• Title/Summary/Keyword: AI/ML

검색결과 149건 처리시간 0.026초

해상운임의 구조변화 리스크 추정 (Risk Estimates of Structural Changes in Freight Rates)

  • 김현석
    • 한국항만경제학회지
    • /
    • 제39권4호
    • /
    • pp.255-268
    • /
    • 2023
  • 본 연구는 기존의 비선형 추정에 기초한 구조 단절/변화를 검정하기 위한 모형을 선형 회귀 분석으로 일반화한 모형으로 효율적 추정이 가능함을 제시하고자 한다. 특히, 효율적인 추정을 위해 인공지능, 머신러닝 등 분야와 관련해 구조 단절/변화 모니터링에 대한 관심이 높아지는 최근 이슈에 대해 선형회귀에 근거한 본 연구의 실증분석 결과는 구조 단절을 명확하게 추정하였으며, 글로벌 시황을 나타내는 대표적인 건화물선 운임 지수(발틱 드라이 벌크 지수, BDI)에 대한 적용 결과는 기존 연구와 일치하는 추정 결과를 제시한다. 이상의 선형 회귀에 근거한 분석은 CUSUM, MOSUM, F-통계 기반 프로세스 등 경험적 변동 프로세스의 피팅, 시각화 및 평가를 위한 다양한 유형의 추정에서 통계적으로 유의한 것으로 나타났다. 추가적으로 기존 연구에서 제시한 PELT(pruned exact linear time)를 적용한 추정에서도 유사한 추정 결과를 각각 나타낸다.

계작지모가우슬탕(桂芍知母加牛膝湯) 약침이 류마티스 관절염 생쥐에 미치는 영향 (A Study on the Effect and Mechanism of Gamikyejakjimogawusul-tang Herbal Acupuncture on Induced Rheumatoid Arthritis model of DBA/1 mice)

  • 정순현;조종관;김소연;김영일
    • 혜화의학회지
    • /
    • 제24권2호
    • /
    • pp.35-57
    • /
    • 2016
  • Objectives : The purpose of this study is to prove the effect and mechanism of Gamikyejakjimogawusul-tang(GKHA) herbal acupuncture on induced rheumatoid arthritis model of DBA/1 mice. Methods : We check effect of GKHA extract on the AST, ALT, Creatinine, BUN of serum and cell viability of GK extract in RAW 264.7 cells to test the stability of this study. In vitro, we measure total phenol contents, total flavonoid contents, DPPH free radical scavenging activity, ABTS cation radical scavenging activity of Gamikyejakjimogawusul-tang, effect of GK extract on ROS(Reactive Ooxygen Species) production to estimate a anti-oxidant capacity, and we also measure effect of GK extract on NO (Nitric Oxid), IL-$1{\beta}$, IL-6, IL-17, IL-21, TNF-${\alpha}$, MCP-1, GM-CSF production in RAW 264.7 cells to estimate a anti-inflammatory efficacy. In vivo, we compare a rheumatoid arthritis manifestation between control and experimental group and estimate a AI. Then we check effect of GKHA on the level of WBC, neutrophil, lympocyte, monocyte in the blood to see the effect of immune cells in blood. In addition we measure effect of GKHA on the level of hs-CRP, IgM, IgG, IL-$1{\beta}$, IL-6, IL-17, IL-21, TNF-${\alpha}$, MCP-1, GM-CSF in serum. We observe effects of GKHA on imaging of cartilage degeneration using micro CT-arthrography in paw hind. And we calculate effects of GKHA that reduced BV ratio, BS/BV ratio using 3D Micro-CT. Lastly we observe effects of GKHA histopathologic examination analysis. Results : 1. The toxicity on liver and kidney was disregardable and the cytotoxicity against RAW 264.7 cells was also disregardable. 1. Total phenol contents and total flavonoid contents in GK extract were in high level. 2. DPPH free radical scavenging activity and ABTS cation radical scavenging activity were increased according to concentration of GK extract 3. ROS production was significantly decreased in GK extract (at 10, $100{\mu}g/ml$). 4. NO, IL-6, TNF-${\alpha}$, MCP-1 production were significantly decreased in GK extract(at 10, $100{\mu}g/ml$). IL-17, GM-CSF production were significantly decreased in GK extract(at 1, 10, $100{\mu}g/ml$). IL-$1{\beta}$, IL-21 production were also decreased but there was no statistical significance. 5. 25x observation after H&E and M-T staining, infiltration of immune cells and subsidence of the cartilage and damage to the synovial cells were decreased. Conclusions : This study showed that GKHA extract had anti-oxidant capacity, anti-inflammatory efficacy. GKHA extract also had inhibiting effect on the process of rheumatoid arthritis and can protect joint and cartilage. So we expect that GKHA extract can be a meaningful treatment to rheumatoid arthritis patients.

