• 한국지하수토양환경학회지:지하수토양환경
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• 제20권7호
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• pp.70-79
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• 2015

A sample of soil humic acid (HA) was divided by ultrafiltration (UF) into five fractions of different molecular size (UF₁: > 300, UF₂: 100~300, UF₃: 30~100, UF₄: 10~30, UF₅: 1~10 kilodaltons). Apparent average molecular weight (M_w) of the HA fractions were measured using high performance size exclusion chromatography (HPSEC), and the chemical and structural properties of the five HA fractions were characterized by elemental compositions (H/C, O/C and w ((2O + 3NH)/ C)) and ultraviolet-visible absorption ratios (SUVA, A_4/6). The organic carbon normalized-sorption coefficients (Koc) for the binding of phenanthrene to the HA fractions were determined by fluorescence quenching and relationship between the sorption coefficients and structural characteristics of the HA fractions were investigated. The elemental analysis and UV-vis spectral data indicated that the HA fractions with higher molecular weights have grater aliphatic character and lower contents of oxygen, while the HA fractions with lower molecular size have greater aromatic character and molecular polarity that correspond to greater SUVA and internal oxidation values (w). The log Koc values (L/kg C) were gradual increased from 4.45 for UF₅ to 4.87 for UF1. The correlation study between the structural descriptors of the HA fractions and log Koc values of phenanthrene show that the magnitude of Koc values positively correlated with $M_w$ and H/C, while negatively correlated with the independent descriptors of the O/C, w, SUVA and A_4/6.

• 한국환경농학회지
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• 제25권4호
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• pp.289-296
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• 2006

Various drying conditions, temperatures (40 to $80^{\circ}C$) and durations (overnight to 72 hrs), for the particulate organic matter (POM) fraction after wet-sieving size fractionation have been applied for determination of POM contents in the weight loss-on-ignition method. In this study, we investigated the optimum drying condition for POM fraction in quantification of POM and/or mineral-associated organic matter (MOM; usually indirectly estimated). The influence of the drying conditions on quantifying POM was dependent upon soil properties, especially the amount of soil organic components. In relatively high organic soils (total carbon > 40 g/kg in this study), the POM values were significantly higher (overestimated) with drying at $55^{\circ}C$ than those values at $105^{\circ}C$, which were, for example, 173.2 and 137.3 mg/kg, respectively, in a soil studied. However, drying at $55^{\circ}C$ for longer than 48 hrs of periods produced consistent POM values even though the values were much higher than those at $105^{\circ}C$. Thus, indirect estimates of MOM (MOM = SOM-POM) also tended to be significantly impacted by the dry conditions. Therefore, we suggest POM fractions should be dried at $105^{\circ}C$ for 24 hrs as determining POM and MOM contents. If the POM traction is needed to be dried at a lower temperature (e.g. $55^{\circ}C$) with a specific reason, at least 48 hrs of drying period is necessary to obtain consistent POM values, and a moisture correction factor should be determined to adjust the values back to a $105^{\circ}C$ weight basis.

• 한국토양비료학회지
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• 제24권3호
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• pp.183-191
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• 1991

본 연구는 아연광산(亞鉛鑛山) 주변의 논토양에 존재하는 Cd, Pb, Cu 및 Zn의 형태별 함량을 조사하여 중금속간의 분포(分布) 특성(特性)을 검토하였으며, 토양 화학적 성질이 이들의 형태별 함량 분포에 미치는 영향을 밝히기 위하여 수행되었다. 그 결과를 요약하면 다음과 같다. 1. 공시토양에 존재하는 Cd, Pb, Cu 및 Zn은 주로 해화물-잔류태(殘留態)로 존재하였으며, Cd와 Pb의 산화물(酸化物)-탄산염태(炭酸鹽態)와 Cu의 유기복합태(有機複合態)의 함량도 높은 편이었다. Pb와 Cu의 치환태는 소량 존재하였으며, 수용태는 Zn만 검출되었다. 2. 치환태의 분포비가 높은 토양일수록 산화물-탄산염태 및 황화물-잔류태의 분포비가 낮았다. 3. 토심이 깊어질수록 치환태 Cd 및 Zn의 분포비(分布比)는 낮아지고 항화물-잔류태의 분포비가 높아졌으며, Pb는 산화물-탄산염태의 분포비가 낮아지고 황화물-잔류태의 분포비가 높아졌다. 4. Cu는 유기물이 많은 토양일수록 Cu의 유기복합태 함량이 많았으며, Cd, Pb 및 Zn의 유기복합태는 유기물함량과 관계가 없었다. 치환태 Cd, Pb 및 Zn의 분포비는 pH가 높은 토양일수록 낮았으나, 이들의 산화물-탄산염태과 황화물-잔류태의 분포비의 합은 높았다. Pb의 산화물-탄산염태 및 황화물-잔류태의 분포비는 공시토양의 pH 전범위에서 Cd 및 Zn에 비하여 높았다.

