• Title/Summary/Keyword: Dissolved oxygen (DO)

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Effects of Dissolved Oxygen on Fungal Morphology and Process Rheology During Fed-Batch Processing of Ganoderma lucidum

  • Fazenda, Mariana L.;Harvey, Linda M.;McNeil, Brian
    • Journal of Microbiology and Biotechnology
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    • v.20 no.4
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    • pp.844-851
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    • 2010
  • Controlling the dissolved oxygen (DO) in the fed-batch culture of the medicinal mushroom Ganoderma lucidum led to a 2-fold increase of the maximum biomass productivity compared with uncontrolled DO conditions. By contrast, extracellular polysaccharide (EPS) production was two times higher under oxygen limitation (uncontrolled DO) than under increased oxygen availability (controlled DO). Morphologically, dispersed mycelium was predominant under controlled DO conditions, with highly branched hyphae, consistent with the enhanced culture growth noted under these conditions, whereas in the uncontrolled DO process mycelial clumps were the most common morphology throughout the culture. However, in both cultures, clamp connections were found. This is an exciting new finding, which widens the applicability of this basidiomycete in submerged fermentation. In rheological terms, broths demonstrated shear-thinning behavior with a yield stress under both DO conditions. The flow curves were best described by the Herschel-Bulkley model: flow index down to 0.6 and consistency coefficient up to 0.2 and 0.6 Pa $s^n$ in uncontrolled and controlled cultures DO, respectively. The pseudoplastic behavior was entirely due to the fungal biomass, and not to the presence of EPS (rheological analysis of the filtered broth showed Newtonian behavior). It is clear from this study that dissolved oxygen tension is a critical process parameter that distinctly influences G. lucidum morphology and rheology, affecting the overall performance of the process. This study contributes to an improved understanding of the process physiology of submerged fermentation of G. lucidum.

Quantitative Visualization of Dissolved Oxygen Concentration Field in Micro Flows using PtOEP/PS Membrane (마이크로 유동에서 PtOEP/PS 박막을 이용한 용존 산소 농도장의 정량적 가시화)

  • Song, Dae-Hun;Kim, Hyun-Dong;Kim, Kyung-Chun
    • Journal of the Korean Society of Visualization
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    • v.9 no.1
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    • pp.36-41
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    • 2011
  • It is highly needed to measure the dissolved oxygen (DO) concentration field in water for a variety of purposes such as biological, industrial, environmental monitoring and medical application. Application of PSP (Pressure Sensitive Paint) which is sensitive to oxygen concentration has been carried out to measure DO concentration field using PtOEP/PS film and intensity based method under the UV-LEDs illumination. A micro round water jet having 100% of DO was obliquely impinged on to a PtOEP/PS film coated plate placed in a 0% of DO water container. DO concentration fields on the impinging plate were quantitatively visualized with a $2.94\;{\mu}m$ of spatial resolution. Through pixel-by-pixel calibration, uncertainty of each pixel by different sensitivity, different dye concentration and non-uniformity of illumination was removed. It is demonstrated that the high DO concentration region was coincided with the impingement area. The DO concentration gradient due to DO diffusion was affected by Reynolds number.

Fuzzy algorithm of Automatic control for dissolved oxygen in Activated sludge aeration tank (활성슬러지 폐수처리장 폭기조 DO제어를 위한 퍼지 제어 알고리즘 연구)

  • 손건태;김성덕;고주형
    • Journal of Environmental Science International
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    • v.8 no.4
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    • pp.533-538
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    • 1999
  • Fuzzy algorithm of automatic control for dissolved oxygen(DO) concentration in the aeration tank of an activated sludge process is proposed. Among variables repirometry and air flowrate are selected as significant input factors and the relationship with DO is estimated using a multiple regression model. The DO concentration and the amount of repirometry are fuzzified and the fuzzy rule base are determined. Using the fuzzy algorithm, the change of amount of air flowrate are determined and the change of amount of DO is derived.

