• Journal of Microbiology and Biotechnology
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• 제15권4호
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• pp.716-721
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• 2005

The role of an effective microbial species is critical to the successful application of biological processes to remove sulfur compounds. A bacterial strain was isolated from the soil of a malodorous site and identified as Burkholderia spp. This isolate was able to oxidize thiosulfate to sulfate, with simultaneous pH decrease and accumulation of elemental sulfur. The specific growth rate and the sulfate oxidation rate using the thiosulfate basal medium were $0.003 h^{-1}\;and\;3.7 h^{-1}$, respectively. The isolated strain was mixotrophic, and supplementation of $0.2\%$ (w/v) of yeast extract to the thiosulfate-basal medium increased the specific growth rate by 50-fold. However, the rate of sulfate oxidation was more than ten times higher without yeast extract. The isolate grew best at pH 7.0 and $30^{\circ}C$, and the sulfate oxidation rate was the highest at 0.12 M sodium thiosulfate. In an upflow biofilter, the isolated strain was able to degrade $H_2S\;with\;88\%$ efficiency at 8 ppm and 121/h of incoming gas concentration and flow rate, respectively. The cell density at the bottom of the column reached $3.2{\times}10^8$ CFU/(g bead) at a gas flow rate of 121/h.

• Food Science and Biotechnology
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• 제15권5호
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• pp.715-720
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• 2006

This study was performed to develop a predictive model for the growth kinetics of Listeria monocytogenes in tryptic soy broth (TSB) using a response surface model with a combination of potassium lactate (PL), temperature, and pH. The growth parameters, specific growth rate (SGR), and lag time (LT) were obtained by fitting the data into the Gompertz equation and showed high fitness with a correlation coefficient of $R^2{\geq}0.9192$. The polynomial model was identified as an appropriate secondary model for SGR and LT based on the coefficient of determination for the developed model ($R^2\;=\;0.97$ for SGR and $R^2\;=\;0.86$ for LT). The induced values that were calculated using the developed secondary model indicated that the growth kinetics of L. monocytogenes were dependent on storage temperature, pH, and PL. Finally, the predicted model was validated using statistical indicators, such as coefficient of determination, mean square error, bias factor, and accuracy factor. Validation of the model demonstrates that the overall prediction agreed well with the observed data. However, the model developed for SGR showed better predictive ability than the model developed for LT, which can be seen from its statistical validation indices, with the exception of the bias factor ($B_f$ was 0.6 for SGR and 0.97 for LT).

• Journal of Microbiology and Biotechnology
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• 제23권12호
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• pp.1747-1756
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• 2013

The aim of this paper was to study the effect of spent medium recycle on Spodoptera exigua Se301 cell line proliferation, metabolism, and baculovirus production when grown in batch suspension cultures in Ex-Cell 420 serum-free medium. The results showed that the recycle of 20% of spent medium from a culture in mid-exponential growth phase improved growth relative to a control culture grown in fresh medium. Although both glucose and glutamine were still present at the end of the growth phase, glutamate was always completely exhausted. The pattern of the specific glucose and lactate consumption and production rates, as well as the specific glutamine and glutamate consumption rates, suggests a metabolic shift at spent medium recycle values of over 60%, with a decrease in the efficiency of glucose utilization and an increase in glutamate consumption to fuel energy metabolism. Baculovirus infection provoked a change in the metabolic pattern of Se301 cells, although a beneficial effect of spent medium recycle was also observed. Both growth rate and maximum viable cell density decreased relative to uninfected cultures. The efficiency of glucose utilization was dramatically reduced in those cultures containing the lowest percentages of spent medium, whereas glutamine and glutamate consumption was modulated, thereby suggesting that infected cells were devoted to virus replication, retaining their ability to incorporate the nutrients required to support viral replication. Recycle of 20% of spent medium increased baculovirus production by around 90%, thus showing the link between cell growth and baculovirus production.

