• Journal of Microbiology
• /
• v.44 no.2
• /
• pp.226-232
• /
• 2006

Swarming has proven to be a good in vitro model for bacterial surface adherence and colonization, and the swarming differentiation of a bacterium has been shown to be coupled with changes in the expression of virulence factors associated with its invasiveness, particularly in the early stages of infection. In this study, we attempted to determine whether the expression of vvhA, which encodes for hemolysin/cytolysin (VvhA), is either upregulated or downregulated during the swarming differentiation of V. vulnificus. The insertional inactivation of vvhA itself exerted no detectable effect on the expression of V. vulnificus swarming motility. However, in our lacZ-fused vvhA transcriptional reporter assay, vvhA expression decreased in swarming V. vulnificus as compared to non-swarming or planktonic V. vulnificus. The reduced expression of vvhA in swarming V. vulnificus increased as a result of the deletional inactivation of luxS, a gene associated with quorum sensing. These results show that vvhA expression in swarming V. vulnificus is downregulated via the activity of the LuxS quorum-sensing system, suggesting that VvhA performs no essential role in the invasiveness of V. vulnificus via the adherence to and colonization on the body surfaces required in the early stages of the infection. However, VvhA may playa significant role in the pathophysiological deterioration occurring after swarming V. vulnificus is differentiated into planktonic V. vulnificus.

• Proceedings of the Plant Resources Society of Korea Conference
• /
• 2018.04a
• /
• pp.53-53
• /
• 2018

전라북도 동부권 지역은 중산악지형으로 표고 100~500m 산지가 69%, 500~1,000m가 26%로 이루어져 있어, 산채를 재배하기에 유리한 지리적 조건을 갖고 있다. 따라서 소비자의 수요가 높은 산채류의 재배 및 이용에 대한 농업인들의 기술개발이 요구되고 있다. 이에 전라북도 준고랭지역에서 재배하기 적합한 산채작목을 선발하고자 본 시험을 실시하였다. 시험은 표고 500m 전라북도 남원시 운봉읍 허브시험장에서 노지재배, 남원시 주천면 표고 530~540m, 진안군 주천면 표고 340~350m에 위치한 농가포장에서 임간재배를 실시하였다. 대상작물은 개미취(Aster tataricus), 갯기름나물(Peucedanum japonicum), 곤달비(Ligularia stenocephala), 눈개승마(Aruncus dioicus var. kamtschaticus), 단풍취(Ainsliaea acerifolia), 산마늘(Allium microdictyon), 섬쑥부쟁이(Aster glehnii), 어수리(Heracleum moellendorffii), 우산나물(Syneilesis palmata) 등 9종을 2016년 종묘를 정식하였다. 정식 2년차에 해당지역의 5월~9월 평균기온 및 조도 등 생육환경을 조사하고, 시험작물의 출현율, 생육특성, 수량 등을 조사하였다. 조사기간 동안의 평균기온은 노지가 $20.8^{\circ}C$, 남원임간은 $20.3^{\circ}C$, 진안임간은 $20.5^{\circ}C$이었으며, 평균조도는 노지가 37,362Lux, 남원임간은 7,816Lux, 진안임간은 25,316Lux이었다. 노지에서 출현율은 개미취, 갯기름나물, 눈개승마, 산마늘, 섬쑥부쟁이, 우산나물이, 임간에서는 개미취, 곤달미, 눈개승마, 단풍취, 산마늘, 어수리, 우산나물이 높았다. 생육특성은 노지에서 개미취, 갯기름나물, 눈개승마, 섬쑥부쟁이, 임간에서는 단풍취, 산마늘, 우산나물의 생육이 좋았다. 수량은 노지에서 개미취, 갯기름나물, 곤달비, 산마늘, 섬쑥부쟁이, 어수리가 높았으며, 남원임간에서는 곤달비, 단풍취, 우산나물, 어수리가, 진안임간에서는 개미취, 갯기름나물, 산마늘, 우산나물의 수량이 많았다. 이와 더불어 준고랭지에 적합한 산채류률 선발하기 위해서는 차후 재배 지역 및 방법의 차이에 따른 산채작물의 연차별 수량성과 경제성에 관한 연구가 이루어져야 할 것으로 여겨진다.

