• 생명과학회지
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• 제17권12호
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• pp.1616-1621
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• 2007

발효된 오이의 산패는 원하지 않는 미생물의 2차적 생장에 의한 결과이며 장기보관을 원하는 발효오이 식품은 일반적으로 고농도의 염을 사용한다. 염의 농도를 최소한으로 하면서 산패를 방지할 수 있는 pH의 범위를 모색하기 위하여 다양한 조합의 pH와 NaCl 농도를 갖는 발효오이즙(FCS) 배양액에 3가지 종류의 산패액을 각각 접종하여 발효오이의 산패여부를 조사하였다. pH3에서는 NaCl의 첨가가 없더라도 산패는 일어나지 않는데 비하여 pH 5.0에서는 4%의 NaCl에서도 모두 산패가 진행되었다. pH 3.5, pH 4, pH 4.5 에서는 0%와 2% NaCl의 범위 내에서 다양한 결과를 보였다. 이 결과를 바탕으로 발효오이의 산패를 예견할 수 있는 조견표를 작성하였다. 조견표의 사용은 발효오이의 장기보관을 위한 적절한 산도와 염의 농도의 선택을 가능하게 할 것이다.

• Journal of Microbiology and Biotechnology
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• 제30권8호
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• pp.1227-1234
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• 2020

In this study, yeast cell immobilization was carried out in a packed bed reactor (PBR) to investigate the effects of the volumetric capacity of carriers as well as the different fermentation modes on fuel ethanol production. An optimal volumetric capacity of 10 g/l was found to obtain a high cell concentration. The productivity of immobilized cell fermentation was 16% higher than that of suspended-cell fermentation in batch and it reached a higher value of 4.28 g/l/h in repeated batches. Additionally, using this method, the ethanol yield (95.88%) was found to be higher than that of other tested methods due to low concentrations of residual sugars and free cells. Continuous ethanol production using four bioreactors showed a higher productivity (9.57 g/l/h) and yield (96.96%) with an ethanol concentration of 104.65 g/l obtained from 219.42 g/l of initial total sugar at a dilution rate of 0.092 h^-1. Furthermore, we reversed the substrate-feed flow directions in the in-series bioreactors to keep the cells at their highest activity and to extend the length of continuous fermentation. Our study demonstrates an effective method of ethanol production with a new immobilized approach, and that by switching the flow directions, traditional continuous fermentation can be greatly improved, which could have practical and broad implications in industrial applications.

• BMB Reports
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• 제48권4호
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• pp.209-216
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• 2015

Stress is now recognized as a universal premorbid factor associated with many risk factors of various chronic diseases. Acute stress may induce an individual's adaptive response to environmental demands. However, chronic, excessive stress causes cumulative negative impacts on health outcomes through "allostatic load". Thus, monitoring the quantified levels of long-term stress mediators would provide a timely opportunity for prevention or earlier intervention of stressrelated chronic illnesses. Although either acute or chronic stress could be quantified through measurement of changes in physiological parameters such as heart rate, blood pressure, and levels of various metabolic hormones, it is still elusive to interpret whether the changes in circulating levels of stress mediators such as cortisol can reflect the acute, chronic, or diurnal variations. Both serum and salivary cortisol levels reveal acute changes at a single point in time, but the overall long-term systemic cortisol exposure is difficult to evaluate due to circadian variations and its protein-binding capacity. Scalp hair has a fairy predictable growth rate of approximately 1 cm/month, and the most 1 cm segment approximates the last month's cortisol production as the mean value. The analysis of cortisol in hair is a highly promising technique for the retrospective assessment of chronic stress. [BMB Reports 2015; 48(4): 209-216]

• 한국식품과학회지
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• 제50권1호
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• pp.44-54
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• 2018

