• The Korean Journal of Ecology
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• v.19 no.2
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• pp.179-189
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• 1996

Growth and nitrogen retention of Persicaria thunbergii were investigated in the wetland microcosms which contained the plants growing on soil bed. Nitrogen solution was supplied to the microcosms with the same amount of $NH_4^{+}-N\; and\; NO_3^{-}-N$ at the rates of 0.00, 0.78, 1.57, 3.14g $N{\cdot}m^{-2}{\cdor}wk^{-1}$ from May 1 to August 31, 1995. The solution was detained for 5 days to react with soil and plant and then allowed to leach. The contents of NH_4^{+}-N\;and\; NO_3^{-}-N$ in the leachate, total Kjeldahl nitrogen, plant biomass, and soil characteristics were determined. Nitrogen retained by plant was estimated as the increment of TKN in plant biomass. The addition of 0.78 and 1.57g $N{\cdot}m^{-2}{\cdot}wk^{-1}$ resulted in significant increase of plant biomass. However, plant growth was inhibited when nitrogen was added at the rate of 3.14g $N{\cdot}m^{-2}{\cdot}wk^{-1}$. Overall, the plant biomass was positively correlated with the amount of nitrogen retained by plant and soil system. The amounts of $NO_3^{-}-N$ leached from the microcosms were 5~10 times higher than those of $NH_4^{+}-N$. While total nitrogen added ranged from 143.2 to 576.5g $N/m^2$, total leaching loss of inorganic nitrogen and nitrogen retained by plant was as little as 1.04~22.71g $N/m^2$, and 5.46~12.91g $N/m^2$, respectively. Then, the plant seemed to contribute to KDICical and microbial immobilization of nitrogen in the soil. Finally, it is suggested that a large portion of nitrogen added was lost into the air by denitrification and volatilizaton, and / or leached in organic forms.

• KSBB Journal
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• v.21 no.4
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• pp.273-278
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• 2006

The noble method of hybrid agarose gel microstamp fabricated by replica molding against PDMS master to make bacteria patterns on agar surface was presented. After the fabricated hybrid agarose gel microstamp was inked with E. coli, we could obtain 2 dimensional bacterial arrays with $50{\mu}m$ circular spots. And the various shaped patterns based on experimental design were easily generated. The analysis of mean fluorescent signal was showed that bacterial pattern have high contrast between spots and background and homogeneity of pattern. Our proposed method solved the problem of wetting and handling with small soft agarose gel microstamp when bacteria were used for ink. The agarose gel stamp provides appropriate environment to inked bacteria, which is essential technology for cell patterning with high retaining viability during the patterning process. This method is reproducible, convenient, rapid, and could be applied to screening system, study of cell-surface interaction, and microbial ecology.

• Restorative Dentistry and Endodontics
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• v.19 no.2
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• pp.372-383
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• 1994

Saliva plays an important role in modulating the oral microbial ecology. And it is suggested to influence the initiation and progression of the dental caries. To evaluate the correlations between the salivary antimicrobial agents and the caries susceptibility, the 51 subjects were divided into 3 groups according to caries experience ; caries resistant group, medium caries susceptible group, and high caries susceptible group. Stimulated whole saliva was collected, and the salivary levels were measured for lysozyme, lactoferrin, and secretory-IgA to Streptococcus mutans. The lysozyme level was estimated using Micrococcus diffusion plate, lactoferrin level was determined with a non-competitive avidin-biotin enzyme immunoassay, and the titer of secretory IgA to Streptococcus mutans was assayed with ELISA. The results were as follows: 1. Lysozyme levels of each group showed no significant difference statistically (p>0.05). 2. The caries resistant group and the medium caries susceptible group had significantly higher levels of lactoferrin than the high caries susceptible group (p<0.05). But no clear difference was observed between the caries resistant group and the medium caries susceptible group(p>0.05). 3. The caries resistant group and the medium caries susceptible group showed relatively higher levels of the secretory IgA to Streptococcus mutans than the pigh caries susceptible group, but no significant difference was observed statistically (p>0.05).

