• 한국토양비료학회지
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• 제45권6호
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• pp.1073-1085
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• 2012

Soil microbial communities are immensely diverse and complex with respect to species richness and community size. These communities play essential roles in agricultural soil because they are responsible for most of the nutrient cycles in the soil and influence the plant diversity and productivity. However, the majority of these microbes remain uncharacterized because of poor culturability. Next-generation sequencing techniques have revolutionized many areas of biology by providing cheaper and faster alternatives to Sanger sequencing. Among them, amplicon pyrosequencing is a powerful tool developed by 454 Life Sciences for assessing the diversity of complex microbial communities by sequencing PCR products or amplicons. This review summarizes the current opinions in amplicon sequencing of soil microbial communities, and provides practical guidance and advice on sequence quality control, aligning, clustering, OTU- and taxon-based analysis. The last section of this article includes a few representative studies conducted using amplicon pyrosequencing.

• Preventive Nutrition and Food Science
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• 제16권4호
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• pp.364-369
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• 2011

Levels of carbon dioxide gas, a metabolite of microbial growth, have been reported to parallel the onset of microbial spoilage and may be used as a convenient index for a packaged food's shelf life. This study aimed to establish a kinetic model of $CO_2$ production from perishable food for the potential use for shelf life control in the food supply chain. Aerobic bacterial count and package $CO_2$ concentration were measured during the storage of seasoned pork meat at four temperatures (0, 5, 10 and $15^{\circ}C$), and their interrelationship was investigated to establish a mathematical model. The microbial growth at constant temperature was described by using model of Baranyi and Roberts. $CO_2$ production from the stored food could be explained by taking care of its yield and maintenance factors linked to the microbial growth. By establishing the temperature dependence of the microbial growth and $CO_2$ yield factor, $CO_2$ partial pressure or concentration in package headspace could be estimated to a limited extent, which is helpful for controlling the shelf life under constant and dynamic temperature conditions. Application and efficacy of the model needs to be improved with further refinement in the model.

• 한국환경농학회지
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• 제20권5호
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• pp.325-329
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• 2001

Soil enzyme and microbial activities are affected by fertilizer and compost applications and can be used as sensitive indicators of ecological stability. Microbial population and soil enzymes viz., dehydrogenase, urease, acid phosphatase and aryl-sulphatase were determined in the long-term fertilizer and compost applied paddy soil. Soil samples were collected from the four treatments (control, compost, NPK and compost+NPK). Long-term NPK+compost application significantly increased activities of urease, dehydrogenase and acid phosphatase than all other treatments. The compost application enhanced activities of urease, dehydrogenase and acid phosphatase than the NPK application. However, arylsulfatase activity was not significantly different between compost and fertilizer application. The highest microbial population was recorded in the NPK+compost treatment. The compost application also resulted in higher microbial population than the NPK application. The above results indicate that ecological stability could be maintained by application of compost alone or with NPK.

• Corrosion Science and Technology
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• 제7권1호
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• pp.27-34
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• 2008

In industrial and fluid handling systems, frequently the protective film forming materials suffer from severe corrosion due to microbial effects. As an example, various micro-organisms, including bacteria, exist in seawater normally fed to power and desalination plants. Unless seawater intakes are properly disinfected to control these microbial organisms, biological fouling and microbial induced corrosion (MIC) will be developed. This problem could destroy metallic alloys used for plant construction. Seawater intakes of cogeneration plants are usually disinfected by chlorine gas or sodium hypochlorite solution. The dose of disinfectant is designed according to the level of contamination of the open seawater in the vicinity of the plant intake. Higher temperature levels, lower pH, reduced flow velocity and oxidation potential play an important role in the enhancement of microbial induced corrosion and bio-fouling. This paper describes, in brief, the different types of bacteria, mechanisms of microbiological induced corrosion, susceptibility of different metal alloys to MIC and possible solutions for mitigating this problem in industry. A case study is presented for the power plant steam condenser at Al-Taweelah B-station in Abu Dhabi. The study demonstrates resistance of Titanium tubes to MIC.

