• Journal of environmental and Sanitary engineering
• /
• v.13 no.1
• /
• pp.32-43
• /
• 1998

혐기성대상과정중 메탄생성균(methanogenic bacteria)에 의한 메탄생성시 주요 기질인 아세트산 (acetic acid)을 분해할 경우에 여러 가지 복합기질 중 아미노산 첨가에 의한 분해속도증가에 미치는 영향과 투입한 아미노산이 미생물에 의하여 생체량으로 합성되는 정도를 고찰하였다. 실험결과 메탄생성균은 glycine, serine, threonine, aspartic acid, trytophan 등의 혐기성미생물의 생체량합성에 필요한 물질을 투입할 경우에 아세트산의 분해속도가 증가하였으며, 여러 가지 아미노산을 혼합하여 주입한 결과 분해속도가 17% 향상되었다. 한편, 메탄생성균의 lysing에 의하여 생성된 유기물은 메탄이나 이산화탄소의 최종산물로 전환되기보다는 새로운 메탄생성균의 생체량을 형성하는데 직접 이용되었으며, 아세트산의 분해속도를 52% 증가시켰다. 단순기질(sole substrate)과 복합기질(complex substrate)의 분해는 미생물의 생체량합성에 필요한 여러 가지 중간대사산물간의 상호자극효과에 의하여 복합기질이 용이한 것으로 나타났으며, 유입기질내 활성이 강한 슬러지의 농도는 혐기성처리에 매우 중요한 부분을 차지하였다.

• Microbiology and Biotechnology Letters
• /
• v.26 no.4
• /
• pp.352-357
• /
• 1998

Biodegradation of benzoate and m-toluate was investigated using a Pseudomonas sp. isolated in a continuous culture for 45 days with a step-wise increase of the subsrates. The optimum mixture ratio of benzoate and m-toluate was 75% and 25%, respectively. During 45-day culture, removal of benzoate and m-toluate, which was replaced 2,000 ppm on the 30th day were 94% and 79%, respectively, when COD removal rate was 80%. The enzymatic activity of catechol 1,2-dioxygenase increased and that of catechol 2,3-dioxygenase decreased as the concentration of m-toluate was increased. These results suggested that m-toluate induced enzyme activity for degradation of benzoate. The shape of isolated strain in the continuous culture was investigated with SEM and the results showed that the cell shape was more damage according to the higher concentration of aromatic hydrocarbons. Therefore, we suggested that the tolerance against aromatic hydrocarbons was related to not only enzymatic activity but also characteristic of cell membrane or cell wall.

• Microbiology and Biotechnology Letters
• /
• v.20 no.4
• /
• pp.477-482
• /
• 1992

A bacterial strain Acinetobacter calcoaceticus was examined for its ability to degrade fats, oils and hydrocarbons, and tested for the possibility of application in wastewater treatment. All fats and oils tested were degraded by the strain. About 60% of hexadecane, 26% of fish oiL and 40-54% of vegetable oils were consumed respectively in shaking-flask culture. Saturated fatty acid compositions were about 55% in fish oil and 6-12% in vegetable oils. Increases in cell mass were accompanied with decreases in the concentrations of carbon sources. When jar fermentor in place of shaking-flask was used as a culturing vessel. above 80% of all carbon sources was consumed and yield of cell mass was improved to nearly 1.00. Synthetic wastewaters containing 3% of fat, oil, or hydrocarbon as a sale ca,bon source were treated sequentially with A. calcoaceticus first and then exposed to activated sludge. The concentrations of carbon sources were decreased below 0.06% through the process, and the concentrations of suspended solids were lower than 53 mglml. The data imply the potential use of A. calcoaceticus in wastewater treatment.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.26 no.2
• /
• pp.120-132
• /
• 1993

A continuous hollow fiber membrane reactor(CHFMR) was developed and optimized for the production of yellowfin sole(Limanda aspera) skin gelatin hydrolysates using trypsin. The results were summerized as follows: The $K_m$ value of the CHFMR was 2.4 times higher than that of the batch reactor, indicating reduced enzyme affinity for the substrate. The $K_2$ value of the CHFMR was 8.5 times lower than that of the batch process, showing a significant reduction in trypsin activity in the CHFMR. The optimum operating conditions for the CHFMR process were $55^{\circ}C$, pH 9.0, flux 7.79 ml/min, residence time 77min, and trypsin to substrate ratio, 0.01(w/w) After operating for 60min under the above conditions, $79\%$ of the total amount of initial gelatin was hydrolysed. Enzyme leakage was observed through the 10,000 MWCO membrane after the 20min of reactor operation, while none occurred after 5hr. Total enzyme leakage was about $12.95\%$ at $55^{\circ}C$ for 5hrs. However, there was no apparent correlation between enzyme leakage and substrate hydrolysis. The membrane has a significant effect on trypsin activity loss for 60min of the CHFMR operation. The CHFMR operating with the membrane lost $34\%$ of the initial activity versus a $23\%$ loss of activity after 3hr in the continuous reactor lacking the hollow fiber membrane. The measurement of fouling property showed that relative flux reduction was $91\%$ and flux recover rate was $92\%$ at $10\%$ substrate solution. The productivity(378.85mg product/mg enzyme) of the CHFMR was more than 4 times higher than that of the batch reactor at $55^{\circ}C$.

