increased while that of gram positive bacteria decreased. Regarding to distribution rate of genuses in each pH gradient, 13 genuses appeared at pH 7 while only 5 genuses appeared at pH 3, which means that the diversity of genera decrease as pH decreased. The activities of extracellular enzyme showed the ranges of $0.008-0.292\;\mu{M}\ell^{-1}\;hr^{-1}$ in bioreactor system. The enzymatic activities decreased rapidly below pH 5 and then sustained 5-38% at the lower pH values.

• Journal of Korean Society on Water Environment
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• v.29 no.4
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• pp.459-465
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• 2013

A sequencing batch reactor was operated under different pH conditions to see the influence of pH to microbial community in enhanced biological phosphorus removal (EBPR) systems. Long term influences of different steady-state pH conditions on the microbial community composition were evaluated by polymerase chain reaction (PCR)-denaturing gradient gel electrophoresis (DGGE) and fluorescence in situ hybridization (FISH). The shift in populations from polyphosphate-accumulating organisms (PAOs) to Alphaproteobacteria was observed when pH was changed from 7.5 to 7.0. Alphaproteobacteria with the typical morphological traits of tetrad-forming organisms (TFOs) eventually became dominant members. The alphaproteobacterial TFOs were the phenotype expected for glycogen-accumulating organisms (GAOs), which accumulate large amount of glycogen into the cell. The results strongly suggested that low operational pH condition encourages the appearance of the GAOs in EBPR process, significantly reducing the EBPR capacity.