Potential of fascaplysin and palauolide from Fascaplysinopsis cf reticulata to reduce the risk of bacterial infection in fish farming

  • Mai, Tepoerau;Toullec, Jordan;Wynsberge, Simon Van;Besson, Marc;Soulet, Stephanie;Petek, Sylvain;Aliotti, Emmanuelle;Ekins, Merrick;Hall, Kathryn;Erpenbeck, Dirk;Lecchini, David;Beniddir, Mehdi A.;Saulnier, Denis;Debitus, Cecile
    • Fisheries and Aquatic Sciences
    • /
    • 제22권12호
    • /
    • pp.30.1-30.11
    • /
    • 2019
  • Marine natural products isolated from the sponge Fascaplysinopsis cf reticulata, in French Polynesia, were investigated as an alternative to antibiotics to control pathogens in aquaculture. The overuse of antibiotics in aquaculture is largely considered to be an environmental pollution, because it supports the transfer of antibiotic resistance genes within the aquatic environment. One environmentally friendly alternative to antibiotics is the use of quorum sensing inhibitors (QSIs). Quorum sensing (QS) is a regulatory mechanism in bacteria which control virulence factors through the secretion of autoinducers (AIs), such as acyl-homoserine lactone (AHL) in gram-negative bacteria. Vibrio harveyi QS is controlled through three parallel pathways: HAI-1, AI-2, and CAI-1. Bioassay-guided purification of F. cf reticulata extract was conducted on two bacterial species, i.e., Tenacibaculum maritimum and V. harveyi for antibiotic and QS inhibition bioactivities. Toxicity bioassay of fractions was also evaluated on the freshwater fish Poecilia reticulata and the marine fish Acanthurus triostegus. Cyclohexanic and dichloromethane fractions of F. cf reticulata exhibited QS inhibition on V. harveyi and antibiotic bioactivities on V. harveyi and T. maritimum, respectively. Palauolide (1) and fascaplysin (2) were purified as major molecules from the cyclohexanic and dichloromethane fractions, respectively. Palauolide inhibited QS of V. harveyi through HAI-1 QS pathway at 50 ㎍ ml-1 (26 μM), while fascaplysin affected the bacterial growth of V. harveyi (50 ㎍ ml-1) and T. maritimum (0.25 ㎍). The toxicity of fascaplysin-enriched fraction (FEF) was evaluated and exhibited a toxic effect against fish at 50 ㎍ ml-1. This study demonstrated for the first time the QSI potential of palauolide (1). Future research may assess the toxicity of both the cyclohexanic fraction of the sponge and palauolide (1) on fish, to confirm their potential as alternative to antibiotics in fish farming.

