• Journal of Korean Society of Environmental Engineers
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• v.34 no.5
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• pp.351-358
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• 2012

Formation of disinfection by-products (DBPs) including trihalomethans (THM), haloacetic acid (HAA) and haloacetonitriles (HAN) from chlorination of extracellular organic matter (EOM) and cells + intracellular organic matter (IOM) of Microcystis sp., a blue-green algae, during decomposed period was investigated. Microcystis sp. cells + IOM and EOM of Microcystis sp. exhibited a high potential for DBP formation. HAAFP (formation potential) was higher than THMFP during decomposed period. In the variations of HAAFP species during decomposed period, the ratio of di-HAAFP species was gradually decreased and the ratio of tri-HAAFP species was gradually increased in the case of EOM during decomposed period, while the opposite result was in the case of cells + IOM during decomposed period. In the variations of HANFP species during decomposed period, the ratio of di-HANFP species was much higher than the ratio of tri-HAAFP species.

• Korean Journal of Ecology and Environment
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• v.41 no.spc
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• pp.21-26
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• 2008

The in situ incubation experiment was carried out using $^{13}C$ tracer to determine primary productivity and fatty acid production rate in the shallow, eutrophic Shingu reservoir on 4th July. Particulate organic matter (POM) accounted for 76% in suspended particulate matter (SPM), and average concentration of chlorophyll-${\alpha}$ was $89{\mu}g\;L^{-1}$ in the euphotic layer. Total amount of chlorophyll-${\alpha}$ (Chl-${alpha}$), primary productivity and Chl-${alpha}$ specific productivity in euphotic layer were 112 mg Chl-${alpha}m^{-2}$, 3.53 g C $m^{-2}\;d^{-1}$, 32mg C mg Chl-${\alpha}^{-1}\;d^{-1}$, respectively. The fatty acid composition in newly produced organic matter and suspended organic matter didn't show any significant difference, demonstrating that autochthonous organic matter should be a major source of POM pool. In addition, the fatty acids of bacterial origin were increased through extracellular release of newly photosynthesized DOC, and closely coupled with bacterial assimilation. This result suggests that organic carbon should be actively cycled through the microbial loop in Shingu reservoir in summer.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.2
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• pp.175-180
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• 2008

The objective of this study was to investigate biosorption of organic matter on EPS(Extracellular Polymeric Substances) at different SRT(Sludge Retention Time) in a SBR(Sequencing Batch Reactor) process, which was operated with the following operation steps : Fill-React-Settle-Decant-Idle. The hydraulic retention time was set to be 24 hours. The results obtained from this study showed that the organic removal efficiency per unit microbial biomass decreased with increasing SRT, and the corresponding EPS amount also did. The percent removal of organic by biosorption increased with SRT, and it reached to 53.2% at SRT of 30 days. However, the highest biosorption per microbial biomass(48.6 mgCOD/gVSS) was found at SRT of 2 days. The EPS analysis was performed by measuring TSS, TCOD$_{Cr}$, and TKN. The EPS production per unit microbial biomass was observed to be high at a low SRT. Due to the above result, the floc formation was hindered and therefore poor settlement of sludge resulted in decreasing the COD removal efficiency. It was therefore concluded that the consideration of the system design should include the characteristic of EPS as well as other factors such as SRT, MLSS, and organic loading.

• ALGAE
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• v.21 no.2
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• pp.253-259
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• 2006

Organic substances are released from phytoplankton cells during all phases of growth. The type and amounts of organic substance excreted and the effects of nutrient limitation are often highly species-specific. Dinoflagellate, Cochlodinium polykrikoides grown in batch culture produced an exopolysaccharide. Exopolysaccharide and intracellular polysaccharide concentrations increased as C. polykrikoides cultures progressed from exponential phase, through stationary phase, to declining phase. In the exponential phase, the concentration of exopolysaccharide was relatively low, but in the stationary phase, it showed a rapid increase which seemed to coincide with the depletion of nitrate from the medium. Of the 20 amino acids analyzed, proline dominated in the organic matter of all cultures ranging from 48.2 to 79.9 nmol L–1, and constituting the 20-90% of total amino acids, and followed by histamine varying from 0.7 to 47.5 nmol L–1. Leucine and cysteine were also abundant in the stationary phase. The release rates of exopolysaccharide and intracellualr polysaccharide were higher the end of stationary phase than in the exponential phase. Exopolysaccharide concentration per cell was more than two times higher during the end of stationary phase than that in exponential phase. C. polykrikoides produced extracellular polysaccharide at a rate of 47.04 pg cell–1 day–1.

