• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 1988년도 한국자동제어학술회의논문집(국내학술편); 한국전력공사연수원, 서울; 21-22 Oct. 1988
• /
• pp.476-481
• /
• 1988

In this paper a pH process of a weak acid with a strong base is modeled into a bilinear form, and a self-tuning pH control algorithm which is robust against initial values of solution and disturbances is presented. The control algorithm employs the recursive least square method for the parameter estimation and the generalised minimum variance criterion as the objective function. The computer simulation shows that the tracking of desired pH values is obtained in satisfactory manner regardless of the initial values chosen for the process.

• 한국생물공학회:학술대회논문집
• /
• 한국생물공학회 2000년도 추계학술발표대회 및 bio-venture fair
• /
• pp.325-328
• /
• 2000

The effects of DO and pH on the mass production of pullulan with high-molecular weight from A. pullulans ATCC 42023 were evaluated. The maximum pullulan production yield (51%) was obtained at pH non control (initial pH 6.5) and DO control (above 50%) condition. The pullulan degrading enzyme was activated when the pH of broth reached lower than 5.0 and portion of low molecular weight pullulan was increased. The formation of a black pigment was observed at the initial stationary phase, 40hr of fermentation. Therefore, the fermentation should be carried out in pH non control and DO control condition and harvested before reaching stationary phase around 40h for the production of high molecular weight pullulan.

• Journal of Microbiology and Biotechnology
• /
• 제12권1호
• /
• pp.1-7
• /
• 2002

The effects of DO and pH on the mass production of pullulan with high molecular weight and the morphology of A. pullulans ATCC 42023 were evaluated. A. pullulans showed a maximum production of pullulan (11.98 g/l) when the initial pH of the culture broth was 6.5 in a shake-flask culture. In a batch culture, the mixture of a yeast-like and mycelial cell forms was found at a pH of 4.5, and the maximum production of pullulan (13.31 g/l) was obtained. However, a high proportion of high molecular weight pullulan (M.W.>2,000,000) was produced at a pH of 6.5, with a yeast-like morphology. The maximum pullulan production yield ($51\%$) was obtained at a pH noncontrol (initial pH 6.5) and DO control (above $50\%$) condition. Pullulan degrading enzyme was activated when the pH of the broth was lower than 5.0 and the portion of low molecular weight pullulan was increased. The formation of a black pigment was observed at an initial stationary phase, at 40 h of fermentation. Therefore, the fermentation should be carried out in a pH noncontrol (initial pH of 6.5) and DO control (above $50\%$) condition, and should be harvested before reaching the stationary phase (around 40 h) for the production of high molecular weight pullulan.

• KSBB Journal
• /
• 제15권5호
• /
• pp.444-451
• /
• 2000

Nonliving methanotrophic biomass was used as biosorbent to remove lead which is one of representative pollutants in metal-bearing wastewater. Solution pH, maximum uptake, biosorbent dose and ionic strength were considered as major factors for adsorption experiments. The optimum pH range for lead removal was increased 3.8∼11.0 for methanotrophic biomass compared to biosorbent-free control, pH of 8.4∼11.2. Removal efficiency of lead by methanotrophic biomass was pH dependent, but less sensitive than that of control. In isotherm experiments with 0.2g biosorbent/L at initial solution pH 5.0, methanotrophic biomass took up lead from aqueous solutions to the extent of 1085 mg/g biomass. Removal amount of lead increased with an increase of biomass dose. According to biomass dose for initial 1000 mg Pb/L at initial pH 5.0, the optimum amount of biomass for maximum lead removal per unit methanotrophic biomass was 0.2 g biomass/L. As a result of scanning electron microscope (SEM) micrographs equipped with energy dispersive spectroscopy (EDS), lead removal by methanotrophic biomass seemed to be through adsorptions on the surface of methanotrophic biomass and exopolymers around the biomass. EDS spectra confirmed that lead adsorption appeared on the biomass and exopolymers that may be effective to lead removal comparing before and after contact with lead. Removal efficiency of lead was slightly affected by ionic strength up to 2.0 M of NaCl and NaNO$_3$respectively.