Anti-Proliferation Effects and Molecular Mechanisms of Action of Tetramethypyrazine on Human SGC-7901 Gastric Carcinoma Cells

  • Ji, Ai-Jun;Liu, Sheng-Lin;Ju, Wen-Zheng;Huang, Xin-En
    • Asian Pacific Journal of Cancer Prevention
    • /
    • 제15권8호
    • /
    • pp.3581-3586
    • /
    • 2014
  • Aim: To investigate the effects of tetramethypyrazine (TMP) on proliferation and apoptosis of the human gastric carcinoma cell line 7901 and its possible mechanism of action. Methods: The viability of TMP-treated 7901 cells was measured with a 3-(4, 5-dimethyl-thiazol-2-yl)-2,5-diphenyltetrazolium bromide assay (MTT) and cell apoptosis was analyzed by flow cytometry. The distribution of cells in different phases of cell cycle after exposure of TMPs was analyzed with flow cytometry. To investigate the molecular mechanisms of TMP-mediated apoptosis, the expression of NF-${\kappa}Bp65$, cyclinD1 and p16 in SGC-7901 cells was analyzed by reverse transcription-polymerase chain reaction (RT-PCR) and western blotting. Results: TMP inhibited the proliferation of human gastric carcinoma cell line 7901 in dose and time dependent manners. Cell growth was suppressed by TMP at different concentrations (0.25, 0.5, 1.0, 2.0 mg/ml), the inhibition rate is 0.46%, 4.36%, 14.8%, 76.1% (48h) and 15.5%, 18.5%, 41.2%, 89.8% (72h) respectively. When the concentration of TMPs was 2.0mg/ml, G1-phase arrest in the SGC-7901 cells was significant based on the data for cell cycle distribution. RT-PCR demonstrated that NF-${\kappa}Bp65$ and cyclin D1 mRNA expression was significantly down-regulated in 7901 cells treated with 2.0 mg/ml TMP for 72h (p<0.05), while the p16 mRNA level was up-regulated (p<0.05). The protein expression of NF-${\kappa}Bp65$ and cyclin D1 decreased gradually with the increase in TMP concentration, compared with control cells (p<0.05), while expression of protein p16 was up-regulated (p<0.01). Conclusion: TMP exhibits significant anti-proliferative and pro-apoptotic effects on the human gastric carcinoma cell line SGC-7901. NF-${\kappa}Bp65$, cyclinD1 and p16 may also play important roles in the regulation mechanisms.

초등학교 수학 수업에서의 구체물 활용과 수학적 의사소통에 관한 연구 - 2학년 아동을 중심으로 - (A Study of Using Concrete Materials and Mathematical Communications in the Primary Mathematics Class - Focused on 2nd Grades in Primary school -)