• KSBB Journal
• /
• v.22 no.1
• /
• pp.43-47
• /
• 2007

The effect of surfactant on the hydrolysis of used newspaper was investigated. The most suitable surfactant for the pretreatment stage was found to be NP-series surfactants among 9 kinds of non ionic surfactants. Process parameters such as surfactant concentration, mixing speed, pretreatment temperature and time were tested to optimize for maximum digestibility and 0.5%, 100rpm, 30$^{\circ}C$, and 1 h were found to be optimum, respectively. In order to maximize digestibility, substrate was pretreated with NP-20 and then the pretreated substrate was hydrolyzed by adding TW-80. The effect of surfactant on the hydrolysis of previously surfactant-pretreated newspaper was marginal. Therefore, the digestibility with the addition order of enzyme and surfactant was investigated by using surfactant only in hydrolysis stage. The results show that digestibility was more lowered as the surfactant addition after adding enzyme to substrate was more delayed.

• Membrane Journal
• /
• v.12 no.1
• /
• pp.21-27
• /
• 2002

The formation of soluble microbial products(SMP) and molecular weight distribution on loading rate were observed in batch-type culture medium, which phenol was fed as a substrate. The molecular weight destribution was obtained by using 30K, 100K dalton and $0.45{\mu}$ membrane filters. When the phenol concentrationas a substrate was 120, 230 and 440 mg/L , the specific substrate utilization rate(q) showed 0.639, 1.281 and 1.744 mgTOC/mgMLSS/day, respectively. The endogenous biomass decay rate constant($K_d$) at each substrate concentration was 0.00536, 0.0661 and 0.0749($day^1$), respectively. The $SMP_e$ product rate constant($k_{SMP}_ e$) showed 0.006, 0.0058 and 0.0057($day^1$), respectively. The initial influent substrate during the course of time degraded and produced $SMP_s$. The $SMP_s$ was converted to the $SMP_{nd}$ and endogenous phase converted to the $SMP_e$ ingredients. The molecula weight distribution on loading rate was converted to a higher MW during the course of time.

• Proceedings of the Korean Society for Applied Microbiology Conference
• /
• 1986.12a
• /
• pp.508-508
• /
• 1986

이온성 계면활성제 존재하에서 유기용매에 물을 첨가하면 물이 계면활성제에 약해 둘러싸이면서 유기용매에 용해되어 의사 이상계가 형성된다. 이러한 계를 역미셀 또는 W/O microemulsion이라고 하며 계면활성제로 둘러 쌓인 물분자 집하체를 water pool이라고 한다. 그런데, 10여년 전 water pool에 bipolymer를 용해시킬 수 있다는 사실이 밟혀짐에 따라 이러한 체계를 생체막을 단순화시킨 모형막으로서 막을 통해 일어나는 여러 가지 현상의 규명에 이용하거나 물에 불용성인 기질의 효소 촉매반응의 반응계로 이용하는 연구가 꾸준히 이루어져 있다. 본 강연은 역미셀계에 리파제를 용해시켜 유지의 가수분해를 유도함으로써 지방산을 생산하는 방법에 관한 연구이다. 역미셀계에서 리파제의 특성은 에멀전계와 비교했을 때 큰 차이가 없었으며 물과 계면활성제의 몰 비율(R값)은 효소의 초기반응 속도에 커다란 영향을 끼치는 인자로 나타났다. 올리브유 농도가 5%(v/v), AOT농도가 0.1M, 초기 물 농도가 1.0M의 조건에서 유지의 회분식 가수분해 실험을 행한 결과 이 기질은 거의 완전히 가수분해되었으며, 이 반응계에서 R값과 초기 물 농도는 반응의 평형에 커다란 영향을 끼치는 것으로 나타났는데 초기 물 농도가 증가할수록 평형 가수분해율은 증가하였단 이러한 결과를 반응속도론 측면에서 분석한 결과 역미셀계에서 리파제 반응은 에멀전계에서와는 달리 2차 반응을 따르는 것으로 나타났다. 물 농도가 평형 가수 분해율과 속도 변수에 끼치는 영향을 수학적으로 표시하기 위하여 2차 가역적 반응 속도론에 근거하여 가수분해율, 평형상수, 속도상수 둥을 나타내는 식을 유도하였고 이를 바탕으로 여러 가지 실험 조건 하에서 리파제 반응의 반응 시간에 따른 가수분해율을 예측한 결과는 실제 실험 결과와 잘 일치하였다(편차는 5%). 또한 속도상수와 R값과의 관계식 및 유도한 방정식을 이용하여 추정한 초기속도와 평형 가수분해율을 최대화하는 R값은 각각 10.4 와 11.4 였다.

