• 한국환경보건학회지
• /
• 제20권2호
• /
• pp.28-38
• /
• 1994

New problems have been recently posed on the abnormal foaming (Scum) in an aeration tank and the sludge flotation in a final sedimentation tank during the activated sludge process. However, the activities of the causing bacteria, Nocardia-amarae in an aeration tank have not been searched out at all. Therefore, in this article the activities of Nocardia-amarae in an aeration tank have been closely examined by means of the changes of (F/M) ratio, SRT and inflowing substrate using continuous type and fed-batch type. Summarized results of experiments are as follows. 1. Regrading continuous culture when synthetic wastewater was used substrate neither the increase in the number of Nocardia-amarae in the aeration tank nor the Occurrence of Scum was observed. 2. In the case of fed-batch culture, Nocardia-amarae in the aeration tank increased due to the partial change in substrate and the effect of SRT was significant. 3. Once the scum was formed and the quantity of added Nocardia-amarae and substrate were not changed, the effect of STR was not significant.

• KSBB Journal
• /
• 제23권5호
• /
• pp.449-451
• /
• 2008

Saccharomyces cerevisiae를 배양하여 ceramide를 생산하였다. 각기 다른 growth phase에서의 ceramide 생산량을 비교 실험하였다. Ceramide는 ELSD가 장착된 HPLC를 통하여 분석하였으며 stationary phase에 접어든 후 12시간 후에 회수, 추출된 양(2.01 mg ceramide/g cell)이 최대인 것으로 나타났다.

• Mycobiology
• /
• 제42권3호
• /
• pp.305-309
• /
• 2014

We investigated a novel process for production of ethanol from glycerol using the yeast Pachysolen tannophilus. After optimization of the fermentation medium, repeated-batch flask culture was performed over a period of 378 hr using yeast cells immobilized on Celite. Our results indicated that the use of Celite for immobilization of P. tannophilus was a practical approach for ethanol production from glycerol, and should be suitable for industrial ethanol production.

• Journal of Microbiology and Biotechnology
• /
• 제8권6호
• /
• pp.575-580
• /
• 1998

Cellulase production by batch culture using the Trichoderma reesei Rut C30 strain with various concentrations of Solka Floc with 1 % wheat bran was studied in a 2.5 I fermenter. The cellulase activity increased with Solka Floc concentration up to 5%. When 5% Solka Floc and 1% wheat bran were contained in the medium, carboxymethyl cellulose (CMC) and filter paper (FP) activities were 232.4 U/$m\ell$ and 21.25 U/$m\ell$, respectively. The productivity was 143.6 FPU $1^{-l}h^{-1}$ and the yield was 425 FPU/g. The colonial morphology of T. reesei Rut C30 grown on Avicel agar plates and the changes in mycelial morphology of T. reesei Rut C30 with culture time are also presented.

• Journal of Microbiology and Biotechnology
• /
• 제13권5호
• /
• pp.641-646
• /
• 2003

An accurate and efficient method for measuring the mass of hairy roots using conductometry is established. A conductivity equation expressed in terms of the concentration of the ion species in the medium is suggested. By using this equation, the effect of the individual ions on the total conductivity can be quantitatively analyzed. An equation for the in situ estimation of the cell growth coefficient for determining the mass of hairy roots is established based on measurements of the nitrogen concentration and conductivity during cultivation. The proposed equation does not require preliminary experiments to determine the cell growth coefficient. Instead, the physiological characteristics of the plant species are reflected by introducing the cellular nitrogen content. Since the cell growth coefficient is determined by measuring the major ionic nutrient concentrations, it is more effective to express the dynamics of an actual culture system. This improved method for determining the mass of hairy roots was successfully utilized in a fed-batch culture system.