  • 이미애;김수환
    • 한국초등수학교육학회지
    • /
    • 제5권1호
    • /
    • pp.99-120
    • /
    • 2001
  • 본 연구는 초등학교 저학년 아동의 수학적 의사소통 지도의 방향을 모색하고 의사소통에 대한 구체물 활용의 효과에 대하여 새로운 방향을 제시하는데 목적을 두고 수학적 의사소통에는 어떠한 특성이 있으며, 구체물이 수학적 의사소통에 어떠한 영향을 미치는지, 수학 학습에 구체물이 어떠한 영향을 미치는지 알아보고자 하였다. 의사소통 특성으로는 수학적 기호나 용어가 익숙하지 못하고 대체 용어를 사용하고 생활 속의 경험을 학습에 잘 적용시키며, 소수 아동들이 수업을 주도하며, 소집단에서 이루어지는 대화의 방향이 과제 해결 중심으로 이루어지지 못하고 있다. 구체물은 말하기 활동을 촉진시키며, 오류를 쉽게 확인하게 하며 추측과 예상 활동을 수월하게 하고 소집단 활동이 활발히 이루어지게 한다. 반면에 구체물을 활용하면서 교사에게 집중하지 않고 이탈행동을 보임으로써 듣기 활동이 제대로 이루어지지 않고 있다. 학습에 주는 영향으로는 참여도를 높이고, 부진아 학습을 돕고, 개념 형성에 도움을 준다. 또한 과제 해결 능력에 따라 수준별 학습이 쉽게 이루어지도록 한다. 그러나 구체물에 따라 학습에 활용 정도가 다르게 나타났으며 아동들은 절차적 지식보다 개념적 지식을 더 중시하고 있었다. 따라서 구체물은 수학 수업에서 의사소통을 활발하게 이루어지게 도와주며 수학 학습에도 많은 영향을 미치게 되므로 저학년의 수학 수업에서는 구체물의 활용이 꼭 필요하다. 또한 교사는 이러한 아동들의 의사소통의 특성을 고려하여 의사소통 활동이 활발히 이루어질 수 있는 교수 학습 방법을 모색해야할 것이다.된다0.9 mg/ml의 수준에서 측정되었고, 제 11세대에서는 유즙내 인간 hIL-10의 발현 수준을 분석하였을 때, 그 농도는 평균 5.7± 1.5 mg/ml의 수준에서 측정되었고, 제 12세대에서는 유즙내 인간 hIL-10의 발현 수준을 분석하였을 때, 그 농도는 평균 6.3±3.5 mg/ml의 수준으로 측정되었고, 제 13세대에서는 유즙내 인간 hIL-10의 발현 수준을 분석하였을 때, 그 농도는 평균 6.8±4.5 mg/ml의 수준으로 측정되었고, 제 14세대에서는 유즙내 인간 hIL-10의 발현 수준을 분석하였을 때, 그 농도는 평균 6.8±3.1 mg/ml의 수준으로 측정되었다. 이러한 수준은 제 1 세대의 것보다 높은 결과로 형질전환 생쥐에서 인간 IL-10 유전자의 발현은 최소한 15 세대까지 지속적으로 유지된다는 것을 알 수 있었으며, 장기 세대까지도 발현수준이 유지될 것으로 판단된다. 이러한 연구결과는 계통으로 확립된 형질전환 동물에 부여된 새로운 유전형질은 지속적으로 후대로 유전될 수 있음을 제시한다.

  • PDF

Immunotoxicity Following Pre- and Post-natal Aluminum Exposure in Rats

  • Khalaf, Abd EI-Azeim A.;Morgan, Ashraf M.;Mekawy, Mohey M.;Ali, Maged F.
    • Toxicological Research
    • /
    • 제24권1호
    • /
    • pp.51-58
    • /
    • 2008
  • The present study was designed to explore the immunotoxic effects of orally administered aluminum (AI) on pregnant rats (n = 60) and their growing fetuses and consequently on the animal wealth. The animals were randomly allocated into three equal groups of 20 rats each. The first group has no treatment and kept as a control (G1). The second and third groups of pregnant rats were treated orally with aluminum chloride at 345 mg/Kg b.wt. The second group (G2) received the tested compound from the $6^{th}$ day of gestation to the end of weaning, whereas the third group (G3) received the tested compound from the $15^{th}$h day of gestation to the end of weaning. Control and treated animals (dams and offspring) were immunized ip with (0.5 ml) 20% sheep red blood cell (SRBC) suspension seven days before the end of experiments. At the end of exposure, ten dams and ten offspring from each group were used for assessment of cell-mediated immunity and a similar number of animals were sacrificed for evaluating the humoral immune response and serum protein profile. Aluminum chloride exposure of dams ($G_2&G_3$) caused significant suppression of both cell mediated and humoral immune responses in the obtained offsprings compared to the control group ($G_1$) without any significant effect on the immune responses of these dams. Moreover, the serum total globulins, albumin/ globulin (A/G) ratio and gamma globulin fraction were significantly decreased in the treated dam's offsprings compared to the corresponding controls while the serum total protein and all serum protein fractions showed non significant difference between the control and treated dams and between the two treated dam groups themselves. There were no histopathological changes observed in thymus, spleen and liver of the control and treated dams. Thymus of treated dam's offsprings (G2) showed lymphoid depletion in both cortex and medulla. Their spleens showed lymphoid depletion in the white pulps and congestion with hemosiderosis in the red pulps. Liver of treated dam's offsprings showed dilation and congestion of its central vein with degenerative changes in the hepatocytes. These histopathological changes were more severe in G2 than in G3 offsprings. It can be concluded that gestational and/ or lactation exposure of pregnant dams to AI chloride caused suppression of both cellular and humoral immune responses of their offsprings.

