• Journal of Microbiology and Biotechnology
• /
• 제16권12호
• /
• pp.1849-1855
• /
• 2006

It has been shown that the initial conditions of bacterial cultivation are extremely important for the successful production of hyaluronic acid (HA) by fermentation. We investigated several parameters that affect cell growth rate and the productivity and molecular weight of hyaluronic acid--i.e., agitation speed, aeration rate, culture temperature, pH, and pressure--to determine how to optimize the production of HA by Streptococcus zooepidemicus on an industrial scale. Using a 30-1 jar fermentor under laboratory conditions, we achieved maximum HA productivity and biomass when the agitation speed and aeration rate were increased simultaneously. By shifting the temperature downward from 35$^{\circ}C$ to 32$^{\circ}C$ at key levels of cell growth during the fermentation process, we were able to obtain HA with a molecular weight of $2.8{\times}10^6$ at a productivity of 5.3 g/l. Moreover, we reproduced these optimized conditions successfully in three 30-1 jar fermentors. By reproducing these conditions in a 3-$m^3$ fermentor, we were able to produce HA with a molecular weight of $2.9{\times}10^6$ at a productivity of 5.4 g/l under large-scale conditions.

• Journal of Microbiology and Biotechnology
• /
• 제7권4호
• /
• pp.262-266
• /
• 1997

To increase the high production of 1-deoxynojirimycin (DNJ) from Streptomyces sp. SID9135, the effect of various carbon sources, nitrogen sources, cationic metal ions, the initial pH of the medium, and agitation speed were investigated. The most effective carbon and nitrogen sources were found to be lactose 2.5% (w/v) and soybean meal 2.0% (w/v), respectively. None of the cationic metal ions examined had any detectable stimulating effect on DNJ production except $Fe^{+2}$ ion. The initial optimum pH for DNJ production ranged from 6-8 and agitation speed was most effective at 400 rpm. In the jar fermentor experiments under optimal culture conditions, the accumulation of DNJ reached about $640{\mu}g$/ml after 5 days of cultivation and the level remained the same for a further two days.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2001년도 The 6th International Symposium of East Asian Resources Recycling Technology
• /
• pp.342-348
• /
• 2001

This study was conducted to obtain granular crystalline gypsum that can be used as raw material for plaster boards or cements from waste Plaster board. We could disintegrate preferentially gypsum to gypsum needle in 10${\mu}{\textrm}{m}$ or less size among the contents of waste plaster board (gypsum, paper, fiber, and inorganic material .etc.) by hydration afterwards the dehydration of crushed waste plaster board. In this case, the optimum conditions for minimizing the size of gypsum were dehydration rate of 75%~ 85%, hydration concentration of 10~20%, agitation speed of 250~400rpm, crushing size of 2cm or less. Gypsum of 98.21% grade was recovered with 99.0% yield from under screenings of 325mesh wet screening which followed by the dehydration-hydration process performed in the conditions of dehydration rate of 80%, hydration concentration of 15%, agitation speed of 300rpm, crushing size of 2cm or less. Subsequently, Plate-like Crystalline gypsum of is 151${\mu}{\textrm}{m}$ size and the grade of 99.49% with the Yield of 98.0% from the upper screenings of 270mesh wet screening carried out after the re-crystallization of the recovered gypsum needle slurry.

• KSBB Journal
• /
• 제5권3호
• /
• pp.307-313
• /
• 1990

배양기와 16비트 마이크로컴퓨터를 접속하여 호기성 미생물의 고농도 유가배양시스템을 구성하였다. 기질공급을 위한 제어변수로는 용존산소(DO)를 이용하였다. 용존산소측정기의 출력신호를 컴퓨터에 입력시켜 측정한 DO값에 근거하여 교반모터의 교반속도와 산소유량을 제어함으로써 배양액의 DO를 일정하게 유지하였으며, 연동펌프의 제어에 의해 기질공급을 안정하게 수행하였다. 기질공급의 제어와 DO의 제어를 한가지의 하아드웨어 및 소프트 웨어로 수행할 수 있었다. 제어시스템을 이용하여 메탄올이용균인 Methylobacillus sp. SKI을 유가배양한 결과 배양액의 DO제어와 메탄올 공급의 제어가 무리없이 수행되었으며, 배양 10시간만에 16.53g/l의 균체농도에 도달하였다.

• 한국염색가공학회지
• /
• 제7권2호
• /
• pp.32-39
• /
• 1995

Various grades of hydroxyethyl cellulose (HEC, MS 0.65-3.20) were prepared throngh reaction of the knit-cotton-waste with ethylene oxide(EO). The knit-cotton-waste was composed of 98% of $\alpha$-cellulose and 2% of other components, and the cellulose was highly pure. The molar ratio of EO to knit-cotton-waste and that of NaOH to knit-cotton-waste, and the agitation speed were the important factors determining the molar substitution(MS) during the preparation of HEC. The MS of HEC was remarkably increased with increasing molar ratio of EO' to knit-cotton-waste. When the molar ratio of EO to knit-cotton-waste was 3.5, that of NaOH to knit-cotton-waste was 1.25, and agitation speed was 450rpm, it was possible to prepare HEC of MS 2.5. The structure and crystallinity of HECs prepared were determined by FT-IR and X-ray diffraction.

