• 생명과학회지
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• 제15권1호
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• pp.15-20
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• 2005

동충하초 Paecilomyces tenuipes C240의 균사체 배양과정에서 균사체 성장, 세포외 다당체 생산, 기질감소 속도를 표현할 수 있는 동력학적 모델을 제시하였다. 균사체 성장은 Logistic식을, 세포외 다당체 생산은 Luedeking-Piret 식을, 기질소모는 Luedeking-Piret 유사식을 각각 적용함으로써, 전체 균사체 배양과정을 예측할 수 있었다. 모델식에서 사용된 주요 kineti, constant들은 다음과 같다: 균사체의 최대 비성장속도${\mu}m,\;0.7281\;h^{-1};$; 다당체 생산에서의 growth-associated constant $(\alpha),\;0.1743g(g\;cells)^{-1}$; non-growth-associated constant $(\beta),\;0.0019g(g\;cells)^{-1}\;;$ maintenance coefficient ($(m_s),\;0.0572g\;(g\;cells)^{-1}$·5L 발효조에서 얻은 균사체 성장, 세포외 다당체 생산, 기질감소 속도자료들을 모델에서 예측한 결과와 비교한 결과 서로 잘 일치하는 것으로 보아, 본 연구에서 제안된 모델식은 이 동충하초 균사체 배양공정의 scale-up등의 프로세스 설계에 응용가능 할 것이며, 다른 종류의 동충하초 균사체 배양공정에도 적용가능 할 것으로 판단된다.

• Biotechnology and Bioprocess Engineering:BBE
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• 제11권1호
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• pp.43-47
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• 2006

Ginseng (Panax ginseng CA. Meyer) hairy root cultures, which are established via the infection of ginseng root discs with Rhizobium rhizogenes, have been used to construct profiles of both biomass growth and nutrient consumption in flask cultures. In a 250 mL shake flask culture, the maximum biomass was observed on the 59th day of the culture period, at 216.8 g (fresh wt) per liter or 11.4 g (dry wt) per liter. The hairy roots were determined to have a growth rate of 0.355 g-DW/g cells/day during the exponential growth phase and a maximum specific growth rate on day 7. Total ginseng saponin and phenolic compound contents were noted to have increased within the latter portion of the culture period. Linear correlations between increases in biomass weight and nutrient uptake were used to imply the conductivity yield $2.60g-DW/(L{\cdot}mS)$ and carbon yield 0.45 g-DW/(g sugar) in the 250 mL flask cultures. The biomass yield when two different nitrogen sources were used (ammonia and nitrate) was shown to remain approximately constant. at $0.47g-DW/(L{\cdot}mM\;NH_4$) and $0.33g-DW/(L{\cdot}mM\;NO_3$); it remained at these levels for 16 days with the ammonia. and for 24 days with the nitrate. The biomass yield when a phosphate source was used was also shown to remain approximately constant for 9 days, at $3.17g-DW/(L{\cdot}mM\;PO_4$), with an $R^2$ of 0.99.

• Preventive Nutrition and Food Science
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• 제13권2호
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• pp.104-111
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• 2008

As a way to account for the variability of the primary model parameters in the secondary modeling of microbial growth, three different regression approaches were compared in determining the confidence interval of the temperature-dependent primary model parameters and the estimated microbial growth during storage: bootstrapped regression with all the individual primary model parameter values; bootstrapped regression with average values at each temperature; and simple regression with regression lines of 2.5% and 97.5% percentile values. Temperature dependences of converted parameters (log $q_o$, ${\mu}_{max}^{1/2}$, log $N_{max}$) of hypothetical initial physiological state, maximum specific growth rate, and maximum cell density in Baranyi's model were subjected to the regression by quadratic, linear, and linear function, respectively. With an advantage of extracting the primary model parameters instantaneously at any temperature by using mathematical functions, regression lines of 2.5% and 97.5% percentile values were capable of accounting for variation in experimental data of microbial growth under constant and fluctuating temperature conditions.