외국어로서의 영어 구문 중의성 해결 과정 (Processing of the Syntactic Ambiguity Resolution in English as a Foreign Language)

  • 정유진;이윤형;황유미;남기춘
    • 한국인지과학회:학술대회논문집
    • /
    • 한국인지과학회 2000년도 춘계 학술대회
    • /
    • pp.261-266
    • /
    • 2000
  • 글을 이해하기 위해서는 어휘와 어휘간의 연결 및 전체 구조를 아는 것이 필요하다. 이는 비단 한국어뿐만 아니라 영어나 기타 다른 외국어에서도 마찬가지일 것이다. 본고는 두 가지를 고찰하기 위해 진행되었는데 우선 외국어로서 영어를 처리하는데 발생하는 구문적 중의성을 해결하는데 Garden Path Sentence(GPS), Late Closure(LC), PP의 세 문형에 따라 어떻게 해결하는지 알아보기 위한 것이다. 그리고 각 문형의 중의적 어절에서의 반응과 애매성 해소 어절에서의 반응에 따라 sysntactic module이 작용하는 것인지 알아보고자 한다. 예를 들어 "The boat floated down the streams sank"란 Garden Path 문장이 제시된 경우에 독자는 "sank"란 어휘가 제시되기 전까지 "floated"를 동사로 생각하게 되나 다음에 본동사인 "sank"가 제시될 경우 문장의 해석에 혼란을 갖게 될 것이다. 예문에서 "floated"가 문장에서 어떤 역할을 하는지 결정하는 것은 "sank"를 보고서야 가능하다. 이런 구문적 중의성을 해결하는 방식을 알아보기 위해 어절 단위로 제시된 자극을 읽는 자기 조절 읽기 과제(self-paced reading task)를 사용하였다. 각 어절을 읽는데 걸리는 시간을 측정한 실험 결과 GPS, PP, LC 모두 중의성을 지닌 영역이 중의성을 해소한 후와 각각 유형적으로 큰 차이가 없는 것으로 나타났다. 다만 GPS, CGPS, PP와 CPP는 어절 후반으로 갈수록 반응시간이 짧아졌다. 이는 우리나라 사람의 경우 외국어인 영어의 구문 중의성 해소는 구문 분석 단원(syntactic module)에 의한 자동적 처리라기보다 의미를 고려해 가면서 문법지식을 이용해 추론을 통한 구문 분석이라 할 수 있다.에 의한 자동적 처리라기보다 의미를 고려해 가면서 문법지식을 이용해 추론을 통한 구문 분석이라 할 수 있다.많았다(P<0.05).조군인 Group 1에서보다 높은 수준으로 발현되었다. 하지만 $12.5{\;}\mu\textrm{g}/ml$의 T. denticola sonicated 추출물로 전처리한 Group 3에서는 IL-2와 IL-4의 수준이 유의성있게 억제되어 발현되었다 (p < 0.05). 이러한 결과를 통하여 T. denticola에서 추출된 면역억제 단백질이 Th1과 Th2의 cytokine 분비 기능을 억제하는 것으로 확인 되었으며 이 기전이 감염 근관에서 발견되는 T. denticola의 치수 및 치근단 질환에 대한 병인기전과 관련이 있는 것으로 사료된다.을 보였다. 본 실험 결과, $Depulpin^{\circledR}은{\;}Tempcanal^{\circledR}와{\;}Vitapex^{\circledR}$에 비해 높은 세포 독성을 보여주공 있으나, 좀 더 많은 임상적 검증이 필요할 것으로 사료된다.중요한 역할을 하는 것으로 추론할 수 있다.근관벽을 처리하는 것이 필요하다고 사료된다.크기에 의존하며, 또한 이러한 영향은 $(Ti_{1-x}AI_{x})N$ 피막에 존재하는 AI의 함량이 높고, 초기에 증착된 막의 업자 크기가 작을 수록 클 것으로 여겨진다. 그리고 환경의 의미의 차이에 따라 경관의 미학적 평가가 달라진 것으로 나타났다.corner$적 의도에 의한 경관구성의 일면을 확인할수 있지만 엄밀히 생각하여 보면 이러한 예의 경우도 최락의 총체적인 외형은 마찬가지로 $\ulcorner$순응$\lrcorner$의 범위를 벗어나지 않는다. 그렇기 때문에도 $\ulcorner$순응$\lrcorner$$\ulcorner$표현$\lrcorner$의 성격과 형태를 외형상으로 더욱이 공간상에서는 뚜렷하게 경계

