• Ecology and Resilient Infrastructure
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• v.11 no.2
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• pp.23-34
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• 2024

Sediment, aquifer materials, surface water, and groundwater from brackish Songji lake affected by salinity of seawater, were collected and a pilot scale column experiment was conducted to simulate the nitrogen transport through the hyporheic zone. Upstream experiments of groundwater displayed that groundwater containing a small amount of salt percolated into aquifers and sediments, maintaining low dissolved oxygen concentrations. In addition, partial denitrification occurred in the aquifer due to salinity and low dissolved oxygen, resulting in the accumulation of NO₂^-. In sediments,nitrogenous compounds were reduced due to adsorption by long residence times or microbial-mediated oxidation/reduction reactions. Downstream experiments of surface water displayed that surface water from the brackish lake, containing high concentrations of dissolved oxygen and salts, infiltrated into the sediments and aquifer, supplying high dissolved oxygen concentrations. This resulted in biological nitrification in the sediments and aquifer, which reduced nitrogen-based pollutants despite the high salt concentration in the surface water. Whereas partial denitrification at low dissolved oxygen concentrations in the upwelling mixing zone was observed by salinity and accumulated NO₂^-, nitrification at high dissolved oxygen concentrations in the downwelling mixing zone was not significantly affected by salinity. These results confirm that salinity in the brackish water lake has some influence on the nitrogen behavior of the hyporheic mixing zone, although nitrogen behavior is a complex combination of factors such as DO, pH, substrate concentration, and organic matter concentration.

• Korean Journal of Microbiology
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• v.49 no.4
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• pp.424-428
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• 2013

To identify risk factors for Legionella contamination, water quality variables routinely measured in examination of natural and city waters were meta-analyzed for significance of correlation to Legionella incidences. For evaluation of abundance of Escherichia coli as a risk factor, which is currently used as an indicator of Legionella contamination in an official guideline in Korea, odds ratio (OR) of above-cutoff total coliform counts for Legionella presence/absence was used as the effect size in the meta-analysis. The OR was estimated as 1.05 (0.36-3.12, 95% CI), and the probability of having identical odds reached 0.92. Also, ORs from individual studies showed significant heterogeneity (P=0.008), which contributed to 63% of total variance of the ORs. In the case of heterotrophic plate count (HPC), the OR for Legionella presence/absence was 2.72 (2.04-3.63) with highly significant deviation from identical odds (P<0.0001). ORs from different studies were seemingly homogeneous ($Q_{df=8}$=12.7, P=0.12). Turbidity and concentrations of chlorine, iron ion and cupper ion were other routine variables that could be considered as risk factors. However, statistical measures from different studies were not uniform enough to develop an appropriate effect size while the number of studies reporting the variables was also small (3-5). In conclusion, HPC appeared to be appropriate as indicator of Legionella contamination, rather than fecal bacteria contamination. HPC may imply abundance of habitats (amoebas and biofilms) of Legionella in water. This result warrants further studies for standardizing protocols and cutoff values to infer Legionella risks from HPC.

• Korean Journal of Microbiology
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• v.39 no.1
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• pp.27-35
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• 2003

No currently available methods to monitor pathogenic protozoa, Cryptosporidium and Giardia in environmental water come close to acceptable sensitivity, specificity and reproducibility, and so it has to be accompanied by thorough quality control and performance evaluation to credibly predict the distribution of them. We collected surface water samples from the Han River and spiked our prepared (oo)cysts, determined Matrix Spike recoveries using USEPA Method 1623 and considered what factors influence MS recovery and validity. As a result, average 46% of spiked oocysts and 60% of spike cysts were recovered, but repetitive sampling and statistical approach seemed to be necessary to determine the environmental pollution level of two protozoa as their variation coefficients was so much as 35oio and 26%. And MS recoveries with two acid dissociations during immunomagnetic separation were improved more 10% than that with one dissociations and the use of spiked suspension enumerated by flow cytometry instead of manual preparation enhanced the validity and reliability in spiking tests. Because fluorescence characteristics of (oo)cysts stained on well slides with FITC-labeled monoclonal antibodies and DAPI was not always same, well Elides from spiked field samples were helpful to evaluate the performance of staining. We found many (oo)cyst-like objects with typical fluorescence, not (co)cysts, from the Han River water samples, and then it was concluded that nuclei staining by DAPI (4',6-diamidino-2-phenylindole) and examination by Differential Interference Contrast Microscope should be critical for valid identification.

• Korean Journal of Food Science and Technology
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• v.45 no.3
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• pp.325-332
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• 2013

We aimed to determine the quality indicators for quality prediction of frozen green pumpkin in distribution. Freshly harvested green pumpkin slices were blanched under optimal conditions (confirmed in a preliminary experiment), quick-frozen at $-40^{\circ}C$ for 24 h, and stored at 0, -5, -15, and $-25^{\circ}C$. The correlation between each quality characteristic and the sensory preference rate was analyzed. There was a significant correlation between storage temperature-related drip rate and preference rate across all temperatures, except at$-25^{\circ}C$. Hunter values, a and b, showed relatively high correlation coefficient values at -5, -15, and $-25^{\circ}C$. Therefore, a change in the Hunter values should be considered when storing green pumpkin, because of their significant correlation with changes in the sensory preference and drip rates. Furthermore, they should be applied as quality indicators for the quality prediction of frozen green pumpkin in distribution.

