Role of LuxIR Homologue AnoIR in Acinetobacter nosocomialis and the Effect of Virstatin on the Expression of anoR Gene

( Man Hwan Oh ),( Chul Hee Choi ) 한국미생물 · 생명공학회 2015 Journal of microbiology and biotechnology Vol.25 No.8

Quorum sensing is a process of cell-to-cell communication in which bacteria produce autoinducers as signaling molecules to sense cell density and coordinate gene expression. In the present study, a LuxI-type synthase, AnoI, and a LuxR-type regulator, AnoR, were identified in Acinetobacter nosocomialis, an important nosocomial pathogen, by sequence analysis of the bacterial genome. We found that N-(3-hydroxy-dodecanoyl)-L-homoserine lactone (OH-dDHL) is a quorum-sensing signal in A. nosocomialis. The anoI gene deletion was responsible for the impairment in the production of OH-dDHL. The expression of anoI was almost abolished in the anoR mutant. These results indicate that AnoI is essential for the production of OH-dDHL in A. nosocomialis, and its expression is positively regulated by AnoR. Moreover, the anoR mutant exhibited deficiency in biofilm formation. In particular, motility of the anoR mutant was consistently and significantly abolished compared with that of the wild type. The deficiency in the biofilm formation and motility of the anoR mutant was significantly restored by a functional anoR, indicating that AnoR plays important roles in the biofilm formation and motility. Furthermore, the present study showed that virstatin exerts its effects on the reduction of biofilm formation and motility by inhibiting the expression of anoR. Consequently, the combined results suggest that AnoIR is a quorum-sensing system that plays important roles in the biofilm formation and motility of A. nosocomialis, and virstatin is an inhibitor of the expression of anoR.

공주 공산성 원형연못의 지반에 대한 탄성파 굴절법 탐사

오진용,변성환,서만철 공주대학교 문화재보존과학연구소 2004 문화재과학기술 Vol.3 No.1

탄성파 탐사는 인공지진파를 이용하여 지표면 하부의 물성을 알아내는 지구물리탐사로서 20세기 초부터 석유탐사와 공학적 지반조사에 가장 널리 사용되었다. 굴절법 탄성파 탐사는 지층의 탄성파 속도를 알아내는 방법으로서 최근에는 석조문화재 등의 지반특성 조사에서 사용된 예가 있다. 이번 연구에서는 공주 공산성의 쌍수정 광장에 위치하는 공산성 원형연못 주변의 지반에 대하여 굴절법 탐사를 실시하였다. 쌍수정 광장은 기본의 발굴조사를 통하여 백제 추정왕궁지가 위치한 곳으로 알려졌으며, 광장 남쪽에 원형연못(상면직경 7.3m, 바닥직경 4.78m, 높이 3m)도 발굴되었다. 원형연못 주변에 5개 탄성파 측선을 설치하였고, 해머 타격점과 수신기 배열을 3가지 다른 방식을 적용하여 24m, 31m, 48m 측선길이의 굴절법 자료를 얻었다. 대체로 공산성 원형연못 주변의 지반은 3개 층으로 구성되어 있다. 각 층의 겉보기 속도는 약 261~391 m/s, 약 591~992m/s, 약 1950~3230 m/s이며, 첫 번째와 두 번째 측의 두께는 각각 약 2~2.4m 와 4.6~8.6m이다. 일반적으로 최하부 층의 속도는 기반암, 상부층들이 속도는 풍화토에 대응한다. 그러나 두 번째 층이 주시곡선 형태와 속도 범위는 국내 석탑 문화재 하부의 것과 유사한 것으로 보아 공산성 연못 주변은 인공적인 기초지반의 가능성을 제기하며, 그렇다면 공산성 원형연못은 파내려 간 것보다는 쌓아 올렸을 것이다. Seismic survey using artificial earthquake waves is one of the most popular geophysical method for petroleum exploration and engineering prospecting from the early 20th century. Recently seismic refraction method which can reveal the sub-surface velocity structure is introduced for the site characterization of the domestic stone pagodas. The purpose of this study is to understand seismic velocity structures of the underground near the Kongsansung Cirular Pond at the southern part of the Ssangsujung Park in Gongju. As the result of early excavations, the Ssangsujung Park has been known as the assumed site of the Palace of the Paekje Dynasty and Circular Pond (top diameter 7.3 m, bottom diameter 4.78m, and height 3m) was also discovered. Along 3 seismic lines near the Circular Pond, three kinds of source-receiver array are applied to obtain the refraction data with the corresponding maximum offset of 24m, 31m, and 48m. Shallow subsurface near the Circular Pond largely consists of three layers with the velocities of about 261~392 m/s, about 591~992 m/s, about 1950~3230 m/s, respectively. Upper two layers have the thickness of about 2~2.4 m and about 2.6~8.6 m each. In general, the bottom layer can be interpreted to the basement, and the upper layers with the lower velocities can be correlated to the weathered soil. Compared with the pattern of the traveltime-distance graph and the range of the velocities of the site near domestic stone pagodas, however, the middle layer can be interpreted as the artificial foundation. Consequently, the Kongsansung Circular Pond is possibly built upwardly rather than digging.

