• Membrane and Water Treatment
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• 제11권1호
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• pp.79-85
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• 2020

A single-stage deammonification with a sequencing batch reactor (SBR) that simultaneous nitritation, anaerobic ammonia oxidation (anammox), and denitrification (SNAD) occur in one reactor has been widely applied for sidestream of wastewater treatment plant. For the stable and well-balanced SNAD, a feeding strategy of influent wastewater is one of the most important operating factors in the single-stage deammonification SBR. In this study, single-stage deammonification SBR (working volume 30L) was operated to treat a high-strength ammonium wastewater (1200 mg NH₄⁺-N/L) with different feeding strategies (single feeding and nine-step feeding) under the condition without COD. Each cycle of the step feeding involved 6 sub-cycles consisted of aerobic and anoxic periods for partial nitritation (PN) and anammox, respectively. Contrary to unstable performance in the single feeding, the step feeding showed better deammonification performance (0.565 kg-N/m³/day). Under the condition with COD, however, the nitrogen removal rate (NRR) decreased to 0.403 kg-N/m³/day when the Nine-step feeding strategies had an additional denitrification period before sub-cycles for PN and anammox. The NRR was recovered to 0.518 kg-N/m³/day by introducing an enhanced multiple-step feeding strategy. The strategy had 50 cycles consisted of feed, denitrification, PN, and anammox, instead of repeated sub-cycles for PN and anammox. The multiple-step feeding strategy without sub-cycle showed the most stable and excellent deammonification performance: high nitrogen removal efficiency (98.6%), COD removal rate (0.131 kg-COD/m³/day), and COD removal efficiency (78.8%). This seemed to be caused by that the elimination of the sub-cycles might reduce COD oxidation during aerobic condition but increase the COD utilization for denitrification period. In addition, among various sensor values, the ORP pattern appeared to be applicable to monitor and control each reaction step for deammonification in the multiple-step feeding strategy without sub-cycle. Further study to optimize the number of multiple-step feeding is still needed but these results show that the multiple-step feeding strategy can contribute to a well-balanced SNAD for deammonification when treating high-strength ammonium wastewater with COD in the single-stage deammonification SBR.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2001년도 추계학술발표대회
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• pp.333-335
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• 2001

A simple control strategy of DO-stat was introduced to the recombinant rGuamerin production process in Pichia pastoris. This induction strategy consisted of two interrelated control loops ‘by which oxygen ratio of inlet gas and methanol feeding rate was controlled. Using this control strategy, over-feeding or under-feeding of methanol could be avoided in concomitance with the efficient control of dissolved oxygen level. As a result, the cell concentration reached 130 g/L and rGuamerin expression level was 450 iu/L, which was more than 40% increased result comparing with the fed-batch process using manual control of methanol feeding rate.

• Journal of Microbiology and Biotechnology
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• 제25권2호
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• pp.185-195
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• 2015

Glucoamylase is an important industrial enzyme. Glucoamylase production by industrial Aspergillus niger strain featured with two major problems: (i) empirical substrate feeding methods deteriorating the fermentation performance; and (ii) the high raw materials cost limiting the economics of the glucoamylase product with delegated specification. In this study, we first proposed a novel three-stage varied-rate substrate feeding strategy for efficient glucoamylase production in a 5 L bioreactor using the standard feeding medium, by comparing the changing patterns of the important physiological parameters such as DO, OUR, RQ, etc., when using different substrate feeding strategies. With this strategy, the glucoamylase activity and productivity reached higher levels of 11,000 U/ml and 84.6 U/ml/h, respectively. The performance enhancement in this case was beneficial from the following results: DO and OUR could be controlled at the higher levels (30%, 43.83 mmol/l/h), while RQ was maintained at a stable/lower level of 0.60 simultaneously throughout the fed-batch phase. Based on this three-stage varied-rate substrate feeding strategy, we further evaluated the economics of using alternative carbon sources, attempting to reduce the raw materials cost. The results revealed that cornstarch hydrolysate could be considered as the best carbon source to replace the standard and expensive feeding medium. In this case, the production cost of the glucoamylase with delegated specification (5,000 U/ml) could be saved by more than 61% while the product quality be ensured simultaneously. The proposed strategy showed application potential in improving the economics of industrial glucoamylase production.

