• Journal of Food Hygiene and Safety
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• v.27 no.3
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• pp.301-305
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• 2012

This study was conducted to investigate the microbiological contamination levels in rice cakes and rice flour due to climate change in three areas classified to their temperature and precipitation. We investigated the contamination levels of total aerobic bacteria, coliforms, Escherichia coli, Bacillus cereus, Staphylococcus aureus, Clostridium perfringens of rice flour and 3 rice cakes such as Garaetteok, Sirutteok and Gyeongdan. Contamination levels of total aerobic bacteria in rice flour were 4.9 log CFU/g. In a total of 70 rice flour, yeasts & molds and coliforms were detected in 42 and 52 samples at the levels of 43 CFU/g and 1.29 log CFU/g, respectively. S. aureus were detected in only 1 rice flour (1.66 log CFU/g) out of 70. In an investigation of contamination levels in rice cakes, the population of total aerobic bacteria were highest in Gyeongdan (5.18 log CFU/g) and coliforms were highest in Gareattock (2.93 log CFU/g). There was no detection of E. coli and B. cereus except for only 1 Gareattock (1.20 log CFU/g). There were no differences of contamination levels among the three areas. If constant monitoring of rice cakes and rice flour is conducted on the basis of this study, it is expected to be able to analyze the change of contamination levels in rice cakes and rice flour due to climate change.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.5
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• pp.839-846
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• 2016

Since oil leakage is one of the most common nonpoint pollution sources that contaminate soil in Korea, the capacity of soil microbial community for degrading petroleum hydrocarbons should be considered to assess the functional value of soil resource. However, conventional methods (e.g., microcosm experiments) to assess the remediation capacity of soil microbial community are costly and time-consuming to cover large area. The present study suggests a new approach to assess the toluene remediation capacity of soil microbial community using a microbial diversity index, which is a simpler detection method than measuring degradation rate. The results showed that Shannon index of microbial community were correlated with specific degradation rate ($V_{max}$), a degradation factor. Subsequently, a correlation equation was generated and applied to Michaelis-Menten kinetics. These results will be useful to conveniently assess the remediation capacity of soil microbial community and can be widely applied to diverse engineering fields including environment-friendly construction engineering fields.

• Korean Journal of Soil Science and Fertilizer
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• v.30 no.2
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• pp.200-207
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• 1997

In order to evaluate the soil microbiological characteristics of paddy fields in Korea, surface soils were sampled from 63 sites in different agroclimatic zones before submersion of the fields. The distribution of microorganisms and the microbial diversity indices were examined. Soil microbial populations were generally higher in southern area than in northern area. The colony forming units(cfus) of fluorescence Pseudomonas sp. showed the greatest regional differences, among the microbes investigated. On the topographical differences, the cfus of aerobic bacteria, fluorescence Pseudomonas sp. and Azotobacter sp. maintained high level in coastal plains; and on the sail textural difference, fungus was the highest in clay soil, but Bacillus sp., Azotobacter sp and denitrifiers were the highest in silty clay loam soil at 0.05 probability level based on the multiple range test. The numbers of ammonium oxidizers and Azotobacter sp. were increased with soil pH. Microbial diversity indices of paddy fields which calculated from the percentages of Bacillus sp. fluorescence Pseudomonas sp. Azotobacter sp. denitrifiers, ammonium oxidizers, nitrite oxidizers, actinomycetes and fungus to these total microbial numbers were between 0.109 and 0.661. On the soil textures, the microbial diversity indices of sandy, sandy loam, silty clay loam, clay loam and clay soil were 0.443, 0.427, 0.414, 0.405 and 0.362 respectively.