• Journal of Microbiology
• /
• v.38 no.3
• /
• pp.117-121
• /
• 2000

Recent advances in studies of bacterial gene expression and light microscopy show that cell-to cell communication and communication and community behavior are the rule rather than the exception. One type of cell-cell communication, quorum sensing in Gram-negative bacteria involves acyl-homoserine lactone signals. This type of quorum sension represents a dedicated communication system that enables a given species to sense when it has reached a critical population density. and to respond by activating expression of specific genes. The LuxR and LuxI proteins of Vibrio fisheri are the founding members of the acyl-homoserine lactone quorum sensing signal receptor and signal generator families of proteins. Acyl-homeserine lactone signaling in Pseudomonas aeruginosa is one model for the relationship between quorum sensing community behavior, and virulence. In the P. aeruginosa model. quorum sensing is required for normal biofilm maturation and virulence. There are multiple quorum-sensing circuits that control the expression of dozens of specific genes in P. aeruginosa.

• KSBB Journal
• /
• v.6 no.4
• /
• pp.351-361
• /
• 1991

This study is on the investigation of hydrogen production and substrate removal by photosynthetic bacteria. After using of Rhodospillum rubrum KS-301 and IFO 3986, which are photosynthetic bacteria as strains, R. rubrum KS-301 was turned out a better strain. And result of experiment in which glucose and sodium lactate, components of wastewater, were used limiting substrates, showed that the productivity of hydrogen was indifferent with the kind of substrates. In batch experiments using free cells and immobilized whole cells, the decrease in hydrogen productivity was observed in the latter case. From the results of these experiments, specific growth rate of cells, specific utilization rate of glucose, and specific production rate of hydrogen were calculated. And each rate was expressed in the form of Monod equation of which parameters were estimated. Also the optimum condition of hydrogen production for free cells was $30^{\circ}C$, pH 7, and 12,000 Lux, and the optimum immobilized condition was as follows: initial immobilized cell concentration 1.0g/L, sodium alginate concentration 2% and light intensity 12,000 Lux.

• Journal of Microbiology and Biotechnology
• /
• v.26 no.1
• /
• pp.66-71
• /
• 2016

PikD is a widely known pathway-specific regulator for controlling pikromycin production in Streptomyces venezuelae ATCC 15439, which is a representative of the large ATP-binding regulator of the LuxR family (LAL) in Streptomyces sp. RapH and FkbN also belong to the LAL family of transcriptional regulators, which show greatest homology with the ATP-binding motif and helix-turn-helix DNA-binding motif of PikD. Overexpression of pikD and heterologous expression of rapH and fkbN led to enhanced production of pikromycin by approximately 1.8-, 1.6-, and 1.6-fold in S. venezuelae, respectively. Cross-complementation of rapH and fkbN in the pikD deletion mutant (ΔpikD) restored pikromycin and derived macrolactone production. Overall, these results show that heterologous expression of rapH and fkbN leads to the overproduction of pikromycin and its congeners from the pikromycin biosynthetic pathway in S. venezuelae, and they have the same functionality as the pathwayspecific transcriptional activator for the pikromycin biosynthetic pathway in the ΔpikD strain. These results also show extensive "cross-communication" between pathway-specific regulators of streptomycetes and suggest revision of the current paradigm for pathwayspecific versus global regulation of secondary metabolism in Streptomyces species.

• Microbiology and Biotechnology Letters
• /
• v.50 no.1
• /
• pp.1-14
• /
• 2022

Bacteria communicate with each other through an intricate communication mechanism known as quorum sensing (QS). QS regulates different behavioral aspects in bacteria, such as biofilm formation, sporulation, virulence gene expression, antibiotic production, and bioluminescence. Several different chemical signals and signal detection systems play vital roles in promoting highly efficient intra- and interspecies communication. Gram-negative bacteria coordinate gene regulation through the production of acyl homoserine lactones (AHLs). Gram-positive bacteria do not code for AHL production, while some gram-negative bacteria have an incomplete AHL-QS system. Despite this fact, these microbes can detect AHLs owing to the presence of LuxR solo receptors. Various studies have reported the role of AHLs in interspecies signaling. Moreover, as bacteria live in a polymicrobial community, the production of extracellular compounds to compete for resources is imperative. Thus, AHL-mediated signaling and inhibition are considered to affect virulence in bacteria. In the current review, we focus on the synthesis and regulation mechanisms of AHLs and highlight their role in interspecies bacterial signaling. Exploring interspecies bacterial signaling will further help us understand host-pathogen interactions, thereby contributing to the development of therapeutic strategies intended to target chronic polymicrobial infections.