• Membrane and Water Treatment
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• v.14 no.3
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• pp.141-146
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• 2023

Algal organic matters (AOMs) are challenging to remove using traditional water treatment methods. Additionally, they are recognized as disinfection by product (DBP) precursors during the chlorination process. These compounds have the potential to seriously harm aquatic creatures. Despite the fact that AOMs and DBPs formed from algae can harm aquatic species by impairing their cognitive function and causing behavioral problems, only a few studies on the effects of AOMs and associated DBPs have been conducted. To assess the impact of extracellular organic materials (EOMs) produced by three different hazardous algal species and the chlorinated EOMs on zebrafish, this study used fish acute embryo toxicity (FET) and cognitive function tests. With rising EOM concentrations, the embryo's survival rate and mental capacity both declined. Of the three algal species, the embryo exposed to Microcystis aeruginosa EOM exhibited the lowest survival rate. On the other hand, the embryo exposed to EOMs following chlorination demonstrated a drop in CT values in both the survival rate and cognitive ability. These findings imply that EOMs and EOMs treated with chlorine may have detrimental effects on aquatic life. Therefore, an effective EOM management is needed in aquatic environment.

• Korean Journal of Microbiology
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• v.51 no.2
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• pp.97-107
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• 2015

Wetlands constitute a transitional zone between terrestrial and aquatic ecosystems and have unique characteristics such as frequent inundation, inflow of nutrients from terrestrial ecosystems, presence of plants adapted to grow in water, and soil that is occasionally oxygen deficient due to saturation. These characteristics and the presence of vegetation determine physical and chemical properties that affect decomposition rates of organic matter (OM). Decomposition of OM is associated with activities of various extracellular enzymes (EE) produced by bacteria and fungi. Extracellular enzymes convert macromolecules to simple compounds such as labile organic carbon (C), nitrogen (N), phosphorus (P), and sulfur (S) that can be easily taken up by microbes and plants. Therefore, the enzymatic approach is helpful to understand the decomposition rates of OM and nutrient cycling in wetland soils. This paper reviews the physical and biogeochemical factors that regulate extracellular enzyme activities (EEa) in wetland soils, including those of ${\beta}$-glucosidase, ${\beta}$-N-acetylglucosaminidase, phosphatase, arylsulfatase, and phenol oxidase that decompose organic matter and release C, N, P, and S nutrients for microbial and plant growths. Effects of pH, water table, and particle size of OM on EEa were not significantly different among sites, whereas the influence of temperature on EEa varied depending on microbial acclimation to extreme temperatures. Addition of C, N, or P affected EEa differently depending on the nutrient state, C:N ratio, limiting factors, and types of enzymes of wetland soils. Substrate quality influenced EEa more significantly than did other factors. Also, drainage of wetland and increased temperature due to global climate change can stimulate phenol oxidase activity, and anthropogenic N deposition can enhance the hydrolytic EEa; these effects increase OM decomposition rates and emissions of $CO_2$ and $CH_4$ from wetland systems. The researches on the relationship between microbial structures and EE functions, and environmental factors controlling EEa can be helpful to manipulate wetland ecosystems for treating pollutants and to monitor wetland ecosystem services.

• Mycobiology
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• v.31 no.3
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• pp.166-172
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• 2003

Chemical analysis of salted fish was analyzed in 60 samples collected from various moloha markets in Sohag, Qena and Aswan Governorates, Upper Egypt. Moloha contained 52.9% water content, while organic matter content represented 71.79% of dry weight and 33.81%($338.12{\pm}8.64mg\;g^{-1}$) of fresh weight. Total salts and soluble salts represented 13.29% and 10.19%($132.88{\pm}7.65\;and\;101.93{\pm}5.76mg\;g^{-1}$ of fresh weight), respectively. pH values were more or less neutral. Mycological investigation of examined samples revealed that fifty-five fungal species and one variety belonging to 11 genera were identified. The fungal genera of highest occurrence and their respective number of species were Aspergillus(A. flavus, A. niger, A. fumigatus, A. montevidensis, A. ficuum, A. parasiticus and A. mangini) and Penicillium(P. citrinum, P. puberulum, P. aurantiogriseum and P. roquefortii). On the other hand, yeast represented 18.2% and 3.0% of total counts of fungi on Czapeks-dextrose agar and 15%NaCl-Czapeks-dextrose agar media, respectively. Samples were assayed for potential presence of mycotoxins. Ten out of 60 samples(16.7%) were proved to be toxic. It is the first record of mycotoxins contamination of salted fish in Egypt. The ability of 340 isolates of recovered fungi was screened for production of mycotoxins and extracellular enzymes.