• Journal of Animal Science and Technology
• /
• 제47권4호
• /
• pp.615-624
• /
• 2005

본 연구는 배양초기 pH 조건이 F. succino- genes의 섬유소 부착과 섬유소 소화에 미치는 영향을 보고자 실시하였다. 선정된 specific primer를 이용하여 F. succinogenes의 genomic DNA로부터 445bp의 16S rDNA 절편을 증폭하여 205bp의 internal control을 제작하였고, cPCR 결과로부터 박테리아 수를 계산할 수 있는 표준곡선의 회귀식($r^2$>0.99)을 얻을 수 있었다. In vitro 배양초기 pH에 따른 F. succ- inogenes의 cellulose 부착을 cPCR로 모니터링한 결과, 발효과정 전 기간동안 초기 pH가 6.8과 6.2일 때 cellulose 건물 g당 부착 균주의 수가 pH 5.6일 때 보다 높았으나, pH 6.8과 6.2 사이에서는 큰 차이는 없었다(p>0.05). Cellulose 분해는 배양시간이 진행됨에 따라 증가 되었으며, 분해 정도는 pH가 증가함에 따라 더 높았다. 배양초기 pH가 6.8, 6.2 그리고 5.8일 때 48시간동안 감소한 pH는 각각 0.24, 0.58 그리고 0.16 이었다. 가스 생산량은 발효 시간이 경과함에 따라 pH가 높을수록 더 많았다. 결론적으로 발효 초기 pH는 F. succinogenes에 의한 cellulose 소화, 가스 생산, pH 변화 및 cellulose 부착에 큰 영향을 주었으며, 특히, 낮은 pH(5.8)에서는 섬유소 소화 및 박테리아 부착을 현저한 감소 시켰다.

• 한국식품과학회지
• /
• 제33권5호
• /
• pp.545-550
• /
• 2001

Effects of high hydrostatic pressure on pH, titratable acidity, color, hardness and microorganisms of Chinese Cabbage Kimchi were investigated. Kimchi was pressurized at $200{\sim}600$ MPa for 5 min. There were no significant differences in color and hardness between control and pressurized Kimchi (p>0.05). Total aerobes and lactic acid bacteria were effectively inactivated by high hydrostatic pressure above 400 MPa. Changes in pH, titratable acidity, color, hardness and microbial counts for 4 weeks storage of Kimchi were investigated Kimchi was pressurized at 400 MPa for 5 min and stored at $4^{\circ}C$. The pH of control decreased to 3.94 but pressurized Kimchi maintained its initial pH value throughout the storage. The color of control showed significantly low values compared with pressureized Kimchi (p<0.05), but hardness was not significantly changed (p>0.05). Total aerobes and lactic acid bacteria in the control were reduced from the initial value of $10^8{\sim}10^9$ CFU/mL to $10^6$CFU/mL after 4 weeks storage. Whereas microbial counts in pressurized Kimchi was maintained about $10^3{\sim}10^4$ CFU/mL during storage.

• 대한환경공학회지
• /
• 제22권12호
• /
• pp.2163-2173
• /
• 2000

메탄자화균에 의한 코발트 제거의 최적 pH 영역은 6.0~12.0이었으나 메탄자화균을 넣지 않은 blank는 10.5~11.5이었다. 코발트의 제거능은 pH에 크게 의존하였으나 blank보다는 민감하지 않았다. 초기 pH 6.0에서 1.0 g/L의 메탄자화균을 투입했을 때 170 mg Co/g biomass가 제거되었다. SEM 분석 결과에 의하면 코발트는 메탄자확균의 표면이나 세포의 분비 고분자에 흡착되어 제거된 것으로 사료된다. 초기 pH 6.0, 400 mg Co/L에서 메탄자화균의 최적의 투입량은 1.0 g/L이었다. 2.0 M NaCl과 $NaNO_3$의 높은 이온강도 하에서도 코발트 제거능은 그다지 영향을 받지 않았다.