• KSBB Journal
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• 제13권6호
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• pp.681-686
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• 1998

5L 발효기에서 글루코스의 투입방법과 배지의 초기 글루코스 농도에 따른 유가식 배양에 의한 S. marcescens의 증식에 미치는 영향에 대해서 연구하였다. 발효기 조건을 일정하게 유지시켜준 각 유가식 배양에서의 최종란체량이 회분식배양에 비해서 훨씬 높았으며, 유기식 배양종에서도 기질인 글루코스의 공급을 달리하였을 때, 최종균체량에서 차이를 나타내었다. 회분식 배양과 유가식 배양중에서 글루코스의 일정비율공급밤법, 글루코스 결핍상태에서의 일정비율공급방법 그리고 지수적 공급방법의 최종균체량은 1.40, 5.07, 6.93 및 7.60g/L 이고, 그 때의 배양시간은 40, 41. 24 및 40hr이었다. 그리고 균체 생산성은 0.035, 0.124, 0.239 및 0.1909/L.h 이었다. 최종 균체량만을 가지고 비교하였올 경우에는 유가식 배양줌에서 지수적 공급방법이 가장 효율적이지만 당위시간당 균체 생산성에서는 글루코스 결핍 상태에서의 일정비율공급방법이 1.52배 정도 높게 나타냈으므로 가장 효과적인 배양 방법임을 알 수 있다. 용존산소와 글루코스 루입시가의 상관관계에서 나타난 바와 같이 글루코스 결핍상태에서 일정비율로 공급한 방법과 지수적으로 공급한 방법에서 좋은 일치를 보여주었다.

• 한국양식학회지
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• 제20권1호
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• pp.56-59
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• 2007

Effect of dietary nutrient composition on growth and body composition of juvenile olive flounder Paralichthys olivaceus with different feeding strategy was determined. Twenty-five fish averaging 16 g were randomly distributed into 12, 180 L flow-through tank each. Four treatments in triplicates were prepared: fish were fed to satiation twice daily by the control diet for 8 weeks as the control group (Con) and fish were fed to satiation twice daily by the control and high nutrient diets for 6 weeks after 2-week fasting (2WS-6WFC, 2WS-6WFHN, respectively) and finally, fish were fed to satiation twice daily by the high nutrient diet for the consecutive 3 days after 4-day fasting for 8 weeks (4DS-3DFHN). No significant difference was found in either survival or weight gain of flounder among treatments. Feed efficiency ratio (FER) for fish in the 2WS-6WFHN treatment was significantly higher than that for fish in the Con and 2WS-6WFC treatments. Protein efficiency ratio (PER) of fish in the 2WS-6WFHN and 4DS-3DFHN treatments was significantly higher than that of fish in the 2WS-6WFC treatment. In conclusion, manipulation of dietary nutrient composition and/or feeding strategy can effectively improve growth of juvenile olive flounder without growth retardation at restricted feeding regime.

• 한국환경과학회지
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• 제27권6호
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• pp.447-456
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• 2018

In this research, the target process was a modified type of a conventional aeration tank with four different influent feeding points and alternated aeration to obtain nitrogen removal. For more accurate switching of influent feeding, the process was operated under a designed control strategy based on monitoring of $NH_4-N$ and $NO_X-N$ concentrations in the tank. However, the strategy did have some limitations. For example, it was not sensitive to detecting the end of each reaction when losing the balance between nitrification and denitrification of each opposite part of biological tank. To overcome the limitations of the existing control strategy, a diagnosis-based control strategy was suggested in this research using the diagnosis results classified as normal (N), ammonia accumulation (AA) and nitrate accumulation (NA). Using the pre-designed rules for control actions, the aeration and volume of the aerated part of the reactor could be increased or decreased at a fixed mode time. In simulations of the suggested diagnosis-based control strategy, the $NH_4-N$ and $NO_X-N$ removal rates in the reactor were maintained at higher levels than those of the existing control strategy.