• Journal of Ecology and Environment
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• v.40 no.1
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• pp.5-11
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• 2016

Background: As the decomposition of lignocellulosic compounds is a rate-limiting stage in the nutrient mineralization from organic matters, elucidation of the changes in soil enzyme activity can provide insight into the nutrient dynamics and ecosystem functioning. The current study aimed to assess the effect of thinning intensities on soil conditions. Un-thinned control, 20 % thinning, and 30 % thinning treatments were applied to a Larix kaempferi forest, and total carbon and nitrogen, total carbon to total nitrogen ratio, extractable nutrients (inorganic nitrogen, phosphorus, calcium, magnesium, potassium), and enzyme activities (acid phosphatase, ${\beta}$-glucosidase, ${\beta}$-xylosidase, ${\beta}$-glucosaminidase) were investigated. Results: Total carbon and nitrogen concentrations were significantly increased in the 30 % thinning treatment, whereas both the 20 and 30 % thinning treatments did not change total carbon to total nitrogen ratio. Inorganic nitrogen and extractable calcium and magnesium concentrations were significantly increased in the 20 % thinning treatment; however, no significant changes were found for extractable phosphorus and potassium concentrations either in the 20 or the 30 % thinning treatment. However, the applied thinning intensities had no significant influences on acid phosphatase, ${\beta}$-glucosidase, ${\beta}$-xylosidase, and ${\beta}$-glucosaminidase activities. Conclusions: These results indicated that thinning can elevate soil organic matter quantity and nutrient availability, and different thinning intensities may affect extractable soil nutrients inconsistently. The results also demonstrated that such inconsistent patterns in extractable nutrient concentrations after thinning might not be fully explained by the shifts in the enzyme-mediated nutrient mineralization.

• Korean Journal of Ecology and Environment
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• v.34 no.3 s.95
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• pp.166-174
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• 2001

The autochthonous and allochthonous organic carbon loading were measured in Lake Soyang, to estimate the amount of carbon loading into the lake and the contribution of their sources to tile lake's carbon loading. Autochthonous carbon loading was estimated from phytoplankton primary production with the extracellular organic carbon (EOC). Allochthonous loading was determined by measuring dissolved organic carbon (DOC) and particulate organic carbon (POC) concentration in the main inflowing Soyang River. Both autochthonous and allochthonous organic carbon loading were high during the svmmer, from July to September, and accounted for 43.2% and 71.7% of the annual loading, respectively. Primary productivity was elevated up to $1,000\;mgC\;m^{-2}\;d^{-1}$ during summer and lowest in winter. EOC production from phytoplankton was also large in summer, resulting in a high DOC concentration in the lake water. Primary production of phytoplankton and allochthonous organic matter loading from the watershed contributed to 53.6% and 46.4% of total loading, respectively. The EOC production accounted far $4.4{\sim}21.2%$ of POC primary production, implying that EOC production of phytolankton must be considered in estimation of primary production.

• Korean Journal of Microbiology
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• v.36 no.2
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• pp.130-135
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• 2000

Decomposition rate of organic matiter in the mud flat of Sunchon Bay was estimated. Physicochemical parameters, cellulose degradation rate. distribution of heterotrophic bacteria, and extracellular enzymatic activities were measured from August 1997 to July 1998. Soil temperatures, water contents, concentration of $PO_4$-P and organic matter were -1-~$30^{\circ}C$, 42.1-53.1%, 0.0779-0.1961 mgig and 1.99-7.64%, respectively. Decomposition rate of cellulose film ranged from 7.7 to 100%imonth, high in summer and low in winter. The number of heterotrophic bacteria ranged from $0.87{\times}10^6 to 3.6{\times}10^7 $CUFsIg dq soil. Enzymatic activities of phosphatase, $\alpha$-D-gluEosidase, $\beta$-D-glucosidase and cellobiohydrolase, which were measured as decomposition rate of methylumbelliferyl(MLiF)-substrate, were 152.23-1779.80 nMIhr, 2.67-202.18 nM/hr, 5.03-258.26 M h r and 3.42-63.07 nM/hr, respectively Cellulose degradaaon rate and extracellular extracellular enzymatic activities were conelated with each other, and showed high correlation coefticiency with soil temperature.