• 한국수산과학회지
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• 제43권4호
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• pp.362-372
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• 2010

In order to understand what leads to the appearance of harmful Chattonella algae in the Yeosu coastal waters of Korea, we measured environmental parameters every week at one station from May to November, 2006, and April to October, 2007. Four species of Chattonella appeared during the monitoring period: C. antiqua, C. globosa, C. marina and C. ovata. The range of water temperature and salinity were $15.0-27.9^{\circ}C$ and 17.6~33.0 psu, respectively, when Chattonella appeared, and their maximum cell density (4,840 cells/L) was at $27.1^{\circ}C$ and 33.0 psu. During the monitoring periods, the range of dissolved inorganic nitrogen (DIN), phosphate (DIP) and chlorophyll $\alpha$ (Chl-$\alpha$) concentrations in surface waters were $1.20-52.23\;{\mu}M$ ($8.59{\pm}8.97\;{\mu}M$), $0.03-1.56\;{\mu}M$ ($0.47{\pm}0.31\;{\mu}M$) and $0.45-31.12\;{\mu}g/L$ ($3.58{\pm}4.77\;{\mu}g/L$), respectively. Chattonella occurred at low cell density when the Chl-$\alpha$ concentration increased because of supplied nutrients, whereas their cell density increased during the periods of rapid decrease in Chl-$\alpha$. The results of growth experiments based on batch culture showed that the half saturation constant ($K_s$) of C. antiqua on ammonium (${NH_4}^-$), nitrate (${NO_3}^-$) and phosphate (${PO_4}^{2-}$) were $3.89{\mu}M$, $5.01\;{\mu}M$ and $0.63\;{\mu}M$, respectively. These Ks values are higher than those reported for diatoms and other flagellates at the DIP concentration (average $0.47{\mu}M$) of Yeosu coastal waters. Although the maximum specific growth rate (${\mu}_{max}$) of C. antiqua was lower than diatoms, it was higher than those of other flagellates. Therefore, our results indicate that the DIP level in the study area was too low to support Chattonella blooms, although Chattonella species have physiological characteristics that enable them to grow more rapidly than other flagellates when nutrient levels are higher than their $K_s$.

• Journal of Microbiology
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• 제44권4호
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• pp.439-446
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• 2006

In this study, the growth kinetics of Lactobacillus rhamnosus and lactic acid production in continuous culture were assessed at a range of dilution rates $(0.05 h^{-1}\;to\;0.40h^{-1})$ using a 2L stirred tank fermenter with a working volume of 600ml. Unstructured models, predicated on the Monod and Luedeking-Piret equations, were employed to simulate the growth of the bacterium, glucose consumption, and lactic acid production at different dilution rates in continuous cultures. The maximum specific growth rate of L. rhamnosus, ${\mu}_{max}$, was estimated at $0.40h^{-1}$I, and the Monod cell growth saturation constant, Ks, at approximately 0.25g/L. Maximum cell viability $(1.3{\times}10^{10}CFU/ml)$ was achieved in the dilution rate range of $D=0.28h^{-1}\;to\;0.35h^{-1}$. Both maximum viable cell yield and productivity were achieved at $D=0.35h^{-1}$. The continuous cultivation of L. rhamnosus at $D=0.35h^{-1}$ resulted in substantial improvements in cell productivity, of 267% (viable cell count) that achieved via batch cultivation.

• 대한환경공학회지
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• 제28권2호
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• pp.144-149
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• 2006

Hexane을 유일 탄소 에너지원으로 하여 농화배양한 배양액으로부터 hexane 분해능이 우수한 EH741 균주를 순수 분리 동정하였고, 분리균주에 의한 hexane 생분해 특성을 조사하였다. EH741 균주는 Rhodococcus sp.로 동정되었고, 액상 배양계에서 hexane 용해도를 향상시키기 위해 첨가한 계면활성제 Pluronic F68(PF68)은 hexane 생분해 속도에 영향을 미치지 않았다. Hexane을 유일 탄소원으로 첨가한 무기염 배지에서 EH741의 최대 비성장속도(${\mu}_{max}$)값은 $0.04h^{-1}$이었고, 최대 hexane 분해속도($V_{max}$)와 포화상수($K_s$)는 각각 $161{\mu}mol{\cdot}g-DCW^{-1}{\cdot}h^{-1}$ 및 10.5 mM이었다. Rhodococcus sp. EH741은 hexane 처리를 위한 생물학적 공정에 유용하게 활용될 것으로 사료된다.

• 대한환경공학회지
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• 제29권7호
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• pp.839-845
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• 2007

용해성 glucose를 기질로 하여 혐기성 산발효조에서 동역학정수에 대한 온도의존성을 검토하였다. 온도범위는 $15^{\circ}C$에서 $30^{\circ}C$이며, 포화정수$(K_s\upsilon)$와 증식수율(Y)은 온도의 상승에 따라 감소하였지만, 최대비기질소비속도$(\upsilon_{max})$는 증가하였다. 기질소비속도와 균체 증식속도의 온도보정인자$(Q_{10})$ 값은 각각 1.3에서 2.2, 1.5에서 2.2의 범위를 보였다. 최대비기질소비속도$(\upsilon_{max})$가 증식수율(Y) 보다 온도의 변화에 대하여 더 민감하였다. $20^{\circ}C$에서 $30^{\circ}C$까지의 온도영역에서 체류시간과 기질농도의 관계에 대한 시물레이션 모델은 $1/SRT={(6.53){\cdot}(1.038)^{T-20}{\cdot}(S/X)}/{(1.38){\cdot}(0.983)^{T-20}+(S/X)}$이다.