Proteomic Identification and Characterization of Vibrio vulnificus Proteins Induced upon Exposure to INT-407 Intestinal Epithelial Cells

( Man Hwan Oh ),( Hee Gon Jeong ),( Sang Ho Choi ) 한국미생물 · 생명공학회 2008 Journal of microbiology and biotechnology Vol.18 No.5

AbaR is a LuxR type regulator essential for motility and the formation of biofilm and pellicle in Acinetobacter baumannii

Man Hwan Oh,Kyudong Han 한국유전학회 2020 Genes & Genomics Vol.42 No.11

Background Acinetobacter baumannii is a major opportunistic pathogen causing nosocomial infections. Acinetobacter baumanniipossesses a quorum sensing system consisting of abaI, encoding an autoinducer synthase, and abaR, encoding aputative LuxR type regulator. AbaI is required for motility and biofilm formation in A. baumannii. However, the functionsof AbaR on the expression of abaI, motility, and the formation of biofilm and pellicle have not yet been explored. Objective The aim of this study was to investigate the effects of abaR mutation on the expression of abaI, motility, and theformation of biofilm and pellicle. Methods Functions of AbaR were assessed by the construction of an isogenic mutant and by evaluating the effects of abaRmutation on the expression of abaI, motility, and the formation of biofilm and pellicle. Results The abaR mutant revealed a significant decrease in the expression of abaI. The disruption of abaR resulted in substantialdefects in motility and the formation of biofilm and pellicle. Introduction of abaR in trans complemented the defects. Conclusions AbaR of A. baumannii is required for the expression of abaI and plays important roles in motility and the formationof biofilm and pellicle. AbaR may be considered to be a target of anti-biofilm agents.

Regulation of the Vibrio vulnificus hupA Gene by Temperature Alteration and Cyclic AMP Receptor Protein and Evaluation of Its Role in Virulence

Oh, Man Hwan,Lee, Sung Min,Lee, Dong Hwan,Choi, Sang Ho American Society for Microbiology 2009 Infection and immunity Vol.77 No.3

<B>ABSTRACT</B><P>Availability of free iron is extremely limited in the mammalian host, and the acquisition of iron in the host is essential for successful infection by pathogenic bacteria. Expression of many genes involved in acquiring iron is regulated in response to the level of iron availability, and iron regulation is mediated by Fur. In this study, cellular levels of <I>Vibrio vulnificus</I> HupA, a heme receptor protein, and the <I>hupA</I> transcript were found to increase in cells grown at 40°C compared to cells grown at 30°C. The results suggested that change in growth temperature, in addition to iron availability, is an environmental cue controlling the expression of the <I>hupA</I> gene. The influence of global regulatory proteins on the expression of <I>hupA</I> was examined, and the cyclic AMP receptor protein (CRP) was found to activate the expression of <I>hupA</I> at the transcriptional level. CRP exerts its effects by directly binding to DNA upstream of the <I>hupA</I> promoter P<I>hupA</I>, and a CRP binding site, centered at 174 bp upstream of the transcription start site, was identified by a DNase I protection assay. Finally, a <I>hupA</I> mutant showed reduced virulence in mice and in tissue cultures, in which growth of the <I>hupA</I> mutant was impaired, indicating that HupA of <I>V. vulnificus</I> is essential for survival and multiplication during infection.</P>

The effect of ISAba1-mediated adeN gene disruption on Acinetobacter baumannii pathogenesis