• 한국토양비료학회지
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• 제24권4호
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• pp.248-253
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• 1991

담수처리(湛水處理)에 의한 토양(土壤)의 환원(還元)이 토양(土壤)중 인산(燐酸) 및 철화합물(鐵化合物)의 형태변화(形態變化)와 인산(燐酸) 흡착량(吸着量)과의 관계(關係)에 어떠한 영향(影響)을 미치는지를 검토(檢討)하기 위하여 논으로 이용(利用)되어온 강서통(江西統), 밭으로 이용(利用)되어온 중동통(中東統), 및 미경작지(未耕作地)인 예산통(禮山統)을 공시토양(供試土壤)으로 하여 $28^{\circ}C$에서 17일간 담수처리후(湛水處理後) 무기태(無機態) 인산(燐酸) 및 철산화물(鐵酸化物)의 분별정량(分別定量)을 실시(實施)하였다. 얻어진 결과(結果)를 요약(要約)하면 다음과 같다. 1. 담수처리(湛水處理)에 의하여 토양(土壤)의 Bray 1-P의 함량(含量)은 강서통(江西統)은 53mgP/kg에서 48mgP/kg으로, 예산통(禮山統)은 3mgP/kg에서 1mgP/kg으로, 중동통(中東統)은 120mgP/kg에서 56mgP/kg으로 감소(減少)하였다. 2. 새로 흡착(吸着)된 인산(燐酸)의 주(主) 형태(形態)는 $NH_4F-P$이었으며, 토양(土壤)중 토양(土壤)의 함량(含量)이 높은 중동통(中東統)의 경우에는 담수처리(湛水處理)에 의하여 $NH_4F-P$가 NaOH-P로 전환(轉換)되었다. 3. 강서통(江西統)과 중동통(中東統)은 담수처리(湛水處理)에 의하여 철산화물(鐵酸化物)의 형태(形態) 변화(變化)가 거의 없었으나, 예산통(禮山統)에서는 담수처리(湛水處理)에 의하여 dithionite-citrate-bicarbonate 침출(浸出) Fe의 대부분이 oxalate침출(浸出) Fe로 전환(轉換)되었다.

• Journal of Microbiology and Biotechnology
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• 제6권3호
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• pp.184-188
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• 1996

The Acinetobacter sp. BE-254 isolated from soil sources produced a bioemulsifier in the medium supplemented with n-hexadecane. This bioemulsifier was purified by the procedures of fractionation (ammonium sulfate and chilled acetone), extraction by hexane, and column chromatography on silica gel 60. The results from various color reactions indicated that the bioemulsifier was a glycolipid. The purified emulsifier was very stable at pHs ranging from 4 to 10 and under heat treatment at $100^{\circ}C$ for 30 min. Emulsification activity was also hardly influenced by pH. The critical micelle concentration (CMC) and surface tension at the point ($\gamma_{cmc}$) of the bioemulsifier were approximately 35 mg/l and 30 mN/m, respectively. The bioemulsifier showed a fairly good emulsification activity and stability in comparison with other commercial emulsifiers in the basic formula composed of emulsifier, oil, and water.

• Journal of Microbiology and Biotechnology
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• 제1권2호
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• pp.85-89
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• 1991

The aim of this study is to elucidate characteristics of ${\beta}-lactamase$ inhibitor produced by Streptomyces sp. SMF-19 isolated from soil was found to produce proteinaceous extracellular ${\beta}-lactamase$ inhibitor. The ${\beta}-lactamase$ inhibitor was purified through ammonium sulfate fractionation, gel filtration, anion exchange chromatography and fast performace liquid chromatography. The molecular weight of the ${\beta}-lactamase$ inhibitor was estimated to be about 48,000 by SDS-PAGE. The mode of inhibition against penicillin G as a substrate was uncompetitive. The ${\beta}-lactamase$ inhibitor was stable in wide pH range but unstable at high temperature above $50^{\circ}C$.