• Journal of Microbiology and Biotechnology
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• 제30권2호
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• pp.259-270
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• 2020

Listeria monocytogenes is a gram-positive, facultative anaerobe food pathogen responsible for the listeriosis that mostly occurs during the low-temperature storage of a cold cut or dairy products. To understand the systemic response to a wide range of growth temperatures, L. monocytogenes were cultivated at a different temperature from 10℃ to 42℃, then whole cell proteomic analysis has been performed both exponential and stationary cells. The specific growth rate increased proportionally with the increase in growth temperature. The maximum growth rate was observed at 37℃ and was maintained at 42℃. Global protein expression profiles mainly depended on the growth temperatures showing similar clusters between exponential and stationary phases. Expressed proteins were categorized by their belonging metabolic systems and then, evaluated the change of expression level in regard to the growth temperature and stages. DnaK, GroEL, GroES, GrpE, and CspB, which were the heat&cold shock response proteins, increased their expression with increasing the growth temperatures. In particular, GroES and CspB were expressed more than 100-fold than at low temperatures during the exponential phase. Meanwhile, CspL, another cold shock protein, overexpressed at a low temperature then exponentially decreased its expression to 65-folds. Chemotaxis protein CheV and flagella proteins were highly expressed at low temperatures and stationary phases. Housekeeping proteins maintained their expression levels constant regardless of growth temperature or growth phases. Most of the growth related proteins, which include central carbon catabolic enzymes, were highly expressed at 30℃ then decreased sharply at high growth temperatures.

• Journal of Microbiology and Biotechnology
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• 제7권4호
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• pp.242-249
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• 1997

Stability of bioluminescence was investigated with Photobacterium phosphoreum immobilized on the strontium alginate in order to develope continuous real time monitoring of pollutants. The stability of bioluminescence emission was improved by prolonged aging time. The aging time of ${\geq}40$ min and the cell concentration of ${\leq}0.6\;of\;OD_660$ were selected for the immobilization of P. phosphoreum to give linearity between cell concentrations and bioluminescence intensity. In sensitivity tests using phenol, it was found that this compound quenched bioluminescence proportional to the concentration without lowering of cell growth. The lower value for maximum quenching ($q_s$) and higher dissociation constant ($K_s$) were observed with strontium-alginate immobilized cells compared to free cells. The response of bioluminescence to toxicants was evaluated with the immobilized luminescent bacteria. The sensitivity of the immobilized cells was found to be good in response to toxicants, 4-nitrophenol, salicylate and cadmium, when evaluated with a specific rate of bioluminescence quenching.

• 대한환경공학회지
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• 제22권1호
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• pp.11-19
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• 2000

생물학적 폐수처리장의 효율을 정확하게 예측하기 위해서는 생물학적 동력학 계수와 화학양론적 계수를 반드시 추정하여야만 한다. 본 연구에서는 생물학적 동력학 계수를 추정하는 실험적 방법과 그 이론적 배경이 논의되었다. 또한 생물학적 동력학 계수 추정을 위해 신소이용률(Oxygen Uptake Rate, OUR)을 이용한 회분식 실험을 실시하였다. 호기성 상태에서 종속영양미생물과 독립영양미생물의 생물학적 동력학 계수를 추정하기 위한 간단한 방법이 기술되어 있다. 생물학적 동력학 계수 추정시 해석상의 부정확성 때문에 COD와 VSS농도를 이용하지 않고 산소이용률을 미생물 성장 자료로 변환하여 사용하였다. 종속영양미생물의 최대비성장율, 생산계수, 반속도상수, 사멸율을 산소이용률을 사용하여 추정하였다. 또한 독립영양미생물의 최대비성장율은 $NO_3{^-}$ 농도의 증가율로부터 추정하였다. 본 연구의 목적은 회분식 반응조에서 산소이용률을 이용해 종속영양미생물과 독립영양미생물의 생물학적 동력학 계수를 정확하고 간편하게 추정하는데 있다. 이러한 산소이용률을 이용한 생물학적 동력학 계수 추정 방법이 복잡한 활성슬러지 모델링에 도움을 줄 것으로 판단된다.