• 청정기술
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• 제27권2호
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• pp.115-123
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• 2021

본 연구는 무기 실리카 껍질(shell)과 유기 고분자 코어(core)로 구성된 매우 균일한 유-무기 복합체 입자 제조의 방법에 관한 것이다. 먼저, 미세유체 기술을 이용하여 균일한 크기를 지니는 유기 고분자 코어 입자를 제조하였다. 코어 입자의 제조 과정에서 코어 입자의 제조 과정에서 광 경화성 유기 물질이 포함된 분산상과 연속상의 유속을 독립적으로 제어함으로써 균일한 액적을 형성하였다. 액적이 형성됨과 동시에, 미세유체 채널의 말단에서 자외선 조사에 의해 액적이 광중합 되어 코어 입자로 형성된다. 더불어, 폴리알릴아민 하이드로클로라이드(polyallylamine hydrochloride, PAH)와 인산 이온(phosphate ion)으로 구성된 나노 복합체는 최적화된 pH 조건에서 수소결합과 정전기적 인력 같은 강력한 상호작용을 통해 코어 입자에 코팅된다. 폴리아민 나노 복합체에 존재하는 PAH 주쇄의 아민 그룹들은 규산(silicic acid)의 축합(condensation) 반응을 촉매하여, 코어 입자 표면의 실리카 나노입자 성장을 시킬 수 있었다. 따라서, 본 방법을 통해 유기 코어에 무기 실리카 나노입자로 코팅된 유-무기 복합체 입자를 제조할 수 있었다. 최종적으로, 본 연구에서 제시한 방법은 보다 온화하며 환경친화적인 조건 하에서 단시간 내에 유-무기 복합체 입자를 합성할 수 있으며, 다양한 모양과 크기를 갖는 코어 입자에 적용되어 넓게 활용될 수 있다.

• Journal of Microbiology and Biotechnology
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• 제22권3호
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• pp.400-406
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• 2012

To improve the hydrogen yield from biological fermentation of organic wastewater, a co-culture system of dark- and photo-fermentation bacteria was investigated. In a pure-culture system of the dark-fermentation bacterium Clostridium butyricum, a pH of 6.25 was found to be optimal, resulting in a hydrogen production rate of 18.7 ml-$H_2/l/h$. On the other hand, the photosynthetic bacterium Rhodobacter sphaeroides could produce the most hydrogen at 1.81mol-$H_2/mol$-glucose at pH 7.0. The maximum specific growth rate of R. sphaeroides was determined to be 2.93 $h^{-1}$ when acetic acid was used as the carbon source, a result that was significantly higher than that obtained using either glucose or a mixture of volatile fatty acids (VFAs). Acetic acid best supported R. sphaeroides cell growth but not hydrogen production. In the co-culture system with glucose, hydrogen could be steadily produced without any lag phase. There were distinguishable inflection points in a plot of accumulated hydrogen over time, resulting from the dynamic production or consumption of VFAs by the interaction between the dark- and photo-fermentation bacteria. Lastly, the hydrogen production rate of a repeated fed-batch run was 15.9 ml-$H_2/l/h$, which was achievable in a sustainable manner.

• Journal of Microbiology and Biotechnology
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• 제22권5호
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• pp.668-673
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• 2012

Biohydrogen production from organic wastewater by anaerobically activated sludge fermentation has already been extensively investigated, and it is known that hydrogen can be produced by glucose fermentation through three metabolic pathways, including the oxidative decarboxylation of pyruvic acid to acetyl-CoA, oxidation of NADH to $NAD^+$, and acetogenesis by hydrogen-producing acetogens. However, the exact or dominant pathways of hydrogen production in the anaerobically activated sludge fermentation process have not yet been identified. Thus, a continuous stirred-tank reactor (CSTR) was introduced and a specifically acclimated acidogenic fermentative microflora obtained under certain operation conditions. The hydrogen production activity and potential hydrogen-producing pathways in the acidogenic fermentative microflora were then investigated using batch cultures in Erlenmeyer flasks with a working volume of 500 ml. Based on an initial glucose concentration of 10 g/l, pH 6.0, and a biomass of 1.01 g/l of a mixed liquid volatile suspended solid (MLVSS), 247.7 ml of hydrogen was obtained after a 68 h cultivation period at $35{\pm}1^{\circ}C$. Further tests indicated that 69% of the hydrogen was produced from the oxidative decarboxylation of pyruvic acid, whereas the remaining 31% was from the oxidation of NADH to $NAD^+$. There were no hydrogen-producing acetogens or they were unable to work effectively in the anaerobically activated sludge with a hydraulic retention time (HRT) of less than 8 h.