• 무역학회지
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• 제44권3호
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• pp.15-24
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• 2019

The study conducted an empirical analysis of the impact of FDI on economic growth in four Asian countries: China, India, Vietnam and Korea. With panel data for the 1990-2017 period, the research model was developed for foreign direct investment (FDI), export amount (EX), government expenditure (G), exchange rate (EXR), and labourable population (L). The panel analysis results show that the increase in FDI, exports, government expenditure, labourable population significantly increased economic growth. The comparison analysis for each country revealed that FDI, exports and government expenditure significantly affect economic growth in China, that exports and government expenditure significantly affect economic growth in Korea, that FDI significantly affected economic growth in Vietnam, and that the increase in the workforce contributed to economic development in India. This paper characterized the different factors of economic growth in the four Asian countries. These results suggest that setting economic priorities to suit the specific economic conditions of each country is a shortcut to more efficient economic growth.

• 한국미생물·생명공학회지
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• 제24권4호
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• pp.519-524
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• 1996

The kinetics of growing microalga, Spirulina platensis was investigated to treat swine wastes with optimum growth conditions. Temperature was varied from 15 to 40$\circ$C at three different light intensities, 6 W/m$^{2}$, 12 W/m$^{2}$ and 24 W/m$^{2}$. The specific growth rate was increased as temperature increased up to 30$\circ$C. The activation energy was estimated as 13.5 kcal/mol by an Arrhenius relationship. 0.24 (1/day) of specific growth rate was obtained from batch cultivation with 30% swine wastes, compared to 0.31 (1/day) from clean culture. It was found that Spirulina platensis was able to reduce 70-93% of PO$_{4}$$^{3-}$ -P, 67-93% of inorganic nitrogen, 80-90% of COD and 37-56% organic nitrogen by adding various concentrations of swine wastes for 12 days of batch cultivation. Rate constants for removing nitrates and phosphates in treating swine wastes were estimated as 0.17 (1/day) and 0.14 (1/day) in the first order reaction, respectively. 1.52 (g/L) of maximum cell density was maintained at 0.20 (1/day) of dilution rate in continuous culture, adding 20% swine wastes for 30 days. The chemical composition of the biomass obtained from the process showed 58.7% of protein, 11.0% of lipid and 15.6% of ash.

• 한국양식학회지
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• 제15권3호
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• pp.131-138
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• 2002

수온과 사육밀도에 따른 홍민어의 성장을 조사하기 위하여 20${\pm}$0.5, 23${\pm}$0.5 그리고 26${\pm}$0.5$^{\circ}C$로 각각 조절한 항온 수조에서 평균전장 4.60${\pm}$0.3 cm, 체중 1.17${\pm}$0.6 g되는 치어를 32주간 비교 사육하였으며, 평균 전장 26.6${\pm}$1.7cm, 체중 213.6${\pm}$46.7 g되는 개체를 대상으로 사육밀도 2.16, 4.24 그리고 6.40 kg BW/㎥로 조절하여 25주 동안 사육하였다. 수온에 따른 성장실험에서 전장, 체중, 일간 성장률에서 26$^{\circ}C$, 23$^{\circ}C$, 20$^{\circ}C$ 순으로 수온이 높을수록 빠른 성장을 하였다. 일간섭식율에서도 26$^{\circ}C$에서 가장 높아 수온이 높을수록 높은 값을 나타내었다(P<0.05). 사육밀도에 따른 성장실험에서 전장, 체중, 일간성장률에서 저밀도 실험구에서 높은 값을 나타내었고 일간섭식율에서도 같은 경향이었으며(P<0.05), 실험 시작시 2.16 kg BW/$m^3$, 4.24 kg BW$m^3$ 그리고 6.40 kg BW$m^3$의 사육밀도는 실험 종료시 각각 7.26 kg BW$m^3$, 14.01 kg BW$m^3$, 19.17kg BW$m^3$로 증가하여 6.40 kg$m^3$에서 생산성이 가장 높았다

• Biotechnology and Bioprocess Engineering:BBE
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• 제5권2호
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• pp.110-117
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• 2000