  • PDF

Application of Artificial Intelligence Technology for Dam-Reservoir Operation in Long-Term Solution to Flood and Drought in Upper Mun River Basin

  • Areeya Rittima;JidapaKraisangka;WudhichartSawangphol;YutthanaPhankamolsil;Allan Sriratana Tabucanon;YutthanaTalaluxmana;VarawootVudhivanich
    • 한국수자원학회:학술대회논문집
    • /
    • 한국수자원학회 2023년도 학술발표회
    • /
    • pp.30-30
    • /
    • 2023
  • This study aims to establish the multi-reservoir operation system model in the Upper Mun River Basin which includes 5 main dams namely, Mun Bon (MB), Lamchae (LC), Lam Takhong (LTK), Lam Phraphoeng (LPP), and Lower Lam Chiengkrai (LLCK) Dams. The knowledge and AI technology were applied aiming to develop innovative prototype for SMART dam-reservoir operation in future. Two different sorts of reservoir operation system model namely, Fuzzy Logic (FL) and Constraint Programming (CP) as well as the development of rainfall and reservoir inflow prediction models using Machine Learning (ML) technique were made to help specify the right amount of daily reservoir releases for the Royal Irrigation Department (RID). The model could also provide the essential information particularly for the Office of National Water Resource of Thailand (ONWR) to determine the short-term and long-term water resource management plan and strengthen water security against flood and drought in this region. The simulated results of base case scenario for reservoir operation in the Upper Mun from 2008 to 2021 indicated that in the same circumstances, FL and CP models could specify the new release schemes to increase the reservoir water storages at the beginning of dry season of approximately 125.25 and 142.20 MCM per year. This means that supplying the agricultural water to farmers in dry season could be well managed. In other words, water scarcity problem could substantially be moderated at some extent in case of incapability to control the expansion of cultivated area size properly. Moreover, using AI technology to determine the new reservoir release schemes plays important role in reducing the actual volume of water shortfall in the basin although the drought situation at LTK and LLCK Dams were still existed in some periods of time. Meanwhile, considering the predicted inflow and hydrologic factors downstream of 5 main dams by FL model and minimizing the flood volume by CP model could ensure that flood risk was considerably minimized as a result of new release schemes.

  • PDF

말 정액 동결시 Glycerol 농도와 동결 속도가 생존율에 미치는 영향 (Factors Affecting the Survival Rates of Frozen-Thawed Spermatozoa in Equine by Glycerol Concentration and Freezing Speed)