• Asian-Australasian Journal of Animal Sciences
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• 제14권7호
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• pp.947-950
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• 2001

To improve the low content of crude protein and low quality fermentation of napiergrass silage, ensiling with phasey bean was examined. Napiergrasses, (Pennisetum purpureum cv. Merkeron), hybrid napiergrass (Pennisetum purpureum${\times}$ Pennisetum typhoides) and phasey bean (Macroptilium lathyroides cv. Murray) were cultivated in Fukuoka, Japan. The first growth of napiergrasses and phasey bean were harvested at 90 days of age and chopped into about 1 cm lengths. The mixing levels of phasey bean with napiergrasses were 0, 25, 50 and 75; 700 g of plant materials were ensiled into a laboratory silo (1.0 litre. polyethylene container) and incubated for 30 days. After opening silos, pH, total nitrogen (TN), volatile basic nitrogen (VBN) and organic acids (lactic acid: LA, acetic acid: AA, butyric acid: BA) were determined. The experiment was a factorial design of $2{\times}4$ with 3 replicates. The data were analyzed statistically by two-way analysis of variance. Without inclusion of phasey bean, lower quality was observed for hybrid silage than for Merkeron silage. The inclusion of phasey bean at the rate of 25% increased DM and TN, and decreased pH value, VBN/TN, AA and BA in both Merkeron and hybrid napiergrass silages. The value of pH, TN, VBN/TN, AA and BA were not significantly different among 25, 50 and 75% mixing levels of phasey bean. LA production increased significantly with the increase in phasey bean mixing level in both hybrid and Merkeron silages. At all mixing levels of phasey bean, LA production did not show significant differences between Merkeron and hybrid silages.

• 한국식품저장유통학회지
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• 제3권2호
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• pp.155-170
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• 1996

In order to determine the physiolosical characteristics of plum fruits(Oishi wase) during maturation and guilty according to temperature after harvest, (2-chloroethyl) phosphonic acid(ethphon) 390ppm was sprayed on plum tree 11days before commercial matuarity in Suwon area. And also this study was acted to investigate fruits quility(Formosa) influenced by temperature(room, low) and polyethylene films(0.03, 0.06, 0.1mm), 1. Effect of ethphon on the fruits maturation and fruits(Oishi wase) quility according to temperature ofter harvest. Ethephon stimulated fruits ripening but the firmness was reduced rapidly. Soluble solids and titratable acidity was not very different than each treatment. Carbon dioxide and ethylene production were advanced and the production peak were shown earlier by ethephon treatment as compared with control fruit. Anthocyanin development was enhansed rapidly by ethephon treatment but it exerted a bad influence on fruits color after harvest, The soluble sugars in fluits were mainly glucose, sucrose, and fructose. Those content were higher in treated fruit than control. The organic acid was mainly malic acid. The shelf life was less than about 5days at room temperature and about 10 days at low temperature. 2. Fruits(Formosa) quility as affected by polyethylene film bagging. The polyethylene films well maintained the firmness both room and low temperature. Low temperature was more effective in maintaining titratable acidity than room temperature, especially polyethylene films. On the Other hand, soluble solids content was not shown wide differance between room and low temperature. Polyethylene film showed a high resperation rate, the rate was higher at room temperature than low temperature and thicker films revealed higher rate. Otherwise, ethylene production was low in all treatment Polyethylene film inhibited the coloration of fruits, decreased anthocyanin content. Fruits coloration delayed by low temperature in control. The shelf life of plum fruits was about 6 days at room temperature and 13 days at low temperature in control Polyethylene film had no advantage on shelf life both at room and low temperature.

• 생명과학회지
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• 제32권2호
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• pp.119-124
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• 2022

막걸리 식초 생산에 효과적인 초산균을 분리하기 위해 다양한 시료에서 초산균을 검색하였고, 그 중 초산 생산이 우수한 균주인 Acetobacter pasteurianus CK-1을 최종 분리하였다. 분리균주의 최적 생육온도는 30.0℃로 확인되었고, pH 6.0에서 가장 왕성하게 생장하였으며, pH 5.5~6.5 범위에서 잘 생장하였다. A. pasteurianus CK-1은 배지의 초기 에탄올 농도가 4%일 때 가장 왕성하게 생장하였고, 7%의 에탄올 농도에서도 생장이 가능하였다. 분리균주를 막걸리에 접종하여 초산 발효를 유도하였을 때, 발효 초기 pH 3.54였던 것이 발효가 진행되면서 점차 낮아져서 발효 18일 후에는 pH 2.77이 되었다. 산도는 발효 초기에 0.75%였던 것이 발효 4일경부터 점차 증가하여 최종 산도는 5.54%로 증가하였다. A. pasteurianus CK-1 발효 식초에서는 acetic acid가 3,575.7±48.6 mg%로 높게 검출되었고, malic acid와 citric acid는 각각 2,150.8±27.6 mg%와 55.8±3.7 mg%로 검출되었다. 접종한 균주의 종류에 따라 생성되는 유기산의 함량과 비율이 유의하게 차이가 나는 것을 확인하였다. 초산 발효 동안 발효액 내의 효모와 A. pasteurianus CK-1의 개체군은 반비례적으로 변화하였다. 발효 초기에는 효모가 우점하였으나, 발효가 진행됨에 따라 A. pasteurianus CK-1이 서서히 증식하여 10일 후에는 정체기에 이르렀다.