• 상하수도학회지
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• 제16권6호
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• pp.679-685
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• 2002

The objective of this study was investigated for the microbial community structure and treatment performance of domestic wastewater in lab-scale submerged membrane bioreactor operated with anoxic-oxic cycles. Respiratory quinone profiles were applied as tools for identifying different bacterial populations. The cycle time program of bioreactor was control under anoxic/oxic of 60/90 minutes with an hydraulic retention time of 8.4 hrs. The average $COD_{Cr}$ removal efficiency of domestic wastewater was as high as 93%. The results showed complete nitrification of $NH_4^+$-N generated during oxic period and up to 50% of the total nitrogen could be denitrified. The dominant quinone types of suspended microorganisms in bioreactor were ubiquinone (UQ)-8, -10, followed by menaquinone (MK)-6, and MK-7 for anoxic period, but those for oxic period were UQ-8, MK-6, followed by UQ-10 and MK-7. The microbial diversities of bioreactor at anoxic and oxic periods, calculated based on the composition of all quinones were 10.4 and 12.2-11.8, respectively. The experimental results showed that the microbial community structure in the submerged membrane bioreactor treating domestic wastewater was slightly affected by intermittent aeration.

• 한국산업보건학회지
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• 제15권3호
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• pp.270-276
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• 2005

This study was conducted to examine whether a specific synthetic metalworking fluid (MWF), "A", in use for 10 months without replacement, displayed microbial resistance and to identify the additives associated with the control of microbial growth. Three synthetic MWF products ("A", "B", and "C") were studied every week for two months. Microbial deterioration of the fluids was assessed through evaluation by endotoxin, bacteria and fungi levels in the MWFs. In addition, formaldehyde, boron, ethanolamine, and copper levels were also studied to determine whether they influence microbial growth in water-based MWFs. Throughout the entire study in the sump where MWF "A" was used, bacteria counts were lower than 103 CFU/mL, and endotoxins never exceeded 103 EU/mL. These levels were significantly lower than levels observed in sumps badly deteriorated with microbes. Boron levels in MWF "A" ranged from 91.7 to 129.6 ppm, which was significantly higher than boron levels found in other MWF products. The total level of ethanolamine (EA) in MWF "A" ranged from 35,595 to 57,857 ppm (average 40,903 ppm), which was over ten times higher than that found in other MWFs. Monoethanolamine (MEA), diethanolamine (DEA) and triethanolamine (TEA) concentrations in MWF "A" were also significantly higher than seen in other MWFs. However, although EA and boron might improve anti-microbial performance, their abuse can pose a serious risk to workers who handle MWFs. From an industrial hygiene perspective, our study results stress that the positive synergistic effect of boron and EA in reducing microbial activity in MWF must be balanced with the potentially negative health effects of such additives. Our study also addresses the disadvantage of failing to comprehensively report MWF additives on Material Safety Data Sheets (MSDS). Future research in MWF formulation is needed to find the best level of EA and boron for achieving optimal synergistic anti-microbial effects while minimizing employee health hazards.

• Journal of Microbiology and Biotechnology
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• 제26권1호
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• pp.110-119
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• 2016

High-solid anaerobic digestion of sewage sludge achieves highly efficient volatile solid reduction, and production of volatile fatty acid (VFA) and methane compared with conventional low-solid anaerobic digestion. In this study, the potential mechanisms of the better performance in high-solid anaerobic digestion of sewage sludge were investigated by using 454 high-throughput pyrosequencing and real-time PCR to analyze the microbial characteristics in sewage sludge fermentation reactors. The results obtained by 454 highthroughput pyrosequencing revealed that the phyla Chloroflexi, Bacteroidetes, and Firmicutes were the dominant functional microorganisms in high-solid and low-solid anaerobic systems. Meanwhile, the real-time PCR assays showed that high-solid anaerobic digestion significantly increased the number of total bacteria, which enhanced the hydrolysis and acidification of sewage sludge. Further study indicated that the number of total archaea (dominated by Methanosarcina) in a high-solid anaerobic fermentation reactor was also higher than that in a low-solid reactor, resulting in higher VFA consumption and methane production. Hence, the increased key bacteria and methanogenic archaea involved in sewage sludge hydrolysis, acidification, and methanogenesis resulted in the better performance of high-solid anaerobic sewage sludge fermentation.

• 한국축산식품학회지
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• 제36권5호
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• pp.617-625
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• 2016

Pastırma, a dry-cured meat product, is produced from the whole muscle and/or muscles obtained from certain parts of beef and water buffalo carcasses. The purpose of this study was to determine the effects of different levels of sodium nitrite on changes in the physicochemical and microbial quality during the production of pastırma. The changes in residual nitrite, salt, pH, moisture, thiobarbutiric acid reactive substances (TBARS), colour (L*, a*, b*), total aerobic mesophilic bacteria (TAMB), lactic acid bacteria (LAB), Micrococcus/Staphylococcus (M/S), mould-yeast (M-Y), and Enterobacteriaceae counts of pastırma with 0, 50, 100 and 150 ppm sodium nitrite were determined during the production. The nitrite levels and the production stages had significant effects (p<0.01) on residual nitrite, TBARS, pH, salt, and colour values. The TBARS values of the pastırma with nitrite were significantly lower (p<0.05) than the control. The final TAMB, LAB, M/S, and M-Y counts of pastırma with 150 ppm nitrite were significantly (p<0.05) lower than the control. Also, the a* (relative redness) values of control pastırma were significantly lower (p<0.05) than the pastırma with nitrite. The production stages had a significant effect (p<0.01) on the moisture.