본 연구에서는 김치의 최적 발효 온도 및 기간을 도출하고 도출된 최적 발효 온도와 기간으로부터 김치냉장고 발효 보관 모드를 개발하여, 이 신규 모드가 적용된 김치냉장고 조건에서 보관된 김치가 일반보관 모드에서 보관된 김치시료보다 차별화된 맛과 품질을 나타냄을 검증하고자 하였다. 김치 발효 온도 설정을 위해 김치내 Leuconostoc속이 Lactobacillus속보다 같은 온도에서 보다 생육증가율이 높은 온도 구간을 조사하였을 때 5, 10, $15^{\circ}C$ 구간 중 $5^{\circ}C$ 부근에서 Leuconostoc속의 생육증가율이 Lactobacillus속의 생육증가율보다 가장 높게 (5.3배) 나타났다. 이후 5, 6, $7^{\circ}C$에서 김치발효를 수행하면서 이에 따른 김치의 pH, 산도, 총유산균수, 총유산균 중 Leuconostoc속의 수, 관능평가 등으로 최적 김치 발효 온도 및 발효 기간을 도출하였다. 이로부터 최적 김치 발효 온도는 $6^{\circ}C$임을 알 수 있었다. 김치의 최적 발효일(발효종료일=유산균수 $10^8-10^9CFU/mL$+산도 약 0.40%)에 도달하는데 겨울철에는 약 4-7일, 봄 가을에는 약 3-5일이 소요되었다. 이에 따라 김치 발효 보관 모드 조건으로 발효 온도는 $6^{\circ}C$, 발효기간은 겨울철 111시간, 봄 가을철 58시간으로 설정하고, 발효 후 즉시 $-2--1^{\circ}C$에서 보관하는 것으로 설정하였다. 김치 발효 보관 모드 적용에 따른 김치특성을 조사하였을 때, 모드 적용 김치시료는 일반보관 모드( $-2--1^{\circ}C$)에서 보관된 대조구 김치시료보다 발효초기(2주)에는 산도 증가가 높게 나타났으나 장기저장 시(12주)에는 모두 비슷한 산도를 나타내었다. 총유산균수는 대조구 김치시료보다 최대 약 $10^1CFU/mL$ 더 높일 수 있고, 이때 검출되는 총유산균 중 Leuconostoc속의 수는 대조구 보다 더 높은(약 $10^1-10^2CFU/mL$) 상태로 김치저장기간 내(12주) 유지됨을 알 수 있었다. 이에 따라 모드 적용 김치시료는 단맛 및 씹었을 때 탄산미 등에 의한 청량감이 우수하여 종합적 기호도가 대조구보다 높게 평가되었다. 본 연구결과는 기존의 저온유지( $-2--1^{\circ}C$)로 발효 억제에 의한 단순 김치보관기능에서 더 나아가 최적의 김치 발효 보관 모드 기능부여로 맛있는 발효 김치 구현과 이의 오랜보관(12주)이 가능함을 시사한다.

• 한국토양비료학회지
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• 제46권1호
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• pp.65-72
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• 2013

This study was carried out to understand the long-term effects of organic waste treatments on the fate of heavy metals in soils originated from the organic wastes and consequent uptake of heavy metals by plant, together with examination of changes in soil properties and plant growth performance. In this study, the soils treated with three different organic wastes (municipal sewage sludge, alcohol fermentation processing sludge, pig manure compost) at three different rates (12.5, 25.0, 50.0 ton $ha^{-1}yr^{-1}$) for 7 years (1994 - 2000) were used. To see the long-term effect, plant growth study and soil examination were conducted twice in 2000 and 2010, respectively. There was no additional treatments of organic wastes for 10 years after the organic waste treatment for 7 years. Compared to plant growth examination conducted in 2000 using radish (Raphanus sativus cv. sodamaltari), it appeared that height, root length and diameter, fresh weight of radish grown in 2010 decreased in the plots treated with municipal sewage sludge and alcohol fermentation processing sludge and that the extent of decrease was higher with increase of sludge application rates. On the other hand, pig compost treatment increased plant height, root length and diameter, fresh weight with increasing application rates. Cu and Pb concentrations in radish root and leaves increased in 2010 compared to those in 2000 while Ni concentrations in root and leaves decreased. Zn concentration was increased only in the soils treated with pig manure compost. Multiple regression analysis among heavy metal species fractions in soils, soil pH, and metal concentrations in radish root and leaves indicated that the metal uptake by radish was governed mainly by the soil pH and subsequent increase of available heavy metal fractions in soils with organic waste treatments.