• Korean Journal of Poultry Science
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• v.42 no.4
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• pp.307-314
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• 2015

The study was carried out to investigate the effects of by-products of herbal medicines on performance, enteric microflora and blood biochemical profiles and immunological parameters in broiler chicks. A total of ninety-six, 3-d-old birds were assigned to a basal diet (CON) or a basal diet supplemented with 0.15 % (HM1), 0.3% (HM2) or 0.5% (HM3) by-products of herbal medicines. There was a significantly (p<0.05) improved feed conversion ratio (FCR) in birds fed diet supplemented with 0.15% by-products of herbal medicines (HM1) compared with the control birds during starter period (3~21 days). However, no difference in body weight, feed intake, total gain and FCR among treatment groups was observed during the entire feeding period (3~35 days). The colony forming units (CFU) of E. coli and Lactobacilli in the digesta of ileo-cecum was not also affected by dietary treatment. Serum AST (aspartate aminotransferase) and glucose decreased (p<0.05) in birds fed diets supplemented with herbal medicines compared with those fed the basal diet. In particular, the birds fed diets supplemented with herbal medicines showed a significant (p<0.05) increase in blood mean corpuscular volume (MCV) level compared with the control birds. However, the most of blood biochemical and hematological parameters and immunoglobulins (IgG and IgA) were not affected by the dietary treatment. In conclusion, the low level of dietary herbal medicines showed beneficial effects on FCR during starter period and liver functions, suggesting that by-products of herbal medicines may be applicable as functional feed additives in birds.

• Journal of Dairy Science and Biotechnology
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• v.29 no.2
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• pp.37-42
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• 2011

The changes in pH, titratable acidity, chromaticity, total count, coliform group and organoleptic properties of the whole market milks (UHT, LTLT) that sold currently on the domestic market were stored after their production at 0, 10, 20, 30 and $40^{\circ}C$ to predict their quality during distribution, and examined prior to the analysis on the correlation of their quality properties and organoleptic preference level and discovery of optimal quality indicator. The investigation of correlation between pH, acidity and preference level of milks depending on respective storage temperature showed significant correlation (p<0.01) for the milk stored at 10, 20, 30 and $40^{\circ}C$, and the higher temperature was directly proportional to the higher correlation coefficient. The correlation between total count and preference level for LTLT milk stored at 0, 10, 20, 30 and $40^{\circ}C$ showed high correlation coefficient at every high temperature condition respectively as R=0.81, R=0.91, R=0.96, R=0.90 & R=0.99, and the correlation coefficients were also significant level for the UHT milk irrespective of their storage temperature except $0^{\circ}C$. Accordingly, the changes in total colonies turned out to be suitable to be the quality indicator for the quality prediction of the milk on the distribution.

• Journal of Food Hygiene and Safety
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• v.29 no.4
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• pp.268-277
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• 2014

This study assessed microbiological hazards at postharvest stage of dropwort farms (A, B, C, D, E, F, G, H, I) located in 4 different areas in Korea. The samples were assessed for sanitary indication bacteria (total aerobic bacteria, coliform, and Escherichia coli) and pathogenic bacteria (Escherichia coli O157:H7, Listeria monocytogenes, Staphylococcus aureus and Bacillus cereus). Total aerobic bacteria and coliform in 9 dropwort farms were detected at the levels of 0~7.00 and 0~4.25 log CFU/g, mL, of $100cm^2$. In particular, microbial contamination in worker's hand showed higher than cultivation environment factors. Escherichia coli was detected in several farms of soil, irrigation water, washing water and worker's hand and also, dropwort in these farms was contaminated with E. coli (positive reaction). In case of pathogenic bacteria, B. cereus was detected at the highest levels in soil. S. aureus was detected qualitatively from only one sample of dropwort washed by water. E. coli O157:H7 and L. monocytogenes were not detected. Although dropwort pass through 2 process (trimming and washing), the microbial contamination was not differ significantly before and after which indicates that current washing system was not effect on reduction of microorganism. From these results, the postharvest environment and workers have been considered as cross-contamination factors. Thus, processing equipments and personal hygiene should be managed to reduce the microbial contamination of dropwort. Accordingly management system such as good agricultural practices (GAP) criteria is needed for the safety of dropwort

• Microbiology and Biotechnology Letters
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• v.18 no.5
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• pp.484-489
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• 1990

An intracellular inulase ( fJ-fructofuranoside fructohydrolase, EC 3.2.1.26) from Bacillus subtilis has been partially purified and its mode of action and general properties were studied. The enzyme had an apparent molecular weight of 49,000 as estimated by gel filtration and its pI point was 5.2. Substrate concentration studies showed an apparent Km of 10 mM for sucrose and of 18 mM for raffinose. The enzyme was an acid-labile protein with a pH optimum of 6.6. The optimum temperature was 50$^{\circ}$C. The enzyme acts on straight chain oligo- and poly-fructosides of the inulin series via a exo-wise cleavage mechanism, as well as on sucrose.