• 공업화학
• /
• 제5권2호
• /
• pp.223-229
• /
• 1994

회분식 추출기를 이용하여 구연산-초산 혼합수용액-n-butylacetate계에서 2급 아민 추출제인 DITDA와 용매화 추출제인 MOHPO를 이용 추출시 물질전달계수에 미치는 교반속도의 영향에 대하여 연구하였다. 실험결과 본 추출장치에서 교반속도가 커질수록 추출도는 증가하였고, 교반속도가 200rpm, 교반시간 30분 정도가 가장 좋은 결과를 얻었다. 또한 구연산-초산 혼합수용액에서 추출제로 2급 아민인 DITDA을 사용했을 경우 추출도가 더 높았다. 물질전달계수는 추출도와 비례함을 알았고, 구연산을 DITDA로 추출시 추잔상측 물질전달계수와 Re수와는 $K_r=1.254{\times}10^{-3}Re^{0.536}$이었다.

• 자원리싸이클링
• /
• 제10권6호
• /
• pp.43-52
• /
• 2001

This study was conducted to obtain granular crystalline gypsum that can be used as raw material for Plaster boards or cements from waste Plaster board. Gypsum could be Preferentially disintegrated to gypsum needle in $10\mu\textrm{m}$ or less size by hydration after the dehydration of crushed waste Plaster board. The finer the gypsum needle, it is easier to remove coarse impurities and to recover the gypsum needle. The optimum conditions for obtain the finer gypsum size were dehydration rate of 75~85%, solid concentration at hydration of 10~15%, agitation speed of 250~400 rpm, crushing size before dehydration of 2 cm or less. Gypsum of 98.21% grade was recovered with 99.0% yield as the undersize of 325 mesh wet screening followed by the dehydration-hydration process performed at the conditions of dehydration rate of 80%, solid concentration at hydration of 15%, agitation speed of 300 rpm, crushing size before dehydration of 2 cm or less. After the recrystallization of recovered gypsum, Plate-like gypsum of $151\mu\textrm{m}$ size with 99.49% grade was obtained as the oversize of 270 mesh in a wet screening.

• Macromolecular Research
• /
• 제11권2호
• /
• pp.104-109
• /
• 2003

A microcellular, which combines a rubber with the conventional formulation of styrene/divinylbenzene/sorbitan monooleate/water system, was prepared using high internal phase emulsion (HIPE) polymerization. Although the open microcellular foam with low density from the conventional HIPE polymerization shows highly porous characteristics with fine, regular and isotropic structure, the one having much smaller cell size is desirable for various applications. In this study, a polybutadiene was introduced to reduce the cell size with comparable properties. Major interests were focused on the effects of rubber concentration and agitation speed on the cell sizes and compression properties. Scanning electron microscopy was used to observe the microcellular morphology and compression tests were conducted to evaluate the stress-strain behaviors. It was found that the cell size decreased as rubber concentration increased, reflecting a competition between the higher viscosity of continuous phase and the lower viscosity ratio of dispersed to continuous phases due to the addition of high molecular weight rubber into the oil phase of emulsion. A correlation for the average cell size depending on agitation speed was attempted and the result was quite satisfactory.

• KSBB Journal
• /
• 제5권1호
• /
• pp.25-35
• /
• 1990

In the Xanthan gum fermentation by Xanthomonas campestris there are problems of the large energy consumption by long fermentation time, the mass transfer of oxygen and nutrients by high viscous fermentation broth. In this study, the media optimization and the fed batch fermentation were carried out to decrease fermentation time and increase Xanthan gum yield. The $O_2$ uptake rate (OUR) and $CO_2$ evolution rate(CER) which were obtained from the analysis of fermentation exit gas using a gas chromatograph were investigated. As a result, the fermentation time decreased at optimal assimilable nitrogen concentration but increased at poor or rich assimilable nitrogen concentration, the Xanthan gum biosynthesis was stimulated under the limited condition of assimilable nitrogen source and the optimum fermentation medium was obtained as follow; Glucose=30g / l, Peptone=8.0g / l, $K_2HPO_4=2.0g/l$, $MgS0_47H_2O=10g/l$, Sodium acetate=20g/l, Sodium pyruvate=0.5g/1. As the agitation speed and nitrogen concentration increased, the $O_2$ uptake rate and $CO_2$ evolution rate increased. The OUR and CER were 37.3mmol $O_2/\;l$ hr and 20.2 mmol $CO_2/\;L$ hr at peptone 11g / l and agitation speed 990RPM, respectively. In fed batch fermentation, the final concentration of Xanthan gum was enhanced up to 29g / l.

• 한국의류학회지
• /
• 제27권2호
• /
• pp.200-208
• /
• 2003

The purpose of this study is to propose scientific data and to develop complex\ulcornermultifunctional fibers by applying microcapsules containing rosewood oil on wool fabric. Polyurea was used as wall material of microcapsules. The parameters for adoptable condition are 20min of agitation time, 5000rpm of agitation speed, 4% of emulsifier concentration according to the observation with SEM and particle analyzer. The melting peak of microcapsules was shown to be 280$^{\circ}C$ The amount of released rosewood from microcapsules at 25$^{\circ}C$ was below 1 % and at 40% was below 3%. Therefore, polyurea microcapsules is capable of preserving rosewood oil for long self-life at normal temperature. Antimicrobial activity to dry cleaning and ironing cycle of wool fabric treated with microcapsules were maintained.