• Journal of Microbiology and Biotechnology
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• 제24권12호
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• pp.1664-1672
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• 2014

In this study, a fibrous bed bioreactor (FBB) was used for $\small{D}$-lactic acid ($\small{D}$-LA) production by Sporolactobacillus inulinus Y2-8. Corn flour hydrolyzed with ${\alpha}$-amylase and saccharifying enzyme was used as a cost-efficient and nutrient-rich substrate for $\small{D}$-LA production. A maximal starch conversion rate of 93.78% was obtained. The optimum pH for $\small{D}$-LA production was determined to be 6.5. Ammonia water was determined to be an ideal neutralizing agent, which improved the $\small{D}$-LA production and purification processes. Batch fermentation and fed-batch fermentation, with both free cells and immobilized cells, were compared to highlight the advantages of FBB fermentation. In batch mode, the $\small{D}$-LA production rate of FBB fermentation was 1.62 g/l/h, which was 37.29% higher than that of free-cell fermentation, and the $\small{D}$-LA optical purities of the two fermentation methods were above 99.00%. In fe$\small{D}$-batch mode, the maximum $\small{D}$-LA concentration attained by FBB fermentation was 218.8 g/l, which was 37.67% higher than that of free-cell fermentation. Repeate$\small{D}$-batch fermentation was performed to determine the long-term performance of the FBB system, and the data indicated that the average $\small{D}$-LA production rate was 1.62 g/l/h and the average yield was 0.98 g/g. Thus, hydrolyzed corn flour fermented by S. inulinus Y2-8 in a FBB may be used for improving $\small{D}$-LA fermentation by using ammonia water as the neutralizing agent.

• Asian-Australasian Journal of Animal Sciences
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• 제19권11호
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• pp.1617-1622
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• 2006

Long-term storage of feeds or feedstuffs in high temperature and humid conditions can be difficult because of microbial contamination. Essential oil isolated from industrial waste citrus peel could be used as a preservative because it is likely to have anti-bacterial and anti-fungal activity. Our objective was to determine whether different levels (0.028, 0.056 and 0.112 g/kg) of citrus essential oil (CEO) would provide anti-microbial activity and enhance preservation of animal feed without influencing rumen fermentation. At 0.112 g/kg, CEO inhibited growth of Escherichia coli (ATCC 25922) and Salmonela enteritidis (IFO 3313). Growth of E. coli recovered after 24 h of incubation, but S. enteritidis continued to be inhibited for 72 h. Preservation of antibiotic-free diets for swine was assessed by observing anti-aflatoxin activity. Aflatoxin was detected in control feed samples on days 16 (8 ppb) and 21 (8 ppb) and in anti-fungal agent (AA) treated samples on days 16 (2 ppb) and 21 (4 ppb). However, aflatoxin was not detected in feed samples treated with CEO. Treatment with CEO and AA did not influence ruminal pH, dry matter digestibility (DMD) or organic matter digestibility (OMD) over 48 h of incubation in rumen fluid. Acetate and propionate were slightly higher with CEO treatment (p<0.05), but total concentration of volatile fatty acid (VFA) was not significantly affected by treatment. Ammonia-N concentration was slightly higher for the control treatment (p<0.05). This study showed that treating feed with CEO enhances preservation of animal feed without influencing in vitro rumen fermentation.

• 한국초지조사료학회지
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• 제44권2호
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• pp.113-117
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• 2024

본 연구는 옥수수 사일리지에서 첨가제 처리와 저장기간을 달리 하였을 때 사일리지의 품질 변화 및 미생물 군집 변화를 검토함으로써 품질 향상 방안을 찾기 위해 수행되었다. 각 미생물 미접종 시험구(CON)와 미생물 접종 시험구(ADD) 내에서 저장기간에 따른 옥수수 사일리지의 영양소 함량의 변화는 없었다(p>0.05). 그러나 각 시험구 내에서 저장기간에 따른 건물(DM)의 감소(CON, 35.9~33.2%; ADD, 34.5~32.7%; p<0.05)와 젖산 함량의 증가(CON, 6.03~6.71%; ADD, 6.02~9.00%; p<0.05) 및 Lactobacillales의 상대적 비율의 증가(CON, 34.3~79.5%; ADD, 84.8~93.3%)는 발효 120일까지 지속적인 발효가 진행되었음을 나타낸다. 옥수수 사일리지의 발효 전에는 Enterobacterales (33.0%), Flavobacteriales (14.4%), Sphingobacteriales (12.7%), Burkholderiales (9.28%), Pseudomonadales (6.18%)등이 우점하였으나, 발효 후 Lactobacillales (69.4%), Bacillales (11.5%), Eubacteriales (7.59%)의 우점으로 인해 미생물의 다양성이 급격히 감소하였다. 결과적으로 옥수수 사일리지는 모든 저장기간에서 첨가제 유무에 관계 없이 양호한 발효 품질을 유지하였으나, 장기간 저장에도 발효가 지속되는 점과 호기적 안정성을 고려한다면 미생물 첨가제를 이용하는 것이 유리할 것으로 사료된다.