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Effect of Salinity on Dissolved Oxygen Characteristics in an Ejector-Aerator (이젝터-폭기 시스템의 용존산소특성에 미치는 염도의 영향)

  • Yang, Hei-Cheon;Park, Sang-Kyoo
    • Journal of Advanced Marine Engineering and Technology
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    • v.35 no.5
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    • pp.640-646
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    • 2011
  • Dissolved oxygen (DO) refers to the volume of oxygen that is contained in water, and is a major indicator of water quality. The objective of this paper was to investigate the effect of salinity on the dissolved oxygen characteristics in an ejector-aerator. An experimental aeration system composed of a motor-pump, an ejector, a motor-blower, a set of aeration and recirculation tank and a control panel. The dissolved oxygen concentrations decreased with the water salinity. The volumetric mass transfer coefficient increased with increasing the water salinity.

The Effect of Dissolved Oxygen on Microbial Transglutaminase production by Streptoverticillium morbaraense (용존산소 농도 조절이 미생물유래 Transglutaminase 생산에 미치는 영향)

  • 유재수;전계택;정용섭
    • KSBB Journal
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    • v.18 no.2
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    • pp.155-160
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    • 2003
  • The effect of dissolved oxygen(DO) on microbial transglutaminase(mTG) production by Streptoverticillium morbaraense was studied in on-line computer controlled fermentation system. In order to control dissolved oxygen during fermentation, the agitation speed and aeration rate of 2.5 L fermenter ranged from 260 to 360 rpm and 0.3 to 3.9 L/min, respectively. The maximum microbial transglutaminase production was obtained at controlled 20% of dissolved oxygen among the various dissolved oxygen controlled batch cultures tested. The production of microbial transglutaminase at controlled 20% of dissolved oxygen was about 2.12 U/mL which was 1.1 times higher than that obtained in batch culture without control of dissolved oxygen. Also, the highest microbial transglutaminase production was obtained in fed-batch cultures in which dissolved oxygen was controlled at 20%, and it was improved almost 1.3 times in comparison with that without control of dissolved oxygen. Maximal dry cell weight and microbial transglutaminase production were 13.2 g/L and 2.6 U/mL, respectively. Finally, it was also found that fed-batch fermentation at controlled 20% of dissolved oxygen showed a good performance for the microbial transglutaminase production by on-line computer controlled fermentation system which may be generally applicable to other microbial cultures.

Nitrospira Community Composition in Nitrifying Reactors Operated with Two Different Dissolved Oxygen Levels

  • Park, Hee-Deung;Noguera, Daniel R.
    • Journal of Microbiology and Biotechnology
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    • v.18 no.8
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    • pp.1470-1474
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    • 2008
  • Nitrospira is a dominant member of nitrite-oxidizing bacteria (NOB) in nitrifying bioreactors as well as in natural habitats. In this study, Nitrospira NOB were investigated in the two nitrifying reactors operated with high and low dissolved oxygen (DO) concentrations for a period of 300 days. Phylogenetic and terminal restriction fragment length polymorphism analyses based on 168 rRNA gene sequences revealed that the Nitrospira community compositions of the two reactors during the early period related to group 1 and half of the Nitrospira community composition shifted to group 2 in the high-DO reactor after day 179, although there was no significant change in the low-DO reactor. These results suggested that DO was an important factor affecting Nitrospira community compositions in the nitrifying reactors.