• 한국지하수토양환경학회:학술대회논문집
• /
• 한국지하수토양환경학회 2003년도 추계학술발표회
• /
• pp.454-457
• /
• 2003

A new approach for groundwater treatment combines a permeable Fe(0) barrier to breakdown higher chlorinated solvents like PCE and TCE with a downgradient aerobic biological treatment system to biotransform less chlorinated solvents, such as DCE and vinyl chloride (VC). The expected bacterial performance downgradient of an Fe(0) barrier was evaluated through laboratory batch experiments with a toluene-degrading mixed culture that cometabolically transforms cis-1,2-DCE and VC. The amount of cis-1,2-DCE (initially at 2,000 ppb) and VC (initially at 2,000 ppb) transformed was controlled by the initial toluene (20,000 ppb) concentration. VC was removed much more effectively than Cis-1,2-DCE, and a higher toluene concentration in comparison to the co-substrate concentrations was needed for complete co-substrate removal. Overall, the coupling of an Fe(0) barrier and subsequent biodegradation appears feasible for remediation of complex mixtures of chlorinated solvents and petroleum hydrocarbons in groundwater

• Journal of applied mathematics & informatics
• /
• 제24권1_2호
• /
• pp.387-397
• /
• 2007

According to the controllability of pulse times and the amount of jumps in the states at these times in the process of fed-batch culture producing 1,3-propanediol, this paper proposes a terminal optimal control model, whose constraint condition is the nonlinear impulsive delay system. The existence of optimal control is discussed and an optimization algorithm which is applied to each subinternal over one cycle for this optimal control problem is constructed. Finally, the numerical simulations show that the terminal intensity of producing 1,3-propanediol has been increased obviously.

• KSBB Journal
• /
• 제6권1호
• /
• pp.15-25
• /
• 1991

The optimal glucose concentration for the high-density culture of recombinant yeasts was obtained using dynamic simulation. An adaptive and predictive algoritilm complimented by the rule base was proposed for the control of the fed-batch fermentation process. The measurement of process variables has relatively long sampling period and relatively long time delay characteristics. As one of the solution on these problems, prediction techniques and rule bases were added to a classical recursive identification and control algorithm. Rule bases were used in the determination of control input considering the difference between the predicted value and the measured value. A mathelnatical model was used in the estimation and interpretation of the changes of state variables and parameters. Better performances were obtained by employing the control algorithm proposed in the present study compared to the conventional adaptive control method.

• KSBB Journal
• /
• 제19권6호
• /
• pp.451-456
• /
• 2004

교반배양시 배지에 첨가되는 에탄올의 농도가 증가할수록 $Cel^-$ mutant의 발생율이 증가하므로 $1.5\%$ 에탄올이 첨가된 배지의 경우 500 rpm보다 높은 교반속도를 유지해야 효과적으로 $Cel^-$ mutant의 발생이 억제되고 BC 생산량을 증가시킬 수 있다. 교반 배양과 같은 강한 shear stress의 배양환경 하에서는 진탕배양의 경우와 달리 $1.0\%$ 에탄올을 분할공급하더라도 BC 생산의 효율성을 높일 수 없었다. Phosphate ion이 첨가된 배지보다 첨가되지 않은 배지에서 BC 생산량이 더 높았다. 배지조성 중 아세트산의 농도를 $1.0\%$로 증가시키면 균체의 건조중량은 변화가 없었으나 BC 생산량이 감소되었다. 배양액의 pH 제어는 BC의 생산에는 영향을 미치지 않았으나 균체의 성장과 WSPS의 생산을 향상시켰다.

• 한국미생물·생명공학회지
• /
• 제21권4호
• /
• pp.354-365
• /
• 1993

A novel control method with automatic tuning of PID controller parameters has been developed for efficient regulation of dissolved oxygen concentration in fed-batch fermentations of Escherichia coli. Agitation speed and oxygen partial pressure in the inlet gas stream were chosen to be the manipulated variables. A heuristic reasoning allowed improved tuning decisions from the supervision of control performance indices and it coule obviate the needs for process assumptions or disturbance patterns. The control input consisted of feedback and feedforword parts. The feedback part was determined by PID control and the feedforward part is determined from the feed rate. The proportional gain was updated on-line by a set of heuristics rules based on the supervision of three performance indices. These indices were output error covariance, the average value of output error, and input covariance, which were calculated on-line using a moving window. The integral and derivative time constants were determined from the period of output response. The specific growth rate was maintained at a low level to avoid acetic acid accumulation and thus to achieve a high cell density. The specific growthe rate was estimated from the carbon dioxide evolution rate. In fed-batch fermentation, the simutaneous control of dissolved oxygen concentration (at 0.2; fraction of saturated value) and specific growth rate (at 0.25$hr^{-1}$) was satisfactory for the entire culture period in spite of the changes in the feed rate and the switching of control input.