• 임산에너지
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• 24권2호
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• pp.1-9
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• 2005

친환경적으로 돈분뇨를 처리하기 위하여 목질칩을 이용한 정화조에서 장기 처리한 목질칩과 돈분뇨 성분의 변화 양상을 관찰하였다. 자체 제작한 정화조에 히터를 가동하면서 3일 후 발효 적정온도인 $55{\sim}60^{\circ}C$에 도달하였고, $180{\iota}$/일 돈분뇨 분해능을 보기는 정화조에서 사용하는 목질칩의 성분은 돈분뇨의 처리시기가 경과함에 따라 회분의 양이 증가하여 돈분뇨 자체에 포함되어 있는 여러 무기물 함량이 더해진 것으로 보였다. 알칼리와 유기용매추출물 및 Klason 리그닌함량은 거의 변화가 없었고, 무처리칩에 비해 흘로셀룰로오스의 양은 약 10% 감소하여 발효 중 목질칩이 부탄소원으로 이용되었을 가능성이 있다고 판단되었다. 장기 처리된 돈분뇨의 성분 중 무기물 함량($Ca^{2+},\;Mg^{2+},\;K^+,\;Na^+$ 등)은 무처리칩에 비해 처리기간에 파라 증가하는 경향을 보였고, 중금속(Cd, As, Cu 등)은 거의 검출되지 않았다. 돈분뇨 원액에 비해 전질소 함량은 감소하나 무처리칩보다는 높은 수치를 보여 나중에 돈분뇨를 발효, 분해한 목질칩을 산지의 퇴비화에 사용해도 환경적 문제가 없을 것이라고 판단되었다. 장기 처리에 따른 미생물 변이는 반응기 내의 온도가 급격히 상승하면서 생균수가 증가하였다.

• Asian-Australasian Journal of Animal Sciences
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• 제32권10호
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• pp.1528-1539
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• 2019

Objective: To evaluate the effects on microbial diversity and biochemical parameters of gradually increasing temperatures, from $5^{\circ}C$ to $25^{\circ}C$ on corn silage which was previously fermented at ambient or low temperature. Methods: Whole-plant corn silage was fermented in vacuum bag mini-silos at either $10^{\circ}C$ or $20^{\circ}C$ for two months and stored at $5^{\circ}C$ for two months. The mini-silos were then subjected to additional incubation from $5^{\circ}C$ to $25^{\circ}C$ in $5^{\circ}C$ increments. Bacterial and fungal diversity was assessed by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) profiling and biochemical analysis from mini-silos collected at each temperature. Results: A temperature of $10^{\circ}C$ during fermentation restricted silage fermentation compared to fermentation temperature of $20^{\circ}C$. As storage temperature increased from $5^{\circ}C$ to $25^{\circ}C$, little changes occurred in silages fermented at $20^{\circ}C$, in terms of most biochemical parameters as well as bacterial and fungal populations. However, a high number of enterobacteria and yeasts (4 to $5\;log_{10}$ colony forming unit/g fresh materials) were detected at $15^{\circ}C$ and above. PCR-DGGE profile showed that Candida humilis predominated the fungi flora. For silage fermented at $10^{\circ}C$, no significant changes were observed in most silage characteristics when temperature was increased from $5^{\circ}C$ to $20^{\circ}C$. However, above $20^{\circ}C$, silage fermentation resumed as observed from the significantly increased number of lactic acid bacteria colonies, acetic acid content, and the rapid decline in pH and water-soluble carbohydrates concentration. DGGE results showed that Lactobacillus buchneri started to dominate the bacterial flora as temperature increased from $20^{\circ}C$ to $25^{\circ}C$. Conclusion: Temperature during fermentation as well as temperature during storage modulates microorganism population development and fermentation patterns. Silage fermented at $20^{\circ}C$ indicated that these silages should have lower aerobic stability at opening because of better survival of yeasts and enterobacteria.