• Journal of Microbiology and Biotechnology
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• v.22 no.6
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• pp.754-762
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• 2012

Colbricon Superiore and Inferiore are two small adjacent high-mountain lakes located in the Paneveggio Natural Park (Italy) that offer the rare opportunity to study two iso-ecologic water environments differing only by area and volume in a ratio of 2:1 and 3:1, respectively. We took advantage of this setting to investigate phytoplankton dynamics, compare variability and productivity differences between the two basins, and assess size-dependent issues. The phytoplankton group of the Dinophyceae was chosen as the indicator organisms of ecological perturbation owing to their high sensitivity to environmental variations, as well as their acknowledged nature of versatile proxy to report global climatic changes. The study was conducted for over 10 years with fortnightly samplings. Results indicated that (a) the Dinophyceae communities in the smaller lake were significantly more resistant to changes exerted by the fluctuation of lakewater transparency and pH; and (b) the smaller lake sustained a consistently higher production with an average Dinophyceae density 1.73 fold higher than that of the larger lake. The coefficients of variation show that the chemical parameters in the smaller lake display higher time-related fluctuation while being spatially homogeneous and that such conditions correlate with a higher stability of the Dinophyceae assemblage. The use of this setting is also proposed as a model to test relationships between ecosystem production and physical stability.

• The Korean Journal of Ecology
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• v.21 no.5_3
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• pp.703-712
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• 1998

Physicochemical factors, microbial population size and the properties of the bacterial isolates were estimated to find out the nature of soil ecosystem of Mt. Nam. Samples were obtained from the surface layer of soils on which specific plant community is developed. Average content of moisture and organic matter of the soils were 21.6% and 17.3%, respectively. These values were similar to those of developing forest soils, but were slightly lower than those of climax ecosystem such as Piagol in Mt. Chiri. Chiri. Content of phosphate was higher than those of other forest soils. The population size of soil bacteria ranged from 27.4 to 195.8 ${\times}\;10^5$ CFU/g. duy soil, and the size is somewhat dependent on the moisture and oranic matter content of soils. A large number of bacteria were able to decompose macromolecules such as starch, elastin and gelatin. Bacterial species composition of each soil was comparatively simple. Pseudomonas, Agrobacterium, Flavobacterium and Xanthomonas which are Gram-negative short rods were widely distributed in the forest soils. The endospore forming Bacillus species were also the main constituents of the soil microflroa. Actinomycetes were widely distributed in the forest soils, but the distribution pattern varied in each site. Most of the actinomycetes were also able to decompose organic macromolecules. The rate of resistant actinomycete strains to antibiotics and heavy metals were lower than those from cultivated soils, but higher than those from well-preserved forest soils. Antibiosis pattern of the actinomycete isolates was similiar to the resistance pattern. This means the forest soils of Mt. nam was somewhat interferred by artificial behabiour.

• The Korean Journal of Ecology
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• v.21 no.5_2
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• pp.575-583
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• 1998

Physicochemical factors, microbial population size and the properties of the bacterial isolates were assessed to find out the nature of soil ecosystem of Mt. Paektu. Samples were obtained from the surface layer of soils on which specific plant community is developed. Average content of moisture, organic matter and avaiable phosphate of the soils were 21.6%, 17.3% and 2.48mg/100g, respectively. These values were similar to those of developing forest soils, but were slightly lower than those of climax ecosystem such as Piagol in Mt. Chiri. The population size of soil bacteria ranged from 2.7 to $202.5{\times}10^5$ CFU/g.dry soil, and the size is somewhat dependent on the content of moisture and oranic matter of the forest soil. A large number of bacteria was able to decompose macromolecules such as starch, elastin and gelatin. While the distribution rate of resistant bacteria to antibiotics was high, that to toxic chemicals was low. This means that the competition between microorgani는 predominate over the interference with artificial behaviour such as spread of pesticides in the surveyed region. Bacterial species composition of each soil was comparatively simple. Pseudomonas, Agrobacterium, Flavobacterium and Xanthomonas which are Gram-negative short rods were widely distributed in the forest soils. The endospore forming Bacillus species were also main constituents of the soil microflroa. any one of the strains was not identified as Azospirillum or Micrococcus which are known to be one of major constituents of the forest soil. for the correct identification of isolates chemotaxonomic studies will be proceeded, and the strains are to be stored in the Type collection Center.