On-line monitoring of microorganism cultivation processes using optical sensing membranes for simultaneous detection of dissolved oxygen and pH (용존산소와 pH의 동시 검출용 광학 센서 막을 이용한 미생물 발효공정의 온라인 모니터링)

  • Kim, Chun-Kwang;Rhee, Jong-II
    • KSBB Journal
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    • v.24 no.1
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    • pp.106-112
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    • 2009
  • An optical sensing membrane has been fabricated to measure the concentration of dissolved oxygen(DO) and pH value simultaneously. It has employed HPTS as a pH sensitive dye and a ruthenium(II) complex as a DO sensitive dye. The sensing membrane has been applied to wells in a 24-well microtiter plate. Using the 24-well microtiter plate the concentrations of dissolved oxygen and pH values have been on-line monitored during the cultivations of E.coli DH5${\alpha}$, B.cereus 318 and P.pastoris X-33. On-line monitoring of DO and pH in microorganism cultivation processes showed good performance of the sensing membrane containing 5 mM HPTS and 2 or 5 mg/mL Rudpp.

Development of low power type sensor for the DO concentration measurement by clark electrode (Clark전극에 의한 DO 농도측정을 위한 절전형 센서개발에 관한 연구)

  • 이동희
    • Electrical & Electronic Materials
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    • v.8 no.3
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    • pp.254-260
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    • 1995
  • A method is described for the design and fabrication of the sensor interface circuits on the Clark electrodes for the dissolved oxygen(DO). The discussion includes a method for the +5 V single-supply driving for the sensor circuits, which has low power comsumption for the front-end electronics. DO probe under test is composed of the Clark electrode with silver anode, gold cathode and the electrolyte of half saturated KCI solution and the FEP teflon memtrance for the oxygen penetration. Typical polarograms for the DO probes by using this sensor circuit reveals high accuracy over 99% of the I to V conversion. Partial pressure of oxygen obtained from the polarograms are well suited to the results calculated. It is expected that the proposed sensor circuits can be utilized into the customized IC for the battery-driven small-size DO meters.

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Characterization of Pseudomonas aeruginosa Growth under High Dissolved Oxygen Concentration : Selection of the High Dissolved Oxygen Resistant Mutant pseudomonas aeruginosa M-10 (고용존산소 농도에서의 산소내성 Pseudomonas aeruginosa 돌연변이주 M-10 생장거동)

  • Lee, Hang-Woo
    • Korean Journal of Microbiology
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    • v.35 no.4
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    • pp.283-288
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    • 1999
  • The effect of dissolved oxygen(DO) concentration on the growth of Pseudomonas aeruginosa and it's mutant M-10 was studied the growth kinetics and the possibility of waste treatment for reducing the amount of excess sludge. Different DO concentrations on the growth of wild type Pseudomonas aeruginosa affected to cellular yields, decreasing with increasing DO concentrations. Under these conditions, the maximum 14 folds decrease of cellular yield was achieved at 90 ppm DO levels by screened, being able to reduce their cellular yields under low DO concentration. The optimum mutation conditions were obtained by the treatment of NTG mutagen at 30${\circ}C$ for 1 hr. The growth characteristics of the selected mutant M-10 showed the same as the wild type growth kinetics. However, cellular yields are significantly decreased to 55% compared with those of wild type under DO concentrations increased. We, therefore, expect the application of the mutants to waste treatment for reducing excess sludge.

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Prediction of DO Concentration in Nakdong River Estuary through Case Study Based on Long Short Term Memory Model (Long Short Term Memory 모델 기반 Case Study를 통한 낙동강 하구역의 용존산소농도 예측)

  • Park, Seongsik;Kim, Kyunghoi
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.33 no.6
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    • pp.238-245
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    • 2021
  • In this study, we carried out case study to predict dissolved oxygen (DO) concentration of Nakdong river estuary with LSTM model. we aimed to figure out a optimal model condition and appropriate predictor for prediction in dissolved oxygen concentration with model parameter and predictor as cases. Model parameter case study results showed that Epoch = 300 and Sequence length = 1 showed higher accuracy than other conditions. In predictor case study, it was highest accuracy where DO and Temperature were used as a predictor, it was caused by high correlation between DO concentration and Temperature. From above results, we figured out an appropriate model condition and predictor for prediction in DO concentration of Nakdong river estuary.