• Ecology and Resilient Infrastructure
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• v.4 no.2
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• pp.93-96
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• 2017

Spatial variations of physicochemical and microbiological variables were examined to understand spatial heterogeneity of those variables in intertidal flat. Variograms were constructed for understanding spatial autocorrelations of variables by a geostatistical analysis and spatial correlations between two variables were evaluated by applications of a Cross-Mantel test with a Monte Carlo procedure (with 999 permutations). Water content, organic matter content, pH, nitrate, sulfate, chloride, dissolved organic carbon (DOC), four extracellular enzyme activities (${\beta}-glucosidase$, N-acetyl-glucosaminidase, phosphatase, arylsulfatase), and bacterial diversity in soil were measured along a transect perpendicular to shore line. Most variables showed strong spatial autocorrelation or no spatial structure except for DOC. It was suggested that complex interactions between physicochemical and microbiological properties in sediment might controls DOC. Intertidal flat sediment appeared to be spatially heterogeneous. Bacterial diversity was found to be spatially correlated with enzyme activities. Chloride and sulfate were spatially correlated with microbial properties indicating that salinity in coastal environment would influence spatial distributions of decomposition capacities mediated by microorganisms. Overall, it was suggested that considerations on the spatial distributions of physicochemical and microbiological properties in intertidal flat sediment should be included when sampling scheme is designed for decomposition processes in intertidal flat sediment.

• The Microorganisms and Industry
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• v.26 no.1
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• pp.18-30
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• 2000

Three kinds of organic matter such as glucose, oxalic acid, and ethanol were added to the media(N-free or NO$\_$3/-riched) and their effects on the nitrogen fixation of Nostoc pruniforme were measured by manometric technique through the experiments in vivo. 1) The organic matters used in this experiments showed effective results as a role of substrate for the fixation of atmospheric nitrogen. 2) In the nitrogen-free medium treated with the both of flucose nad ethanol, the highest nitrogen uptakes were detected in the treated of low concentrations (glucose ; 0.1%, 0.5%, ethanol : 0.1%, 0.5%). On the contrary, the highest nitrogen uptakes in NO$\_$3/-riched medium were measured at the treated of high concentrations (glucose ; 2%, 1%, ethanol ; 1.5%, 1.0%). 3) The highest nitrogen uptakes in N-free medium treated with oxalic acid were measured at the concentration of 2% and 1%, respectively. In the medium of NO$\_$3/-riched, the nitrogen uptakes were in the opposite directions.

• Korean Journal of Environmental Biology
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• v.17 no.1
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• pp.59-69
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• 1999

Bacterial population, signal compounds of pollution, bacterial productivity, heterotrophic activity and the activities of extracellular enzymes were analyzed four times from July 1994 to April 1995 at Daejin, Galnam, Pohang, and Ulsan in the coastal area of Bast Sea in order to investigate the state of eutrophication. The population of heavy metal resistant bacteria in Pohang was the highest among all stations. The bacterial populations which could utilize C -P compounds (phosphonate) showed the highest at Pohang that was expected for the industrial and agricultural effluents to inpour. It could be useful as an index of expectation about the influx of industrial sewages and agricultural effluents. The activities of extracellular enzymes for the degradation of organic matter were the highest in the Ulsan Chuyongam, but low in Daejin. These results showed positive relationship with the population of heterotrophic bacteria and bacterial productivity The ratio of poly-P and DNA in Pohang was the highest, and that in Ulsan, Galnam, and Daejin consecutively, corresponding with the distribution of heterotrophic bacteria. In case of the heterotrophic activities, each of the stations gives difference of seasonal variation in heterotrophic activities. Bacterial productivity seemed to be dependent on seasons; the highest in summer and the lowest in fall and winter. These seasonal variations of bacterial productivity seems to be similar with those of heterotrophic bacteria. It is suggested that the state of eutrophication could be evaluated by the criteria of the population sizes and the productivities of microorganisms, the amount of poly-P, heterotrophic activity, the activities of extracellular enzymes, etc.

• Journal of Microbiology
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• v.42 no.4
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• pp.267-277
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• 2004

Effects of elevated $CO_2$ on soil microorganisms are known to be mediated by various interactions with plants, for which such effects are relatively poorly documented. In this review, we summarize and syn­thesize results from studies assessing impacts of elevated $CO_2$ on soil ecosystems, focusing primarily on plants and a variety the of microbial processes. The processes considered include changes in microbial biomass of C and N, microbial number, respiration rates, organic matter decomposition, soil enzyme activities, microbial community composition, and functional groups of bacteria mediating trace gas emission such as methane and nitrous oxide. Elevated $CO_2$ in atmosphere may enhance certain micro­bial processes such as $CH_4$ emission from wetlands due to enhanced carbon supply from plants. How­ever, responses of extracellular enzyme activities and microbial community structure are still controversy, because interferences with other factors such as the types of plants, nutrient availabilitial in soil, soil types, analysis methods, and types of $CO_2$ fumigation systems are not fully understood.