• Economic and Environmental Geology
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• v.53 no.6
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• pp.655-666
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• 2020

This study evaluated the characteristics of arsenic production in groundwater through microbial community analysis of groundwater contaminated with high arsenic in Haman area. Groundwater in Haman area is contaminated with arsenic in the range of 0-757.2 ㎍/L, which represents the highest arsenic contamination concentration reported in Korea as natural groundwater pollution source. Of the total 200 samples, 29 samples (14.5%) showed higher arsenic concentration than that of 10 ㎍/L, which is the standard for drinking water quality, and 8 samples (4%) found in wells with 80-100 m depth were above 50 ㎍/L. In addition, seven wells with arsenic concentration more than 100 ㎍/L located in the northern part of Haman. As a result of microbial community analysis for high arsenic-contaminated groundwater, the microbial community compositions were significantly different between each sample, and Proteobacteria was the most dominant phyla with an average of 61.5%. At the genus level, the Gallinonella genus was predominant with about 12.8% proportion, followed by the Acinetobacter and Methermicoccus genus with about 7.8 and 7.3%, respectively. It is expected that high arsenic groundwater in the study area was caused by a complex reaction of geochemical characteristics and biogeochemical processes. Therefore, it is expected that the constructed information on geochemical characteristics and microbial communities through this study could be used to identify the origin of high arsenic groundwater and the development of its controlling technology.

• Food Engineering Progress
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• v.22 no.4
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• pp.386-391
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• 2018

Effects of a commercial scale intervention system combining ultraviolet (UV)-C and plasma treatments on the microbial decontamination of black pepper powder were investigated. The process parameters include treatment time, time for plasma accumulation before treatment, and water activity of black pepper powder. A significant reduction in the number of indigenous aerobic mesophilic bacteria in black pepper powder was observed after treatments lasted for ${\geq}20min$ (p<0.05) and the reduction was differed by powder manufacturer. The microbial reduction rates obtained by individual UV-C treatment, individual plasma treatment, and UV-C/plasma-combined treatment were 0.2, 0.5, and 1.0 log CFU/g, respectively, suggesting that the efficacy of the microbial inactivation was enhanced by treatment combination. Nonetheless, neither plasma accumulation time nor powder water activity affected the microbial inactivation efficacy of the combined treatment. The UV-C/plasma-combined treatment, however, decreased lightness of black pepper powder, and the decrease generally increased as operation time increased. The plasma accumulation time of 20 min resulted in significant reduction in both lightness and brown color. The results indicate that the commercial-scale intervention system combining treatments of UV-C and plasma has the potential to be applied in the food industry for decontaminating black pepper powder.

• Korean Journal of Soil Science and Fertilizer
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• v.31 no.2
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• pp.197-203
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• 1998

Although biological metabolism in soil is very important for evaluating the soil properties, most of researches have concerned mainly about physical and chemical sides. In this study, biological characteristics were examined to demonstrate the biota in the plastic film house soils. Contents of organic matter and phosphate in soil were increased with cultivation period. ECs of soil cultivated spinach and melon were $3.59dS\;m^{-1}$ and $3.46dS\;m^{-1}$ respectively: these values were higher than that of rose and flower, which were $1.23dS\;m^{-1}$ and $1.32dS\;m^{-1}$ respectively. The population of fluorescent Pseudomonas strains of the soil cultivated flowers: $113.8{\times}10^4{\sim}129.7{\times}10^4cfu\;g^{-1}$ was higher than that of leafy vegetables: $40.7{\times}10^4{\sim}97.9{\times}10^4cfu\;g^{-1}$ and fruiting vegetables: $25.0{\times}10^4{\sim}91.7{\times}10^4cfu\;g^{-1}$. However the number of Fusarium strains of the soil cultivated with flowers: $3.8{\times}10^2{\sim}4.0{\times}10^2cfu\;g^{-1}$ was lower than that of leafy vegetables: $4.3{\times}10^2{\sim}16.3{\times}10^2cfu\;g^{-1}$ and fruiting vegetables: $7.6{\times}10^2{\sim}30.0{\times}10^2cfu\;g^{-1}$. In relation to the cultivation period, the habitation density of aerobic bacteria, mesophilic Bacillus, thermophilic Bacillus, and fluorescent Pseudomonas strains was the highest in the soil cultivated over 11 years, but diversity index showed negative correlation with cultivation period. Microbial biomass C in these soils had positive correlation with each number of microorganisms including aerobic bacteria, actinomycetes, and strains of mesophilic Bacillus as well as the total number of these microorganisms.

