• Journal of Microbiology and Biotechnology
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• 제14권6호
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• pp.1163-1169
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• 2004

An unstructured mathematical model is presented for lactic acid fermentation based on the energy balance. The proposed model reflects the energy metabolic state and then predicts the cell growth, lactic acid production, and glucose consumption rates by relating the above rates with the energy metabolic rate. Fermentation experiments were conducted under various initial lactic acid concentrations of 0, 30, 50, 70, and 90 g/l. Also, a genetic algorithm was used for further optimization of the model parameters and included the operations of coding, initialization, hybridization, mutation, decoding, fitness calculation, selection, and reproduction exerted on individuals (or chromosomes) in a population. The simulation results showed a good fit between the model prediction and the experimental data. The genetic algorithm proved to be useful for model parameter optimization, suggesting wider applications in the field of biological engineering.

• 한국미생물·생명공학회지
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• 제22권5호
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• pp.531-537
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• 1994

This study was undertaken with objective of optimizing the conditions of fermentation in an aqueous two-phase system which is composed of polyethylene glycol (PEG) 20000 and crude dextran (Dx). The data were obtained and analyzed using the Box-Wilson's experimental design protocol and the response surface methodology. To reach this end a multilinear polynomial regres- sion model was developed, which can be utilized for the purpose of optimizing the extractive fermentation. Optimum conditions for batch fermentation with aqueous two phase system were found to be at 4.2~5.4% PEG/3.2~4.2% Dx range. The composition of the center was 4.8% PEG/ 3.6% Dx. Optimum operating conditions for initial sugar concentration and fermentation time were approximately 160 g/l, and 21~22 hr, respectively. Fermentation in the aqueous two phase system composed of 5% PEG/4% Dx showed increase of 23% in ethanol concentration, of 9.5% in ethanol yield, and of 19% in ethanol productivity as compared to the case of fermentation of neat Jerusalem artichoke juice.

• Korean Chemical Engineering Research
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• 제52권3호
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• pp.402-406
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• 2014

본 실험에서는 농부산물인 밀짚을 고체배지로 사용하여 Aspergillus niger NRRL 567에서 구연산 생산 시, 발효조건과 첨가제가 구연산 생산에 미치는 영향을 단일변수(one-factor-at-a-time) 최적화를 이용하여 주요 인자의 순차적 최적화를 수행하였다. 발효 72시간에서 온도, 수분함량, 입자크기, pH와 첨가제 농도를 최적화했을 때, 각각 $30^{\circ}C$, 70%, 0.5~1.0 mm, pH 5.5와 4% 메탄올 첨가조건에서 최대 구연산 생산인 206.0 g/kg 건조중량 (DM)을 확인할 수 있었다. 이는 최적화 이전 구연산 최고 생산인 74.5 g/kg DM 대비 177% 증가한 결과이다. 최적화 실험에서 도출된 조건을 밀짚, 옥수수대와 피트모스(peat moss)에 적용하여 고체발효를 수행하였을 때, 발효 120시간에서 각각 231.8, 213.8, 240.2 g/kg DM 구연산 생산을 확보하였다. 본 실험 결과는 밀짚과 옥수수대 등의 목질계 농부산물을 이용한 구연산 생산 시, 고체발효법이 기존의 액체발효법의 대체가 가능함을 시사하였다.

• Journal of Microbiology and Biotechnology
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• 제32권7호
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• pp.902-910
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• 2022

The ginsenoside compound K (C-K) is widely used in traditional medicines, nutritional supplements, and cosmetics owing to its diverse pharmacological activities. Although many studies on C-K production have been conducted, fermentation is reported to produce C-K with low concentration and productivity. In the present study, addition of an inducer and optimization of the carbon and nitrogen sources in the medium were performed using response surface methodology to increase the C-K production via fermentation by Aspergillus tubingensis, a generally recognized as safe fungus. The optimized inducer and carbon and nitrogen sources were 2 g/l rice straw, 10 g/l sucrose, and 10 g/l soy protein concentrate, respectively, and they resulted in a 3.1-fold increase in the concentration and productivity of C-K (0.22 g/l and 1.52 mg/l/h, respectively) compared to those used before optimization without inducer (0.071 g/l and 0.49 mg/l/h, respectively). The feeding methods of American ginseng extract (AGE), including feeding timing, feeding concentration, and feeding frequency, were also optimized. Under the optimized conditions, A. tubingensis produced 3.96 mM (2.47 g/l) C-K at 144 h by feeding two times with 8 g/l AGE at 48 and 60 h, with a productivity of 17.1 mg/l/h. The concentration and productivity of C-K after optimization of feeding methods were 11-fold higher than those before the optimization (0.22 g/l and 1.52 mg/l/h, respectively). Thus, the optimization for the feeding methods of ginseng extract is an efficient strategy to increase C-K production. To our knowledge, this is the highest reported C-K concentration and productivity via fermentation reported so far.