• Korean Journal of Ecology and Environment
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• v.34 no.1 s.93
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• pp.20-29
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• 2001

The amount, chemical composition and optical property of extracellular dissolved organic carbon (EOC) by phytoplankton were examined using axenic cultures of Microcystis aeruginosa, Anabaena flos-aquae, and Oscillatoria agardhii. The extracellular organic matter was categorized into five fractions (hydrophobic acids; AHSs, hydrophobic neutrals; HoNs, hydrophilic acids; HiAs, hydrophilic bases; HiBs, and hydrophilic neutrals; HiNs) using three adsorbent resins(XAD-8, cation, and anion). The release pattern and chemical composition of EOC varied with algal species and their growth phases. Percentage of extracellular release increased with age in all cultures. HiAs were the dominant component of EOC in all cultures, whereas the proportion of HiAs decreased with age in all cultures. In contrast, the proportions of HiBs and HiNs increased as cultures aged. In particular, the HiN fraction increased from 0% to 44% of EOC in M. aeruginosa and from 3.0% to 28% in A. flos-aquae, respectively. The proportion of AHSs was higher in the cultures of A. flos-aquae(7.5${\sim}$16%) and O. agardhii (8.7${\sim}$16%) than M. aeruginosa(0.2${\sim}$2.5%). The proportions of AHSs increased with culture age in M. aeruginosa and O. agardhii, but decreased in A. flos-aquae. The specific UV absorbance also varied among species; 1.9 Abs${\cdot}$cm$^{-1}$/mgC${\cdot}$L$^{-1}$ for M. aeruginosa, 3.7 Abs${\cdot}$cm$^{-1}$/mgC${\cdot}$L$^{-1}$ for A. flos-aquae, and 13.0 Abs${\cdot}$cm$^{-1}$/mgC${\cdot}$L^{-1}$ for O. agardhii. The results of this study indicates that DOC excreted by three blue-green algae differed with species and the growth phase.

• Korean Journal of Soil Science and Fertilizer
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• v.21 no.3
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• pp.339-345
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• 1988

Four actinomycetes which produces extracellular chitinase were isolated from soil and organic matter all over the Chonnam provincial area. The chemical composition, morphological, cultural and physiological properties of isolated strain S-25, S-42, S-172 and S-267 were studied in relation to the toxonomical properties. All of strains contained phospholipids such as phosphatidyl ethanolamine, phosphatidyl inositol and diphosphatidyl glycerol. The components of cell wall in all strains have L, L-DAP, Glutamic acid, Alanine, Glycine and Glucosamine. The surface of spore is smooth and colony is grey in all strains, Based on the results obtained in these experiments all of strains are identified as Streptomyces sp.S-25, Streptomyces sp.S-42, Streptomyces sp.S-l72 and Streptomyces sp. S-267.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.5
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• pp.246-254
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• 2017

Microcystin-LR (MC-LR) is one of most abundant microcystins, and is derived from blue-green algae bloom. Advanced oxidation processes (AOPs) are effective process when high concentrations of MC-LR are released into a drinking water treatment system from surface water. In particular, UV-based AOPs such as UV, $UV/H_2O_2$, $UV/O_3$ and $UV/TiO_2$ have been studied for the removal of MC-LR. In this study, UV-LED was applied for the degradation of MC-LR because UV lamps have demonstrated some weaknesses, such as frequent replacements; that generate mercury waste and high heat loss. Degradation efficiencies of the MC-LR (initial conc. = $100{\mu}g/L$) were 30% and 95.9% using LED-L (280 nm, $0.024mW/cm^2$) and LED-H (280 nm, $2.18mW/cm^2$), respectively. Aromatic compounds of natural organic matter changed to aliphatic compounds under the LED-H irradiation by LC-OCD analysis. For application to raw water, the Nak-dong River was sampled during summer when blue-green algae were heavy bloom in 2016. The concentration of extracellular and total MC-LR, geosmin and 2-MIB slightly decreased by increasing the LED-L irradiation; however, the removal of MC-LR by UV-LED (${\lambda}=280nm$) was insufficient. Thus, advanced UV-LED technology or the addition of oxidants with UV-LED is required to obtain better degradation efficiency of MC-LR.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.11
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• pp.1054-1062
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• 2010

Oxidative coupling reactions of humic substances (HS) can be catalyzed by a variety of natural extracellular enzymes and metal oxides. In this study, property changes of HS induced by a natural enzyme, horseradish peroxidase (HRP), and the effect of it to microfiltration (MF) were investigated. PAHA was transformed by oxidative coupling reaction with HRP and hydrogen peroxide ($H_2O_2$), verifying the catalytic effects of the HRP. Size exclusion chromatography (SEC) revealed that weight-average molecular weight (MWw) of PAHA was proportionally increased with the dosages of HRP and $H_2O_2$, indicating the transform action of HS into larger and complex molecules. An increase in the conformational stability of HS was achieved through the promotion of intermolecular covalent bondings between heterogeneous humic molecules. Spectroscopic analysis (fluorescence and infrared spectroscopy) proved that functional groups were transformed by the reaction. Additionally, HS and transformed products were undergone microfiltration (MF) to examine the treatment potential of them in a water treatment facility. Original HS could not be removed by MF but larger molecules of transformed products could be removed. Meanwhile, transformed products caused more fouling on the filtration than original HS. This results proved that natural organic matter (NOM) can be removed by MF after its increase in molecular size by oxidative coupling reaction.