• Food Science and Preservation
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• v.24 no.1
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• pp.36-43
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• 2017

The aim of this study was to provide the quality index of salted Korean cabbage in a short-term distribution system. Salted Korean cabbages were packaged with or without 2% salt water, and then distributed in a conventional system (CVS) and a cold-chain system (CCS) for 6 h. The material temperature of samples with and without salt water gradually increased to $19.57^{\circ}C$ and $19.43^{\circ}C$ in a CVS, respectively and to $10.73^{\circ}C$ and $12.90^{\circ}C$ in a CCS, respectively. Salinity of the materials in a CCS did not change, whereas salinities of the materials in a CVS were 1.2 and 1.7 fold higher, respectively. Also, a slight increase in acidity was observed in both packaging materials in a CCS. In the case of a CVS, total aerobic bacteria and lactic acid bacteria increased to 7.62 log CFU/g and 6.77 log CFU/g in the materials with salt water, respectively, whereas the number of total aerobic bacteria and lactic acid bacteria ranged between 5.62-5.85 log CFU/g and 4.33-4.83 log CFU/g in the materials without salt water, respectively. However, significant microbial changes were not observed in a CCS as distribution time increased. CCS with salt water packaging was effective in achieving microbial control and maintaining physicochemical quality. Salinity, aerobic bacteria, and lactic acid bacteria can be useful as quality indices for a CVS, and acidity can be useful as quality index for a CCS.

• Korean Journal of Ecology and Environment
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• v.37 no.3 s.108
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• pp.344-354
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• 2004

A pilot study was performed from September 2000 to April 2004 to examine the feasibility of the wetland-pond system for the agricultural reuse of reclaimed water. The wetland system was a subsurface flow type, with a hydraulic residence time of 3.5 days, and the subsequent pond was 8 $m^3$ in volume (2 m ${\times}$ 2 m ${\times}$ 2 m) and operated with intermittent-discharge and continuous flow types. The wetland system was effective in treating the sewage; median removal efficiencies of $BOD_5$ and TSS were above 70.0%, with mean effluent concentrations of 27.1 and 16.8 mg $L^{-1}$, respectively, for these constituents. However, they did often exceed the effluent water quality standards of 20 mg $L^{-1}$. Removal of T-N and T-P was relatively less effective and mean effluent concentrations were approximately 103.2 and 7.2 mg $L^{-1}$, respectively. The wetland system demonstrated high removal rate (92 ${\sim}$ 90%) of microorganisms, but effluent concentrations were in the range of 300 ${\sim}$ 16,000 MPN 100 $mL^{-1}$ which is still high for agricultural reuse. The subsequent pond system provided further treatment of the wetland effluent, and especially additional microorganisms removal in addition to wetland-pond system could reduce the mean concentration to 1,000 MPN 100 $mL^{-1}$ from about $10^5$ MPN 100 $mL^{-1}$ of wetland influent. Other parameters in the pond system showed seasonal variation, and the upper layer of the pond water column became remarkably clear immediately after ice melt. Overall, the wetland system was found to be adequate for treating sewage with stable removal efficiency, and the subsequent pond was effective for further polishing. This study concerned agricultural reuse of reclaimed water using natural systems. Considering stable performance and effective removal of bacterial indicators as well as other water quality parameters, low maintenance, and cost-effectiveness, wetland- pond system was thought to be an effective and feasible alternative for agricultural reuse of reclaimed water in rural area.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2011.03a
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• pp.110-110
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• 2011