• Journal of Microbiology and Biotechnology
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• 제28권2호
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• pp.293-297
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• 2018

Controlling the residual glucose concentration is important for improving productivity in $\text\tiny{L}$-threonine fermentation. In this study, we developed a procedure to automatically control the feeding quantity of glucose solution as a function of ammonia-water consumption rate. The feeding ratio ($R_{C/N}$) of glucose and ammonia water was predetermined via a stoichiometric approach, on the basis of glucose-ammonia water consumption rates. In a 5-L fermenter, 102 g/l $\text\tiny{L}$-threonine was obtained using our glucose-ammonia water combined feeding strategy, which was then successfully applied in a 500-L fermenter (89 g/l). Therefore, we conclude that an automatic combination feeding strategy is suitable for improving $\text\tiny{L}$-threonine production.

• Journal of Microbiology and Biotechnology
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• 제29권4호
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• pp.587-595
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• 2019

Pharmacological research on (CHA), a marine-derived quinazolinone alkaloid with significant cytotoxic activity, is restricted by low yields and is a problem that needs to be settled urgently. In this work, the selection of additional nitrogen sources and the optimization of additional concentrations and longer fermentation times using ammonium acetate, were investigated. CHA production was optimized to 62.1 mg/l with the addition of 50 mM ammonium acetate at 120 h of the fermentation in the shaker flask. This feeding strategy significantly increased 3-deoxy-arabino-heptulosonate-7-phosphate synthase activity and transcript levels of critical genes (laeA, dahp, and trpC) in the shikimate pathway compared with the non-treatment group. In addition, the selection of the feeding rate (0.01 and $0.03g/l{\cdot}h$) was investigated in a 5-L bioreactor. As a result, CHA production was increased by 57.9 mg/l with a $0.01g/l{\cdot}h$ ammonium acetate feeding rate. This work shows that the strategy of ammonium acetate supplementation had an effective role in improving CHA production by Aspergillus fumigatus CY018. It also shows that this strategy could serve as an important example of large-scale fermentation of a marine fungus in submerged culture.

• Clinical and Experimental Pediatrics
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• 제59권12호
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• pp.466-470
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• 2016

Early, aggressive nutrition is an important contributing factor of long-term neurodevelopmental outcomes. To ensure optimal growth in premature infants, adequate protein intake and optimal protein/energy ratio should be emphasized rather than the overall energy intake. Minimal enteral nutrition should be initiated as soon as possible in the first days of life, and feeding advancement should be individualized according to the clinical course of the infant. During hospitalization, enteral nutrition with preterm formula and fortified human milk represent the best feeding practices for facilitating growth. After discharge, the enteral nutrition strategy should be individualized according to the infant's weight at discharge. Infants with suboptimal weight for their postconceptional age at discharge should receive supplementation with human milk fortifiers or nutrient-enriched feeding, and the enteral nutrition strategy should be reviewed and modified continuously to achieve the target growth parameters.

• KSBB Journal
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• 제13권3호
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• pp.259-267
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• 1998

Optimal feeding strategies in bioreactor operation of Scutellaria baicalensis G. plant cell culture were investigated to maximize the production of flavone glycosides by using a structured kinetic model which can predict culture growth and flavone glycosides synthesis in a rigorous, quantitative manner. For the production of baicalin and wogonin-7-0-GA, the strategies for glucose feeding into Scutellaria baicalensis G. plant cell culture were proposed based on the model, which are a periodic fed-batch operation with maintenance of cell viability and of specific production rate respectively, and a perfusion operation with maintenance of specific production rate for baicalin and wogonin-7-0-GA. Simulation results showed that the highest volumetric concentration of flavone glycosides was obtained in a periodic fed-batch operation with maintenance of cell viability among all the suggested strategies. In the periodic fed-batch operations, the higher volumetric production of flavone glycosides was achieved compared with that in the perfusion operation. It can be concluded that a periodic fed-batch operation with maintenance of cell viability would be the optimal and practical operating strategy of Scutellaris baicalensis G. plant cell culture for the production of flavone glycosides.