• 한국환경과학회지
• /
• 제30권2호
• /
• pp.161-172
• /
• 2021

This study was initiated to isolate the microorganisms removing phosphorus (P) from domestic sewage and to investigate the effects of environmental factors on the growth and P removal of the isolated bacteria. Microorganisms isolated from the sewage were identified as Chryseobacterium sp., Stenotrophomonas maltophilia, and Bacillus licheniformis. Among them, Bacillus licheniformis was selected as the P removal microorganism. The environmental factors considered in this study included initial phosphorus concentration, temperature, pH, and carbon source. At initial P concentrations of 10, 20, and 30 mg/L, the P removal efficiencies were 100.0%, 84.0%, and 16.5%, respectively. At 20℃, 30℃, and 40℃, the P removal efficiencies were 0%, 75.8%, and 60.6%, respectively. The removal efficiencies of phosphorus according to pH were 1.6%, 91.7%, and 51.1% at pH 5, pH 7, and pH 9, respectively. Using glucose, acetate, and glucose + acetate as carbon sources yielded P removal efficiencies of 80.9%, 33.6%, and 54.1%, respectively. Therefore, the results from the study demonstrated that the P removal efficiencies of Bacillus licheniformis were the highest when the initial P concentration, temperature, pH, and carbon source were 10 mg/L, 30℃, 7, and glucose, respectively.

• 한국미생물·생명공학회지
• /
• 제26권2호
• /
• pp.96-101
• /
• 1998

여러 가지 외부 탄소원(acetic acid, glucose, methanol, molasses)으로 활성 슬러지를 이용하여 탈질 효과를 살펴보았다. 질산성 질소와 아질산성 질소를 질소원으로 하는 혐기성 슬러지의 회분식 배양을 통해 탈질속도, COD 소비, 탈질율을 조사해 본 결과 molasses는 탈질속도나 COD 소비에서 glucose와 비슷하고 acetic acid나 methanol보다 높았으나, 탈질 효율에 있어서는 질산성 질소나 아질산성 질소배지에서 30-40%가 암모니아로 축적되어 탈질 효율이 떨어졌다. 이러한 현상은 molasses와 glucose를 탄소원으로 이용한 경우 발효에 의해 pH저하를 초래하고 이로 인해 탈질 효율이 감소되는 것으로 생각된다. 따라서 초기 pH를 조절하고 외부 탄소원은 molasses를 이용, 탈질 효과를 조사한 결과 pH 8일 때 암모니아의 축적은 거의 없었으며 탈질 속도에 있어서도 acetic acid의 경우보다 12시간정도 빠른 24시간 안에 99% 이상 탈질 효율이 증가함을 알 수 있었다.

• 한국미생물·생명공학회지
• /
• 제22권5호
• /
• pp.522-530
• /
• 1994

Bacteriocin-producing lactic acid bacteria, Lactococcus sp. HY 449, was isolated from dairy products. Using response surface methodology, the various concentrations of medium compo- nents (tryptone, glucose, yeast extract, tween 80, and initial pH) were tested to find the optimum conditions for maximum bacteriocin production and growth of Lactococcus sp. HY 449. Central composite design was used to control the concentrations of medium components in the experiment. Bacteriocin production and cell growth of Lactococcus sp. HY 449 were most affected by glucose and yeast extract. Estimated optimum growth conditions of Lactococcus sp. HY 449 were as follows; tryptone 1.08%, glucose 1.129%, yeast extract 0.674%, tween 80 0.11%, and initial pH 7.19. Also estimated optimum conditions for bacteriocin production were tryptone 0.937%, glucose 1.108%, yeast extract 0.163%, tween 80 0.09%, and initial pH 6.98.