염색공업 폐수는 그 성분이 일반적으로 매우 복잡하며, 작업공정의 가동 사항에 따라 수질 변동이 큰것이 특징으로, 각 공정에서 배출되는 염료, 보조화학물질, PVA(Polyvinyl alchol), 전분, wax 등이 포함되어 있으며 pH가 높고, 색도로 인해 하천에 방류될 경우 확산성이 높아 미생물에 의한 자정작용을 방해하여 하천의 수중생태계를 파괴할 우려가 있다. 이러한 염색산업에서 발생하는 폐수는 일반적으로 응집침전, 부상분리법 등의 전처리한 후 활성오니공정으로 처리하는 방법이 널리 이용되고 있으나, 이들 처리공정으로는 폐수 속에 포함되어 있는 다양한화학적 구조의 색소성분 및 유해물질을 완벽하게 제거하는 것이 어려운 실정이다. 유기물 함량이 높은 염색폐수를 처리하기 위해 제안된 기술로는 산소활성슬러지법, 유동상 및 고정상 생물막법, 포괄고정화법 등이 있다. 이러한 기술들중 기존의 처리공정을 증축없이도 처리효율을 높일 수 있는 방법으로 담체를 이용한 부유메디아 생물막공정(Moving-Bed BioReactor, MBBR)이 있다. 이공정은 미생물이 부착, 성장할 수 있는 공극율과 비표면적이 큰 담체를 이용하므로 반응조내의 부유 미생물 뿐만 아니라 담체에 고농도로 부착된 부착 미생물에 의해서도 유기물을 제거하기 때문에 다른 공정들에 비해 처리효율이 뛰어나고 기존의 활성슬러지 공정에 비해 갑작스러운 부하변동 및 유독성 폐수유입에 대해서도 안정적으로 운전이 가능한 장점이 있다. 본연구에서는 부유메디아 생물반응기(Moving-Bed BioReactor, MBBR)을 이용하여 염색폐수내 $COD_{Mn}$, 색도 및 난분해성 물질인 PVA 저감에 대한 Lab-scale test 수행하였다. 실험에 사용된 염색폐수의 수질은 평균 pH 13, $COD_{Mn}$ 900 mg/L, SS 135 mg/L, 색도 1,134 [C.U.], PVA 593 mg/L였으며, 2L의 반응기를 사용하여 회분식 실험을 수행였다. 본 실험에서는 호기성 미생물에 의한 염색폐수의 생분해가 유지되는데 필요한 최적의 용존산소 농도와 이에 필요한 공기 폭기량을 결정하기 위하여 i) DO uptake rate측정과 ii) 담체의 충진율, iii) COD/N ratio, iv) Air 유량, v) 담체내 흡착제의 종류, vi) $Ca^{2+}$ 첨가가 염색폐수의 생분해에 미치는 영향을 살펴보았다. 운전시간을 7일로 하여 COD, 색도, PVA 등을 측정한 결과 담체를 첨가한 경우가 담체를 첨가하지 않은 경우 보다 제거효율이 뛰어났다. 특히 충진율 30%(C/N 3)의 경우에서 COD, 색도, PVA의 제거율이 각각 평균 65%, 70%, 60%로 가장 높은 제거효율을 나타내었다.

• Korean Journal of Food Science and Technology
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• v.31 no.1
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• pp.212-218
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• 1999

The effects of gamma irradiation (1, 3 and 5 kGy) and packaging methods (air and vacuum) on the growth of microorganisms contaminated in beef was investigated during storage at different temperatures (-20, 4 and $25^{\circ}C$). The initial microbial population of beef was $8.0{\sim}10^2\;CFU/g$ in total aerobic bacteria, $2.0{\times}10^2\;CFU/g$ in total lactic acid bacteria, $8.0{\times}10^1\;CFU/g$ in molds, $6.0{\times}10^2\;CFU/g$ in Pseudomonas sp. and $7.0{\times}10^2\;CFU/g$ in coliforms, respectively. Gamma irradiation at 5 kGy completely eliminated pathogenic bacteria in beef. Gamma irradiation at such dose and subsequent storage at less than $4^{\circ}C$ could ensure hygienic quality prolong the microbiological shelf-life resulting from the reduction of spoilage microorganisms. The different packaging methods of beef caused negligible changes in the growth of microorganisms during storage.