• Science of Emotion and Sensibility
• /
• v.16 no.2
• /
• pp.195-206
• /
• 2013

The main causes of traffic accidents while driving a car is of the driver's visual distraction. In this study, the color sensitivity of the information projected on the windshield were evaluated for HUD (Head Up Display) system which helps the driver's eyes on the road while driving. The driving Information were projected $9^{\circ}$ downward from front sight $0^{\circ}$ under lab's fluorescent lights, LED floorlights and the TV had having 25 [lux] illumination when driving at night environment and 100,000 [lux] of daylight environment. Munsell color hue of the basic five colors (R, Y, G, B, P) and the color of traffic lights YR, W were the color of the seven characters, each character were outlined by White, Gray except for W. Total of 19 experimental stimuli was shown in the environment of day and night driving for asking visibility information of color, fatigue, preferences, and evaluate the degree of interference. The results came out that the bright Y and G color is visibility significantly for daylight. Second, with the outline of the text, the color of the outline works as a background for luminance contrast effects and affects visibility. Third, without the outline, the glass in front of the vehicle acts as the background and the luminance contrast of characters achieve greater brightness and visibility. The luminance contrast between the stimuli and background should be considered for increasing color visibility for driving information which is an important factor for HUD commercialization.

• Journal of Microbiology and Biotechnology
• /
• v.13 no.3
• /
• pp.477-481
• /
• 2003

The community escape response of Rhodobacter sphaeroides is exerted through the action of CerR and CerI, which code for a LuxR-type regulatory protein and acylhomoserine lactone synthase, respectively. Deletion of chromosomal DNA including cerR and cerI (mutant RI) or insertional interruption of cert (mutant AP3) resulted in two-fold increase in the cellular poly-${\beta}$-hydroxybutyrate (PHB) content In comparison with the wild-type under aerobic growth conditions. The PHB synthase (PhbC) activities of the cer mutants were doubled, and the enzyme expression was regulated at the level of phbC transcription. Thus, CerR, possibly in response to autoinducer (AI), appears to modulate the PHB content of aerobically grown cells by downregulating phbC transcription.

• Journal of Microbiology and Biotechnology
• /
• v.26 no.1
• /
• pp.139-144
• /
• 2016

Synthetic oscillators are gene circuits in which the protein expression will change over time. The delay of transcription, translation, and protein folding is used to form this kind of behavior. Here, we tried to design a synthetic oscillator by a negative feedback combined with a positive feedback. With the mutant promoter P_LacC repressed by LacIq and P_Lux activated by AHL-bound LuxR, two gene circuits, Os-LAA and Os-ASV, were constructed and introduced into LacI-deleted E. coli DH5α cells. When glucose was used as the carbon source, a low level of fluorescence was detected in the culture, and the bacteria with Os-ASV showed no oscillation, whereas a small portion of those carrying Os-LAA demonstrated oscillation behavior with a period of about 68.3 ± 20 min. When glycerol was used as the carbon source, bacteria with Os-ASV demonstrated high fluorescence value and oscillation behavior with the period of about 121 ± 21 min.

• Journal of Microbiology and Biotechnology
• /
• v.16 no.7
• /
• pp.1125-1131
• /
• 2006

A kan'::luxCDABE fusion strain that was both highly bioluminescent and responsive to benzoic acid was constructed by transforming E. coli strain W3110 with the plasmid pUCDK, which was constructed by digesting and removing the 7-kb KpnI fragment from the promoterless luxCDABE plasmid pUCD615. Experiments using buffered media showed that this induction was dependent on the pH of the media, which influences the degree of benzoic acid protonation, and the expression levels seen are likely due to acidification of the cytoplasm by uncoupling of benzoic acid. Consequently, the sensitivity of this strain for benzoic acid was increased by nearly 20-fold when the pH was shifted from 8.0 to 6.5. Benzoic acid derivatives and several phenolics also resulted in significantly increased bioluminescent signals. Although these compounds are known to damage membranes and induce the heat-shock response within E. coli, bacterial strains harboring mutations in the fadR and rpoH genes, which are responsible for fatty acid biosynthesis during membrane stress and induction of the heat-shock response, respectively, showed that these mutations had no effect on the responses observed.