• Korean Journal of Microbiology
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• v.27 no.3
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• pp.221-224
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• 1989

Amylolytic filamentous fungus, Aspergillus oryzae and nonamylolytic sugar fermentable yeast, Saccharomyces cerevisiae were fused by protoplast fusion in order to develope microorganisms having their intergrated function. Aminoacid auxotrophic properties were used as a genetic marker of protoplast fusion, and 35% PEG 4000 was used as a fusogenic agent. Complementation frequengy of fusion was $4.6\times 10^{-6}$ Obtained fusants showed the morphology of yeast strains, the amylase activity and the ethanol productivity. Among the properties of the fusants, morphology and prototrophic property were sustained stably but their ethanol productivity from starch was reduced. Although fusant strains had 0.5-fold ethanol productivity compared to that of S. cerevisiae in glucose medium, they produced ethanol from strach by direct fermentation.

• Proceedings of the Korean Society for Applied Microbiology Conference
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• 1979.10a
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• pp.234-236
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• 1979

인구의 도시집중과 고도산업사회 건설에 필연적으로 수반되는 도시하수 및 산업폐수등은 하천을 심각하게 오염시켜 하천수가 지니고 있는 자정능력 한계를 초과하고 있어 재생될수 없는 상태이므로 수자원의 보호가 요청된다. 이런 상황의 하천오염 증가 추세와 주요 오염원 및 오염물에 대하여 고찰하고 대책에 방향을 제시한다. 먼저 전국의 급수 현황과 장래를 보면 다음과 같다. 한편 수도권 한강수계를 오염시키는 주요 오염원인 폐수를 보면 주거지의 생활하수, 상업행위로 발생되는 폐수와 공장의 산업폐수로 대별할 수 있으며 수도권 한강에 유입 되는 지천 수질을 보면 다음과 같다. 위와 같은 상태의 총폐수량은 280만톤인데 비하여 청계, 중량하수처리장과 서부 북부 동부분뇨처리장의 일일 처리능력은 16.4%에 불과하다. 한편 서울지역 오염원구성비를 보면 다음과 같다. 이런 계속적인 오염물은 1977년 경우 갈수기에 80~100t/sec의 하천유량으로 희석되고 있어 자정능력 한계를 벗어나서 하류의 물은 혼탁하고 용존산소의 고갈현상을 초래하고 있다. 그러므로 도시 하천에서는 수류침체로 인한 하상퇴적을 방지하여 국소적 오염의 심화를 방지하며 유량을 증가 시켜야 한다. 수도권 한강 수계의 수질의 일부는 다음과 같다. 한편 생활수준의 향상과 더불어 수요가 급증되며 처리장의 효율과 하천수의 수질을 악화시키는 합성세제의 총생산량은 1971년에 21000톤이던 것이 1978년에는 약 50,000톤에 이르고 있으며 이중 55~60%가 서울지역에서 소모되는 것으로 추산되어 진다' 결과 한강수에서 검출되는 합성세제의 오염 현황을 보면 다음과 같이 이미 몇개 지점에서는 세계 보건기구의 허용량인 0.5ppm을 초과 하고 있는 실정이다. 또한 오염의 연쇄현상을 나타내는 중금속의 일종인 csduium의 검출 정도를 보면 다음과 같다. 이상의 하천오염에 따른 수중생태계의 변화는 물리적 화학적 생물학적 환경요인이 복합적으로 작용하는 세부적 기계에 대하여는 규명되지 않은 문제가 아직도 많으며 지표생물의 표현형은 중요한 가치를 부여하고 있다. 식물성 plankton의 우점종의 출현 빈도에 따른 수질계급을 보면 뚝섬지역 BOD 3.3~5.3 빈부수성 $~\alpha$ 중부수성, 보광동 BOD 6.0~10.3중부수성, 제 2한강교 BOD10~28 $\alpha$ 강부수성, 난지도 BOD29 $\beta$ 강부수성 등이며 이와 상이한 결과도 보여주고 있다. 이상으로 볼 때 1) 가정하수의 질을 높이기 위하여 분뇨정화조 의 효율증대 2) 산업폐수의 공정별 폐수량의 조절 및 폐수성 상에 따른 총량규제에 대비한 효율증대 3) 하천의 오염부하와 자정능력 최대한 부여 4) 폐수처리를 위한 미생물제개발 및 오염지표 종 연구와 오염내성 생물의 연구등이 종합적 으로 수행되어야 한다. 5) 이상의 모든 조사와 연구결과를 객관적으로 표기할 수 있도록 하천의 이정표가 정해져야 하겠다.