Oh, Man Hwan,Choi, Chul Hee,Lee, Je Chul Taylor Francis 2017 Virulence Vol.8 No.7

기반 기술 : 주석 도금한 커넥터의 접촉 하중의 변화에 의한 전기 접촉저항 변화에 관한 연구

유환신 ( Hwan Shin Yu ),오만진 ( Man Jin Oh ),박형배 ( Hyung Bae Park ),유환신 ( Hwan Shin Yu ),오만진 ( Man Jin Oh ),박형배 ( Hyung Bae Park ) 한국항행학회 2014 韓國航行學會論文誌 Vol.18 No.4

전기 커넥터에 영향을 주는 프레팅 부식 요인 중 하나인 접촉 부하의 영향을 조사하기 위하여, 프레팅 부식 표본 쌍을 두께 3μm의 두께를 갖는 주석으로 도금된 황동 표본을 사용하여 제조하였다. 접점의 전기저항은 프레팅 부식 시험 기간 동안 측정되었다. 프레팅 주기에서 저항은 증가하였다. 저항의 변화는 3단계로 나눌 수 있다. 첫 번째 단계는 미미하고 안정적인 저항을 나타내었다. 두 번째 단계는 저항이 꾸준한 증가를 보여 주었다. 그리고 세 번째 단계는 매우 높고 간헐적인 저항을 보여주었다. 실패주기(Nf)와 접촉력(P) 사이의 관계는 다음과 같이 표현될 수 있다. 각각의 하중, 변위, 온도 등 다양한 조건에서 프레팅 테스트를 통해 다양한 환경 조건 하에서 매우 높고 간헐적인 저항에 대응 전기 커넥터의 실패주기 예측공식의 표현이 가능할 것이다. In order to investigate the effect of contact load, which is one of the fretting corrosion factors affecting the electric connector, a coupled fretting corrosion specimens were prepared using a tin-plated brass coupon with a thickness of 3 μm. Electric resistance of the contact was measured during the fretting corrosion test period. There was increase in resistance with fretting cycles. The change in resistance can be classified by 3 stages. The first stage exhibited low and stable resistance. Second stage showed steady increment of the resistance and third stage showed very high and intermittent resistance. The relationship between the failure cycle (Nf) and contact force (P) can be drawn as; It is possible to draw the prediction equation for the failure cycle of the electric connector corresponding to the very high and intermittent resistance under various environment conditions through the fretting tests under various conditions such as load, displacement, temperature.

맹종죽 죽순 장아찌 숙성 중 품질 특성 변화

오철환 ( Chul Hwan Oh ),오남순 ( Nam Soon Oh ),원선임 ( Sun Im Won ),인만진 ( Man Jin In ),김동청 ( Dong Chung Kim ) 한국산업식품공학회 2013 산업 식품공학 Vol.17 No.2

수분함량이 높아 상온에서 쉽게 변질되는 죽순은 유익한 효능 때문에 다양한 조리방법으로 소비되고 있으나 식품산업에서 가공식품으로의 활용은 대단히 미흡하다. 본 연구는 맹종죽순의 활용도를 높이기 위하여 죽순 장아찌를 검토하였다. 장아찌 제조를 위한 죽순의 전처리 조건과 고추장과 간장을 절임원으로 사용한 장아찌의 숙성과정 중 품질 특성의 변화를 조사하였으며, 이를 토대로 죽순 장아찌의 전체적인 제조공정을 제안하였다. 죽순의 전처리는 죽순을 100℃ 열수로 30분간 처리하여 연화시킨 후 10% NaCl 용액에 1시간 침지시켜 아린 맛 성분을 제거하고 50℃로 8시간 건조시키는 것이 장아찌 제조에 적합하였다. 전처리 된 죽순을 간장과 고추장을 이용하여 장아찌를 제조한 후 25℃에서 숙성시키며 이화학적 특성과 관능특성의 변화를 조사하였다. 숙성과정에서 간장장아찌외 고추장장아찌의 pH는 큰 변화 없이 pH 4.0∼5.5 범위에서 유지되었으며, 고추장장아찌는 염도가 다소 증가하였다. 두 장아찌의 색은 숙성되면서 명도와 황색도가 낮아졌으며 고추장장아찌는 적색도가 증가하였다. 두 장아찌의 관능적인 특성 중 색, 맛, 아삭한 조직감, 전체적인 기호도은 숙성기간에 비례하여 향상되었으며, 관능적으로 숙성기간은 6일이 적합하였다. To develop red pepper paste and soy sauce pickles with Maengjong bamboo (Phyllostachys pubescens) shoots, the pretreatment conditions of bamboo shoots and the physicochemical and sensory properties of both pickles according to incubation period were investigated. For pretreatment, wet heating in boiling water was more effective to soften the fresh bamboo shoots than dry heating at 190℃. To remove the disagreeable pungent taste of the shoots, the heated shoots were soaked in 10% NaCl solution for 1 hour and dried at 50℃ for 8 hours. Changes of the quality characteristics of the red pepper paste and soy sauce pickles using pretreated bamboo shoots were observed at 25℃ for 6 days. The pH of both of the pickles was stably maintained at 4.0∼5.5 for 6 days. The salt value of the red pepper paste pickles considerably increased from 7.21% to 9.36%. The lightness and yellowness of the color values of both pickles decreased and the redness of the red pepper paste pickles increased with increase of the incubation time. The sensory evaluation, color, taste, texture, and overall acceptability of both pickles were enhanced with increase of the incubation time. Further, the proper incubation period for both pickles was suggested to be 6 days.