• 한국미생물·생명공학회지
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• 제19권5호
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• pp.439-443
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• 1991

A strain of Streptomyces sp. isolated from soil was found to produce extra-cellular $\beta$-lactamase associated partially to the cell growth. The $\beta$-lactamase was purified from the culture supernatant through anmonium sulfate fractionation, ion-exchange chromatographies and gel filtration. The final purification fold and recovery yield were 57 and 6.2%, respectively. Molecular weight of the $\beta$-lactamase was estimated to be about 67, 000 by SDS-polyacrylamide gel electrophoresis. The optimal reaction condition was at pH 7-8 and at 35-$45^{\circ}C$. The $K_m$ and $V_{max}$ values of the enzyme for penicillin G were estimated to he 3 mM and $3\times 10^3$ $\mu\textrm{M}$/min/mg protein, respectively. The purified $\beta$-lactamase was classified to the class A enzyme hydrolyzing only penicillin.

• Plant Resources
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• 제8권2호
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• pp.116-121
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• 2005

Compositae plants are known to contain biologically active substances that are allelopathic to agricultural crops as well as weed species. Aqueous or methanol extracts and plant residues from leaves of Xanthium occidentale were assayed against alfalfa (Medicago sativa) to determine its allelopathic effects, and the results showed that the extracts applied onto filter paper significantly inhibited seed germination as well as root growth of alfalfa. Aqueous leaf extracts of $40g\;L^{-1}$ were completely inhibitory on root growth of alfalfa, while root growths of barley (Hordeum vulgare L.) and soybean (Glycine max L.) were less sensitive. Leaf residue incorporation at $100g\;kg^{-1}$ into soil on seedling growth of barnyard grass (Echinochloa crus-galli Beauv. var. oryzicola Ohwi) inhibited both shoot and root fresh weights of barnyard grass by 94 and $96\%$, respectively. Methanol extracts from BuOn and EtOAc fractions of X. occidentale reduced alfalfa root growth more than did those from hexane and water fractions. The results based on bioassay of extracts and residues show that X. occidentale had potent an allelopathic activity against other plant species.

• 미생물학회지
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• 제32권4호
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• pp.297-300
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• 1994

토양에서 분리한 방선균에서 제한효소 활성을 조사하여 그 가운데 Streptomyces diastatochromogenes로부터 제한효소 활성을 확인하였다. 이 균주의 제한효소 SdiI을 균체 15g으로부터 streptomycin sulfate침전, ammonium sulfate 침전, hydroxylapatite colume chromatography, Sephacryl S-200 HR column chromatography, hydroxylapatite column chromatography의 단계를 거쳐 분리하였고, SDS-polyacrylamide gel-electrophoresis에 의하면 소단위체 분자량은 약 35,000Da으로 추정되었다.

• 한국물환경학회지
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• 제26권6호
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• pp.976-985
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• 2010

In this study, characteristics of dissolved organic matter (DOM) from Lake Paldang and seven other DOM sources (lake plankton, plants, soil, composite, treated sewage) were studied using XAD resin fractionation and 28-day microbial incubation experiment. Distribution patterns of DOM-fractions, which include hydrophilic acids (HiA), hydrophilic bases (HiB), hydrophilic neutrals (HiN), hydrophobic acids (HoA), hydrophobic neutrals (HoN) and the extent of DOM biodegradation (i.e., biodegradability) were different depending on the origins of the DOM samples. The DOM distribution pattern and the biodegradability were found to be effective for distinguishing the different DOM sources. The biodegradability (%) had negative correlations with the content (%) of hydrophobic fractions (Ho) and specific UV absorbance of DOM, which indicate that the Ho fractions contain more aromatic carbon structures and relatively stable during biodegradation, irrespective of the sources. To gain additional insight into the microbial transformation of the DOM, we also investigated the changes in the fraction's distribution for plankton, leaf litter and composite samples after the incubation. The results showed that biodegradation of hydrophilic fraction (Hi) causes an increase in the proportion of Ho (HoA, HoN), while biodegradation of HoA increases the HoN production.