  • 최선호;김성재;조상래;최창용;손준규;유용희;조영재;최귀철;문윤영
    • Reproductive and Developmental Biology
    • /
    • 제34권3호
    • /
    • pp.271-274
    • /
    • 2010
  • This study was conducted to investigate the survival rate of frozen-thawed spermatozoa in equine by glycerol concentration and freezing speed Two stallions (1 Thoroughbred-13 year old and 1 Arab-7 year old) bred in Korea Racing authority was examined for 1 times in a couple of weeks. Semen was collected by condom method standing heated mare and were centrifuged 650 g for 15 min. and isolated the seminal plasma. Thick fraction of semen was diluted EDTA-Lactose-egg yolk diluents to 1:1 and contained in 0.5 ml straw as $6{\sim}14{\times}10^7\;cells/ml$. Final concentrations of glycerol were 3, 5 and 7% in cryopreseved diluents and added 4 times for 2 hours equilibration. For the freezing, equilibrated straws were located 3 or 5 em above $LN_2$ gas for 5 or 10 min. Survival rates of pre-frozen sperm were $65.0{\pm}13.2%$, $68.3{\pm}10.4%$, $66.7{\pm}11.5%$ and post-frozen were $53.3{\pm}23.1%$, $45.0{\pm}15.0%$, $50.0{\pm}18.0%$ in 3, 5, 7% glycerol concentration, respectively. There was no difference between glycerol concentrations. Survival rates of frozen-thawed sperm on freezing speed were $36.7{\pm}10.4%$, $40.0{\pm}7.1%$, $30.0{\pm}13.2%$ at 3 cm-5 min and $33.3{\pm}11.5%$, $31.7{\pm}2.9%$, $21.7{\pm}10.4%$ at 3 cm-10 min in 3, 5, 7% glycerol concentration, respectively. Survival rates of frozen-thawed sperm on freezing speed were $43.3{\pm}15.3%$, $32.0{\pm}17.9%$, $22.3{\pm}15.7%$ at 5cm-5 min and were $47.5{\pm}15.0%$, $43.3{\pm}12.6%$, $48.3{\pm}15.3%$ at 5cm-10 min in 3, 5, 7% glycerol concentration, respectively. There were significantly different between groups (p<0.05). These results suggest that glycerol concentration did not affect cryopreservation of stallion semen within 3~7% but freezing speed affects. In our experiment, the best cryopreservation condition was at 5 cm above $LN_2$ gas for 10 min for pre-freezing and 7% of glycerol concentration. These results lead to commercial AI with frozen-thawed stallion semen.

유류오염지역에서 분리한 Acinetobacter sp. B2로부터의 Lipase 정제 및 특성 (Purification and Characterization of Lipase from Acinetobacter sp. B2 Isolated from Oil­contaminated Soil)

  • 손성화;박경량
    • 미생물학회지
    • /
    • 제40권4호
    • /
    • pp.320-327
    • /
    • 2004
  • 대전 근교의 유류로 오염된 토양으로부터 유류를 분해하는332개의 세균 콜로니를 분리한 후 이 중 lipase 활성이 우수한 한 균주를 최종 선별하여 생리생화학적 조사와 16S rRNA 염기서열분석 등을 통하여 동정한 결과 Acinetobactor sp. B2로 확인되었다. 최종 선별된 Acinetobactor sp. B2는 trehalose, mannitol을 제외한 다양한 당을 이용하였고, kanamycin, streptomycin, tetracycline, spectinomycin의 항생제에 대해서 약한 내성을, 그리고 Ba, Li, Mn, Al, Cr, Pb 등의 중금속에 대해서는 mg/ml 단위까지 강한 내성을 나타냈고 생장 최적 온도는 $30^{\circ}C$로 확인되었다. Acinetobactor sp. B2에서 정제된 lipase의 분자량은60 kDa이었고, 이 효소의 최적 온도와 PH는 각각 $40^{\circ}C$와 pH 10이었다. 그리고p-nitrophenyl palmitate (pNPP)를 가수분해하는데 필요한 활성에너지는 $4-37{\circ}C$의 범위에서 2.7 kcal/mol 이었고, $60^{\circ}C$ 이상의 온도에서는 불안정한 효소임이 확인되었다. 또 pNPP에 대한 이 효소의 Michaelis constant (Km)와 최대속도상수 $(V_{max})$값은 각각 21.8 ${\mu}M$$270.3\;{\mu}M\;min^{-1}mg^{-1}$ 이었고, 이 효소는 $Cd^{2+},\;Co^{2+},\;Fe^{2+},\;Hg^{2+},$ EDTA, 2-mercaptoethanol에 의해 강하게 억제되었다.