• Journal of the Korean Wood Science and Technology
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• v.25 no.3
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• pp.50-57
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• 1997

The presence of slime in paper mills is practically universal. Many researches have been performed for many years to resolve the problem caused by the slime in pulp and paper mill. Many papers have been published to show the bacteria is a major cause of paper mill slime. Now that the recycling of the water has been increased and the regulations of a toxic chemical dosage have become more strengthen, the importance of the control of slime in pulp and paper mill recently has been more recognized. Therefore, to produce quality products at the lowest economic and environmental costs, a through study of the microbial ecology and the indentification of troublesome slime-forming bacteria is a quite necessary. The purpose of this paper is to indentify slime~forming bacteria isolated from the papermaking process. The samples were taken from four parts of making fine paper : machine chest, head box, wire part, white water tank. Machine chest showed the most numbers of bacteria, numbering $2.55{\times}10^7$. The different colony types were taken from the 105 dilution plate. Nine bacteria were identified u sing the Biolog system and the vitek system: 6 gram-negative bacteria, 3 gram-positive bacteria. They are Pseudomonas paucimobilis B., Staphylococcus sp., Acinetobacter calcoaceticus., Pseudomonas cepacia, Actinobaci1lus capsulatus, Acidovorax sp., Flavobacterium sp., and Staphylococcus auricularis in addition to one unidentified sp., Among them. Pseudomonas paucimobillis was found in all places where the samples were taken. And, each parts had the different predominant bacteria in it : Pseudomonas paucimobilis B. in machine chest, Acinetobactor calcoaceticus. in Wire Part and Staphylococcus sp. in head box.

• Korean Journal of Ecology and Environment
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• v.35 no.4 s.100
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• pp.326-330
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• 2002

A wetland soil was sterilised by two methods and changes in microbial enzyme activities were assessed. The short-term effects were determined by toluene addition, while the longer-term effects of elimination was monitored by ${\gamma}$-radiation. The changes in ${\beta}$- glucosidase, ${\beta}$-xylosidase, cellobiohydrolase, phosphatase, arylsulphatase, and N-acetylglucosaminidase activities were determined by using methylumbelliferyl model substrates and comparing with the activities of control samples. Toluene addition induced different responses of enzymes. For example, phosphatase activity increased by the treatment while ${\beta}$-glucosidase and arylsulphatase activities decreased. In contrast, ${\gamma}$-radiation decreased all enzyme activities compared to control by 40-80%. The overall results of the toluene and ${\gamma}$-radiation experiments indicate that the large amounts of enzymes are stabilised outside of living cells, at least in the short term, but that the persistence of enzymes is maintained by de-novo synthesis of microbes.

• Korean Journal of Ecology and Environment
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• v.35 no.4 s.100
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• pp.266-272
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• 2002

For analyzing function of a microbial ecosystem which was created under the artificial vegetation island (AVI) installed at Lake Paldang, zooplankton and bacterial numbers and exoenzyme activities (${\beta}$-glucosidase and phosphatase) were measured biweekly from 3 November 2()()1 to 20 April 2002 at AVI site and control site. Under the AVI, the water quality was worse than control site in term of comparing the environmental parameters. But, zooplankton number of AVI site was 25 times higher than that of control site. Respiratory active bacterial numbers were 3-8 times higher at AVI site. In addition, enzymatic activities were higher at AVI site than those of control site. These results suggest that the zooplankton-phytoplankton-bacteria relationships are closely coupled with each other and organic materials are eliminated by respiration of zooplankton and bacterial activities.

• Korean Journal of Soil Science and Fertilizer
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• v.48 no.4
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• pp.285-294
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• 2015

Ordination has been recognized useful method to analyze the effects of multiple environmental factors on dozens of species in vegetation ecology because of summarizing community data by producing a low-dimensional graphics. Main objective of this study was the application of ordination method, especially principal components analysis (PCA), to analyze the soil characterization on paddy treated by different green manure crops and tillage methods. Treatments included the three tillage treatments and two green manure crops as the following; (i) moldrotary + rotary tillage without green manure crop (Con), with (ii) hairy vetch (ConHv), and (iii) hairy vetch + green barely (ConHvGb), (iv) rotary tillage without green manure crop (Rot), with (v) hairy vetch (RotHv), and (vi) hairy vetch + green barly (RotHvGb), and (vii) no-tillage (Notill). Vectorial distance result from PCA of soil properties including physical, chemical, and microbial properties showed the two main difference. Firstly, soil properties among plots without green manure were strongly affected by tillage strength [Vectorial distance: Con-Notil (5.88) > Rot-Notill (4.58)] at PC1 (35.0%) axis. But it was difficult to find the fixed trend among plots when green manure crop was added in plot. Nevertheless, two groups were separated by adding green manure crop at PC2 (29.2%) axis. These results show that PCA ordination methods could be used the research for change of soil characterization.