• Journal of Korean Society of Environmental Engineers
• /
• v.30 no.11
• /
• pp.1161-1169
• /
• 2008

The removals of TCE and PCE vapor with or without a supply of toluene as a primary substrate were compared in a biofiltration process, and the variations of microbial communities associated with the removal were also investigated. As a result of investigations on the removals of TCE/PCE in a biofilter B within which TCE/PCE-acclimated sludge was attached on the surface of media without a supply of primary substrate, and those in another biofilter A where toluene-acclimated sludge was attached with a supply of toluene as a primary substrate, followings were found: (i) parts of microbes responsible to the decomposition of toluene vapor participate in the removal of chlorinated VOCs such as TCE and PCE, and (ii) effective biological removals of TCE and PCE vapor do not necessarily need cometabolism. Sequencing of 16S rDNA obtained from the band profile of DGGE (Denaturating Gradient Gel Electrophoresis), it was confirmed that: (i) uncultured alpha proteobacterium, uncultured Desulfitobacterium, uncultured Rhodobacteraceae bacterium, Cupriavidus necator, and Pseudomonas putida were found to be toluene-decomposing microbes, (ii) alpha proteobacterium HTCC396 is a TCE-removing microbe, (iii) Desulfitobacterium sp. is a PCE-decomposing microbe, and (iv) particularly, uncultured Desulfitobacterium sp. is probably a microbe decomposable not only toluene but also various chlorinated VOC vapor including TCE and PCE.

• Journal of the Korean Wood Science and Technology
• /
• v.29 no.4
• /
• pp.67-78
• /
• 2001

Two species(Quercus mongolica, populus euramericana) of hardwood chips were subjected to steam explosion 25 kg/$cm^2$, for 6 min. The exploded woods were treated by the single or multi-stage chemical process with sodium hydroxide, sodium hypochlorite and sodium chlorite. The multi-stage treatment of exploded wood can be successfully removed lignin. Enzymatic hydrolysis rate of substrate varied from 25% for exploded wood to about 80% for the multi-chemical treated exploded wood. The enzymatic susceptibility was different among wood species. The multi chemical treatment of the exploded wood resulted in the high rate of glucose in the enzymatic hydrolyzate. Cellulase adsorption increased at high lignin content of substrates, while crystallinity, pore area and specific surface area of substrates did not affected enzyme adsorption. According to the proposed pretreatment and saccharification process in this study, it can be acquired about 37~40 kg of glucose from 100 kg of hardwood.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
• /
• 2001.09a
• /
• pp.235-238
• /
• 2001

Monod kinetics에 관련된 주요 생분해 파라미터를 도출하기 위하여 microcosm 규모의 배치실험에서 BTEX 화합물에 대해 분해능이 우수한 Pseudomonas aeruginosa을 이용해 다양한 농도의 벤젠에 대한 분해기작을 고찰하였다. 벤젠의 생분해율(D)과 Maximumspecific growth rate ($\mu$$_{max}$)는 기질의 농도가 증가할수록 높아지다가 최고점에 도달 후에 점차적으로 감소하였으며 이것은 어느 한계점 이상의 벤젠 농도가 미생물의 생분해에 방해 요소로 작용한다는 것을 나타낸다. 그러나 미생물에 의한 벤젠 분해의 상관관계를 나타내는 yield coefficient(Y)는 벤젠의 초기 농도가 낮을수록 높은 값을 나타내었다. Microbial decay constant( b)와 half-saturation constant(K$_{c}$)는 각각 0.21~0.48day$^{-1}$와 218mg/$\ell$로서 문헌값 보다 높은 수치를 나타내었다. 실험으로부터 결정된 생분해 파라미터들은 초기 벤젠 농도에 따라 큰 차이를 보이므로 생분해 모델링에 사용할 파라미터는 기질농도에 따라 적절하게 선택되어야 한다고 사료된다.