Relationship between monoclonal antibody (MAb) productivity and growth rate, and effects of high cell density on MAb production rate increased with increasing specifis growth rate in both suspended and immobilized continuous cultures indicate a positively growth-associated relationship between MAb productivity and growth rate. moreover, the specific production rate was higher in the immobilized cell culture than that in suspended one at all dilution rates. In order to clarify these phenomana, MAb mPNA experession and cell cycle distribution were investigated in bacth cultures with immobilized cells and suspended cells. RT-PCR was used for observation of MAb mRNA expression and a two-color bromodeoxyuridine (BrdU)/propidium iodide (PI) flow cytometry method for determination of cell cycle distribution. The results revealed that MAb nRNA expression until dead phase, which was longer than in suspended cell. The cell cycle distribution patterns were observed almost the same for both immobilized and suspended cells. Such results may imply that a high cell density state has positive influence on the mRNA expression and on growth-associated Mab productivity of T0405 cells.

• 생명과학회지
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• 제26권6호
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• pp.646-650
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• 2016

본 연구는 염색체 가공기술(chromosome manipulation technique)을 이용하여 다양한 개수의 염색체를 가진 균주들의 세포 성장속도 및 life span을 비교하여 염색체 수의 증가가 세포 생리에 미치는 영향을 조사하였다. 16개의 염색체를 가지는 숙주세포 FY833 균주와 18개의 염색체를 가지는 YKY18 및 YKY18R 균주, 24개의 염색체를 가지는 YKY24 균주와 30개의 염색체를 가지는 YKY30 균주를 사용하여 specific growth rate를 비교해 본 결과, YKY18 균주와 YKY24 균주는 세포성장의 변화가 거의 없었으나, YKY18R 균주와 YKY30 균주에서는 숙주세포에 비해 각각 25%와 40% 이상 성장이 감소됨을 확인 할 수 있었다. 또한 염색체 수와 노화의 관계를 알아보기 위해 replicative life span을 조사해 본 결과, YKY24균주와 YKY30 균주에서 숙주세포에 비해 약 14%와 45% 정도로 life span이 감소했음을 알 수 있었다. 노화인자로 알려져 있는 telomere의 길이도 인공염색체의 수가 증가될수록 점점 다양해지고 길이가 짧아짐을 확인 할 수 있었다. 따라서 염색체 수의 증가도 새로운 노화원인이 될 수 있다는 가능성을 제시하였고, 본 연구 결과가 다양한 인공염색체를 가진 산업용 균주의 안정적인 개량을 위한 기초 자료로 활용될 수 있을 것이라 기대한다.

• 한국미생물·생명공학회지
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• 제17권5호
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• pp.421-428
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• 1989

물성조정제로서 고전도의 다당류를 생산하는 토양세균을 분리 선발하여 동정한 결과 Pseudomonas delafieldii로 판단되었다. 이 세균의 증식을 위한 pH와 온도는 6.5 및 3$0^{\circ}C$이었다. 최대 비성장속도는 0.25 h$^{-1}$이며 염류배지에서 다당류의 비생산속도, 증식수율 및 다당류 생산수율은 6.25mg/g-cell/h, 54.5%, 38.39%이었다. 본 다당류는 포도당과 gluconolactone을 몰비로 1.9：1.0로 함유한 $\beta$-glucan 으로 추정되었으며 원인 분석결과 탄소 31.85% 수소 31.85% 수소 5.l5%를 함유하고 아세틸기를 1.35%가지고 있었으며 고유점도는 42.84dl/g, 분자량은 5.64$\times$$10^7$이었다.

• KSBB Journal
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• 제8권1호
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• pp.17-22
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• 1993

$1.96{\times}10^{-5}$(IU/cell/hr) of specific scu-PA production rate was obtained from HEK cells in maintaining ca. $8{\times}10^{5}$(cells/ml) of maximum roll density at 10(ml/hr) of perfusion rate with recycling 20% serum free conditioned media. It can be compared to $4{\times}10^{6}$(cells/ml) of maximum cell density and $4.56{\times}10^{-4}$(IU/cell/hr) of specific production rate in cultivating cells with 1% serum containing medium. Thc conversion ratio of scu-PA to tc-UK increased up to 55% as the recycling ratio increased; however, recycling the used medium seemed to have least negative effect on cell growth. It also showed that the recycling process had definitive advantage of using serum free medium in perfusion cultivation of HEK cell line.