• 생물환경조절학회지
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• 제19권4호
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• pp.343-350
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• 2010

본 연구는 수확시기와 같은 수확 전 요인이 수확 후 신선편이 결구상추의 품질과 미생물 수에 미치는 영향을 구명하기 위하여 수행하였다. 신선편이 가공업체에서 사용하는 결구상추를 5, 6, 7, 10, 12월에 수확하여 관행적인 방법으로 가공한 뒤 필름에 포장하고 $5^{\circ}C$에서 9일 동안 저장하면서 품질 조사를 하였다. 미생물 측정을 위한 샘플은 각 단계별(수확, 수송, 가공전, 절단, 1차-세척, 2차-세척, 저장 후 3, 6, 9일)로 수집되었다. 실험 결과 하우스에서 재배되어 5, 10월에 수확된 결구상추는 신선편이 가공 후 포장백 내부의 $O_2$ 농도가 낮고 $CO_2$는 매우 높았으며, 제품의 전해질 누출이 높게 나타났다. 반면 노지에서 재배된 6, 7월 수확 및 겨울철 하우스재배인 12월에 수확한 원료 는 비교적 낮은 $CO_2$, 전해질 누출 및 갈변을 나타내었다. 원료상태의 미생물수는 7월(6.76 log)에 가장 높았고, 신선편이 가공 후 저장중의 미생물 증식은 5월 시료에서 가장 높게 나타났다. 이상의 결과로부터 신선편이 결구상추를 고온, 저습조건의 노지에서 재배되어 6월 상순에 수확한 원료를 사용한 경우 품질과 미생물적 안전성이 모두 우수하였다. 반면, 하우스에서 재배되어 10월에 수확한 결구상추를 원료로 사용한 경우 가공 전과 후의 미생물적 안전성은 모두 우수하였으나, 이취가 빨리 발생하여 품질특성이 나쁘게 나타났다. 따라서 연중 고품질의 신선편이 결구상추 생산을 위해서는 품질과 안전성을 동시에 제어하고 원료의 환경에 따른 품질유지 기간을 달리 설정할 필요가 있는 것으로 생각된다.

• 한국식품위생안전성학회지
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• 제32권4호
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• pp.306-313
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• 2017

본 연구는 농산물의 미생물학적 수준에 관하여 체계적인 연구분석(systemic analysis) 기법을 이용하여 비가열 농산물의 위생안전관리를 목적으로 연구를 수행하였다. 2001년부터 2015년까지 인쇄된 관련 연구논문을 NDSL 검색엔진을 활용하여 자료를 수집, 리뷰, 자료 정리, 분석 및 결과 정리하였다. 농산물 분류체계를 비교 조사하여 미국의 IFSAC (Interagency Food Safety Analytics Collaboration)의 식품분류체계에 따라 국내 농산물을 분류하였다. 선정된 22건의 논문 내 89건의 데이터를 종합한 결과, 분류체계 내에서 국내 농산물에서 총균수 수준이 높고 대장균 오염이 가장 많은 농산물은 엽경채류와 새싹 발아채소(sprouts)로 나타났다. 단체급식에서 생채소로 소비되는 엽경채류에서 단체급식의 다소비 농산물로서 식중독과 연관성이 높은 품목인 상추, 부추, 배추에 관하여 미생물에 관한 자료 검색, 수집, 선정 및 분석 결과 최종 33편의 논문에서 미생물의 정량적 수준은 총균수 4.15~ 7.69 log CFU/g, 대장균군 1~6.99 log CFU/g, B. cereus 0.51~3.9 log CFU/g으로 나타났다. GAP 데이터 기반 농산물의 미생물학적 영향을 미치는 환경인자 문헌조사 결과 퇴비, 토양, 작업자 손, 장갑이 주요 영향인자로 나타났다. 농산물의 미생물학적 관리를 위하여 전문가 의견과 문헌조사를 통하여 GAP도입, 취약 품목의 미생물학적 분석계획, 토양으로부터 작물의 오염을 최소화 할 수 있는 작물생산방식 도입 및 실행규범 준수가 필요하다.