Saccharomyces cerevisiae와 Leuconostoc mesenteroides 균주의 혼합배양으로 제조한 증편용 Rice Sourdough의 특성

오철환(Chul-Hwan Oh),인만진(Man-Jin In),오남순(Nam-Soon Oh) 한국식품영양과학회 2008 한국식품영양과학회지 Vol.37 No.5

본 연구는 빵의 스폰지법을 증편의 제조에 응용하기 위한 pre-fermented rice sourdough의 제조조건을 확립하고자 수행되었다. Rice sourdough를 제조하기 위하여 S. cerevisiae CY 균주와 L. mesenteroides ATCC 9135 균주를 접종하여 30℃에서 24시간 동안 발효시키면서 rice sourdough의 품질 특성을 조사하였다. 반죽에서 L. mesenteroides 균주의 생육은 초기에 감소하다가 배양 후기에 증가하는 경향을 보였으며, S. cerevisiae 균주는 전형적인 효모의 생육곡선을 보였다. 효모와 유산균의 혼합배양으로 반죽에 존재하는 총균수는 감소되었다. 또한 혼합배양으로 반죽의 점도와 팽창도는 증가되었으며, 팽창도인 경우 18시간 발효 후 170%의 증가를 보였다. 혼합배양 시 현미분의 첨가는 유기산과 에탄올의 생성을 촉진시켰으며, 발효제품의 기호성을 평가하는 fermentation quotient(FQ; lactic acid와 acetic acid의 몰비)는 1.9~3.2로 양호하였다. 이는 S. cerevisiae 균주와 L. mesenteroides 균주의 혼합배양으로 제조한 rice sourdough가 향후 증편 제조용 발효종으로 사용될 경우 증편의 품질향상에 기여할 것으로 생각된다. The aim of this work was to investigate the microbiological and physicochemical properties of the rice sourdough for Jeungpyun prepared by mixed culture of Saccharomyces cerevisiae (S. cerevisiae) and Leuconostoc mesenteroides (L. mesenteroides) strains. The rice sourdough was fermented with S. cerevisiae and L. mesenteroides strains in rice dough for 24 hours at 30℃. Growth of L. mesenteroides strain was decreased after inoculation, however, it increased again after 18 hours of dough fermentation, and the growth of S. cerevisiae showed a typical growth pattern. Also, total aerobic microorganisms counts in rice sourdough were decreased due to the produced organic acids and ethanol during dough fermentation. These products led to a favorable fermentative quotient (FQ; molar ratio between lactic to acetic acid) value of 1.9~3.2 and more stable fermentation for rice sourdough formation. The expansion ratio and viscosity were considerably increased by mixed cultivation of S. cerevisiae and L. mesenteroides strains. Addition of the brown rice at 10% (w/w) to dough preparation increased the relative expansion ratio to the highest value.

전기융합법을 이용한 phytase 생성 내염성 효모 균주의 개발

오철환 ( Chul Hwan Oh ),인만진 ( Man Jin In ),오남순 ( Nam Soon Oh ) 한국응용생명화학회 2007 Applied Biological Chemistry (Appl Biol Chem) Vol.50 No.1