The removal of nitrogen compounds from a wastewater is essential and it is often accomplished by biological process. An aerobic nitrate-removing bacterium was isolated from a municipal sewage treatment plant and soil. On the basis of its morphological, cultural and physiological characteristics and 16S rRNA sequencing data, this strain was identified as Pseudomonas fluorescens, and named as P. fluorescens K4. The optimal conditions of the initial pH and temperature of media for its growth were 7.0~8.0 and 30℃, respectively. P. fluorescens K4 was able to remove 99.9% of nitrate after 24 h in a culture. The strain could grow with a nitrate concentration up to 800 mg/l and was able to remove 99.9% of nitrate after 104 h of incubation. The optimal electron donor was sodium citrate for a nitrate removal. The strain K4 showed a capability of a complete nitrate removal when the initial C/N ratio was 1.0. An effect of the initial seed concentration was observed for a cell of 10% (v/v) for a nitrate removal. Especially P. fluorescens K4 could completely remove 200 mg/l ammonium for 3 days.

To investigate the influence of the mesophyll cells on stomatal opening in response to white light, the segments of isolated epidermis were transferred on partly exposed mesophyll cells of a leaf and stomatal apertures were measured. Transferring the isolated epidermis on partly exposed mesophyll cells of a leaf caused a marked increase on stomatal apertures while stomata in isolated epidermis incubated in MES buffer hardly opened. Mesophyll infiltration with photosynthetic inhibitors (DCMU, DCCD, NaN3) was performed to elucidate the correlation between stomatal apertures and the degree of photosynthetic activity. It was found that transferring the isolated epidermis on partly exposed mesophyll cells of a leaf caused an increase of stomatal apertures depending on the degree of photosynthetic activities. In NaN3 infiltrated leaf discs, transferring the fresh isolated epidermis on partly exposed mesophyll cells of a leaf showed no significant effect, but a slight increase on stomatal apertures. Isolated epidermis alone did not respond to the light properly, but if it was closely contacted with mesophyll cells, the stomata regained the ability of the light response. Therefore, it could be suggested that stomatal apertures were related with the degree of photosynthetic activity in the mesophyll cells.

Regeneration ability of plant is very important for producing transgenic plants by genetic engineering. Fifty rice cultivars and lines were screened for their regeneration ability in vitro and an attempt was made to increase shoot regeneration by substitu

The main purpose of this study was to investigate the characteristics of cylindrical electrostatic precipitator with centrifugal effect in viewpoints of pressure drop and collection efficiency, experimentally. The experiment was carried out for the analysis of current-voltage, pressure drop and collection efficiency with various experimental parameters such as the applied voltage, inlet velocity, inlet size and inlet type(upper and bottom), etc. In the results, the pressure drops were estimated as 27∼54, 34∼63㎜H2O for inlet size 15㎜×3O㎜ and 30㎜×60㎜, respectively. The collection efficiencies were shown over 99% with the small inlet size(15㎜×30㎜) for the applied voltage 40㎸, inlet velocity(15∼21m/s), and 51∼89% with the large inlet size(30㎜×60㎜). Moreover, in the applied voltage 0㎸ and inlet size 15㎜×30㎜, the collection efficiency induced by centrifugal force was represented as about 35% with inlet velocity 15∼21m/s.

ABA and SA showed different effect on stomatal closing on same condition. The addition of 1 mM salicylic acid to fully opened stomata resulted in a significant reductionn of 22 % in stomatal aperture. However, 1 mM ABA reduced 73 % of stomatal aperture. The light absorption spectra of the salicylic acid solution showed that SA was degraded within 1 hour. Therefore, SA solution was resupplied to the detached epidermis every 30 min. during incubation and it was found that even at 10 μM SA induced stomatal closing significantly. Its effect was also greatly pH dependent. The reduction of stomatal aperture caused by 1 mM SA was most effective at lower pH (pH 7.2, 5 %; pH 6.2, 40 %; pH 5.2, 78 %). Therefore, if SA was properly treated to the epidermal strips in the medium, the effects of SA on stomatal closing were similar with those of ABA.