• Korean Chemical Engineering Research
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• 제52권3호
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• pp.302-306
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• 2014

목질계 분해효소 활성 증대를 위해 밀짚을 이용한 고체발효에서 주요 발효인자의 최적화를 수행하였다. Trichoderma reesei와 Aspergillus niger를 이용한 혼합배양에서 고체발효에 주요한 영향을 미친다고 알려진 배양온도, pH, 수분함량과 고체기질 크기를 순차적 최적화를 진행하였다. 실험에 적용 된 인자 모두 목질계 분해효소 활성에 유의한 효과를 주었으며, 발효온도 $40^{\circ}C$, pH 7, 수분함량 75%와 고체기질 크기 0.25~0.5 mm가 목질계 분해효소 생산을 위한 최적 조건임을 알 수 있었다. 최적조건 하에서 밀짚을 이용한 고체발효를 수행하였을 때, 효소활성 기준 cellulase 10.3 IU, endoglucanase 100.3 IU, ${\beta}$-glucosidase 22.9 IU와 xylanase 2261.7 IU/g dry material을 배양 96시간에 확인할 수 있었다. 본 결과는 기존 효소활성 대비 각각 72.6, 48.7, 55.2와 51.9% 증가한 수치로 혼합배양과 순차적 최적화를 적용하여 효과적인 목질계 분해효소 활성 증대가 가능함을 확인하였다.

• 한국식품영양학회지
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• 제21권4호
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• pp.391-396
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• 2008

In this study, we attempted to optimize the fermentation processes in the production of lactic acid juice with 20% Maesil(Prunus mume) extract using Lactobacillus plantarum isolated from Kimchi, assessing a variety of pH, temperature, sugar compositions, and sugar concentrations. In the preparation of fermented Maesil(Prunus mume) extract, the optimal pH and fermentation temperature were 4.0 and $35^{\circ}C$, respectively. When the effects of various sugar sources and concentrations on lactic acid fermentation were assessed, 15% fructose was shown to yield more acid productivity than was observed with other sugar sources. The optimum composition, on the basis of our sensory evaluations, was determined to be a fructose concentration of 15% and a fermentation time of $72{\sim}96$ hours.

• Biotechnology and Bioprocess Engineering:BBE
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• 제5권4호
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• pp.275-287
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• 2000

Fermentation strategies for recombinant protein production in Pichia pastoris have been investigated and are reviewed here. Characteristics of the expression system, such as phenotypes and carbon utilization, are summarized. Recently reported results such as growth model establishment, app58lication of a methanol sensor, optimization of substrate feeding strategy, DOstat controller design, mixed feed technology, and perfusion and continuous culture are discussed in detail.

• Journal of Applied Biological Chemistry
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• 제56권2호
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• pp.119-129
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• 2013

Thirteen different Streptomyces isolates were evaluated for their ability to produce keratinase using chicken feather as a sole carbon and nitrogen sources under solid state fermentation (SSF). Streptomyces sp. NRC 13S produced the highest keratinase activity [1,792 U/g fermented substrate (fs)]. The phenotypic characterization and analysis of 16S rDNA sequencing of the isolate were studied. Optimization of SSF medium for keratinase production by the local isolate, Streptomyces sp. NRC13S, was carried out using the one-variable-at-a-time and the statistical approaches. In the first optimization step, the effect of incubation period, initial moisture content, initial pH value of the fermentation medium, and supplementation of some agro-industrial by-products on keratinase production were evaluated. The strain produced about 2,310 U/gfs when it grew on chicken feather with moisture content of 75% (w/w), feather: fodder yeast ratio of 70:30 (w/w), and initial pH 7 using phosphate buffer after 8 days. Based on these results, the Box-Behnken design and response surface methodology were applied to find out the optimal conditions for the enzyme production. The corresponding maximal production of keratinase was about 2,569.38 U/gfs.

• 한국초지조사료학회지
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• 제32권4호
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• pp.361-368
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• 2012

The present study was conducted to develop persimmon peel, a by-product of dried persimmon manufacturing, as a feed additive via lactic acid bacteria fermentation. Pediococcus pentosaceus, Lactobacillus plantarum, and three strains of Leuconostoc mesenteroides were used as a starter culture in the solid state fermentation of persimmon peel, and antioxidant activity and total polyphenol content were assessed. Leuconostoc mesenteroides KCTC 3100 showed high antioxidant activity (p<0.05), whereas Pediococcus pentosaceus showed high total polyphenol content (p<0.05). These two strains were thus selected as starter culture strains. Glucose, sucrose and molasses were used as variables for optimization and a total 15 experimental runs were produced according to Box-Behnken design. Regarding significant effects of variables, molasses showed linear and square effects on antioxidant activity of persimmon peel fermentation (p<0.05). In conclusion, optimum concentrations of glucose, sucrose, and molasses were determined to be 4.2, 3.9 and 5.3 g/L, respectively, using a response surface model. Antioxidant activity was also improved 2.5 fold after optimization.

• Food Science and Biotechnology
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• 제17권5호
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• pp.904-911
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• 2008

Covalent cross-links between a number of proteins and peptides explain why transglutaminase may be widely used by food processing industries. The objective of this work was optimization of the fermentation process to produce transglutaminase from a new microbial source, the Streptomyces sp. P20. The strategy adopted to modify the usual literature media was: (1) fractional factorial design (FFD) to elucidate the key medium ingredients, (2) central composite design (CCD) to optimise the concentration of the key components. Optimization of the medium resulted in not only an 86% increase in microbial transglutaminase activity as compared to the media cited in the literature, but also a reduction in the production cost. Optimal fermentation conditions - namely temperature and agitation rate - were also studied, using CCD methodology. Usual conditions of $30^{\circ}C$ and 100 rpm were within the optimal area. All other parameters for enzyme production were experimentally proven to be optimum fermentation conditions.