• 한국미생물·생명공학회지
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• 제23권4호
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• pp.461-471
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• 1995

The heterofermentative Leuconostoc mesenteroides, which is propagated from the initial to the intermediate stage of Kimchi fermentation, produces organic acids and carbon dioxide to impart refreshment, weak acid taste to Kimchi. But owing to lactic acid production by the homofermentative Lactobacillus Plantarum, Kimchi finally reaches its acidified state. So, Leu. mesenteroides was isolated from Kimchi and identified and was improved by mutation for carbon dioxide production at low pH, and for the high total acceptability. We tested with a wild-type strain K-1 and its improved mutant strain M-10 of Leu. mesenteroides. The wild-type strain K-1 could grow in pH 4.2 at 30$\circ$C or 20$\circ$C, and in pH 5.0 at 10$\circ$C. But the mutant strain M-10 could grow in pH 3.3 at 10$\circ$C. In the respect of total acceptability, mutant strain M-10 inoculated Kimchi was ever better than any others. Mutant M-10 inoculated Kimchi prolonged the optimum ripening period of Kimchi up to two times as compared with the control group.

• International Journal of Oral Biology
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• 제43권1호
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• pp.37-42
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• 2018

It is noted that Streptococcus mutans (S. mutans) triggers dental caries establishment by two major factors: the synthesis of organic acids, which demineralize dental enamel, and the synthesis of glucans, which mediate the attachment of bacteria to the tooth surface. Therefore, it is noted that the development of a more effective, substantial and safe preventive agent that works against dental caries and periodontal disease is required at this time. For this reason, the present study was designed to investigate the effect of croton seed ethanol extracts on the growth, acid production, adhesion, and insoluble glucan synthesis of S. mutans. In this case, the ethanol extract of croton seed showed concentration dependent inhibitory activity against the growth, acid production and adhesion of S. mutans. Especially, it is important to note that it has produced significant inhibition at the concentration of 0.1 and 0.2 mg/ml as compared to the control group. Moreover, these results suggest that the application of croton seed extract may be considered to be a useful method for the prevention of dental caries.

• Food Science and Biotechnology
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• 제17권6호
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• pp.1279-1284
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• 2008

When cheonggukjgang was manufactured using a Bacillus subtilis CH10-1 starter culture, a short-term fermentation for 14-18 hr appeared to be the optimal for the raw cheonggukjang to avoid the formation of a bitter taste and to contain a high concentration of free sugars, whereas a long-term fermentation for more than 4 days was the optimal for the cheonggukjang for stew in order to contain a high concentration of free amino and organic acids, which are responsible for sweet, savory, and bitter tastes present in stewed cheonggukjang, During activation of murine splenic T cells with phytohemagglutinin (PHA), the presence of either poly-$\gamma$-glutamic acid ($\gamma$-PGA) or partially hydrolyzed $\gamma$-PGA resulted in reduction in the level of interferon-$\gamma$ production and enhancement in the level of interleukin-5 production, possibly due to suppression of Th1 activity and augmentation of Th2 activity. Taken together these results indicate that the raw cheonggukjang and the cheonggukjang for stew are different in their quality and taste as well as immunomodulating activity.

• Environmental Engineering Research
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• 제24권2호
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• pp.202-210
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• 2019

In order to maximize the utilization of sewage sludge, a waste from wastewater treatment facility, the residual sewage sludge generated after lipid and carbohydrate extraction for biodiesel and bioethanol production was used to produce bio-oil by pyrolysis. Thermogravimetric analysis showed that sludge pyrolysis mainly occurred between 200 and $550^{\circ}C$ (with peaks formed around 337.0 and $379.3^{\circ}C$) with the decomposition of the main components (carbohydrate, lipid, and protein). Bio-oil was produced using a micro-tubing reactor, and its yield (wt%, g-bio-oil/g-residual sewage sludge) increased with an increase in the reaction temperature and time. The maximum bio-oil yield of 33.3% was obtained after pyrolysis at $390^{\circ}C$ for 5 min, where the largest amount of energy was introduced into the reactor to break the bonds of organic compounds in the sludge. The main components of bio-oil were found to be trans-2-pentenoic acid and 2-methyl-2-pentenoic acid with the highest selectivity of 28.4% and 12.3%, respectively. The kinetic rate constants indicated that the predominant reaction pathway was sewage sludge to bio-oil ($0.1054min^{-1}$), and subsequently to gas ($0.0541min^{-1}$), rather than the direct conversion of sewage sludge to gas ($0.0318min^{-1}$).