• Microbiology and Biotechnology Letters
• /
• v.43 no.4
• /
• pp.357-366
• /
• 2015

Quorum sensing (QS) is involved in the process of cell-to-cell communication and as a gene regulatory mechanism, which has been implicated in bacterial pathogenicity. Bacteria use this QS system to control a variety of physiological processes. In this study, pomegranate (Punica granatum L.) peel extract (PPE) was first screened for its ability to inhibit QS in bio-reporter strains (Chromobacterium violaceum and C. violaceum CV026). Next, the ability of PPE to inhibit swimming motility and biofilm formation was examined in Y. enterocolitica. Additionally, changes in the expression of specific genes involved in the synthesis of the N-acylhomoserine lactones (AHLs; yenI and yenR) and in the flagellar regulon (fliA, fleB and flhDC) were evaluated by reverse transcription (RT)-PCR. The results show that PPE specifically inhibited and reduced QS-controlled violacein production by 78.5% in C. violaceum CV026, and decreased QS-associated biofilm formation and swimming motility in Y. enterocolitica without significantly affecting bacterial growth. These inhibitory effects were also associated with the down-regulation of gene expression involved in the synthesis of AHLs and in motility. Our results suggest that PPE could be a potential therapeutic agent to prevent enteropathogens in humans, as well as highlight the need to further investigate the in vivo properties of PPE for clinical applications.

• 한국생물공학회:학술대회논문집
• /
• 2001.11a
• /
• pp.545-548
• /
• 2001

Microbiologically influenced corrosion (MIC) of metal is common in the natural environment and sulfate reducing bacteria are representative microorganisms for MIC. We found that biofilm fomlation by SRB on the metal surface might be controlled by quorum sensing, which is a cell density dependent regulation of cell metabolism. As cell free culture fluids (spent media) of Desulfovibrio vulgaris and D. desulfuricans were tested for quontrn sensing related test strains, it was found that spent media of two SRB induced increased luminescence of Vibrio harveyi BB886 (sensor 1+, sensor 2-) and BB170 (sensor 1-, sensor 2+). Quorum activities of D. vulgaris and D. desulfuricans appeared to be parallel to growth patterns, i.e., it was low in the lag phase, highly increased in the exponential phase, and reached maximum in the stationary phase. Interestingly, however, luminescence of V. harveyi BB886 and BB170 induced by a unit cell mass of the SHB showed a maximal peak in the late lag phase. Hence, it was suspected that quorum sensing of these two SHB play unknown roles in shifting cells from dormant to growth stages.

• Proceedings of the KAIS Fall Conference
• /
• 2009.12a
• /
• pp.498-500
• /
• 2009

본 연구에서는 한국인 아동의 우식치아로부터 분리한 S. mutans K7으로부터 HtrA gene을 동정하고 HtrA expression이 산성환경하에서 S. mutans의 생육에 미치는 영향을 알아보았다. S. mutans K7의 HtrA mutant strain은 산성환경에서 parental strain과 비교하였을 때, 생육에 있어서 상당한 차이를 나타내었다. 또한 Biofilm formation에 관여하는 GtfB, 와 GtfC의 발현량도 현저히 줄어들었다. 그리고 HtrA mutant strain에 HtrA gene을 삽입하여 HtrA의 발현량을 회복하였을 경우에는 acid stress하에서 control과 같은 nomal growth phenotype을 회복하였다. 이러한 결과들은 S. mutans K7에서 HtrA가 acid stress동안에 중요한 역할을 담당함을 제시하고 있다.

• KSBB Journal
• /
• v.15 no.5
• /
• pp.474-481
• /
• 2000

The effects of growth substrates such as toluene and phenol on cometabolic biodegradation of trichloroethylene (TCE) by Burkholderia cepacia G4 were investigated. The dual effects of primary substrate on TCE biodegradation, stimulatory effects of toluene and phenol at low concentrations (0.5∼2 ppm & 0.1∼0.5 ppm, respectively) and a competitive inhibition at high concentration, were observed in batch experiments. These stimulatory effects of toluene and phenol were found to be due to the increments in the amount of reducing power like NADH which could be generated during the assimilation of toluene and phenol as the carbon and energy source. The efficiency of TCE biodegradation in trickling biofilm reactor (TBR) could be also enhanced up to the TCE removal efficiency of 58.1% by the supply of appropriate amounts of phenol (0.94∼4.7 ppm).

• Journal of Korean Society of Water and Wastewater
• /
• v.27 no.6
• /
• pp.689-701
• /
• 2013

Bacterial growth and corresponding consumption of carbon and phosphorus were examined in which tap water samples containing a very low concentration of free chlorine were supplemented with organic carbon and/or phosphorus. The experiments were performed in a fed-batch mode under a controlled temperature of $20^{\circ}C$. In the phosphorus alone-added water, there was no significant increase in bacterial numbers measured as heterotrophic plate count (HPC) in the bulk water. However, bacterial growth was stimulated by the addition of carbon (e.g., bulk HPC levels increased to $10^3CFU/mL$) and further stimulated by the combined addition of carbon and phosphorus (e.g., bulk HPC to $10^5CFU/mL$). The same effects were observed in biofilm HPC and biomass formed on polyethylene (PE) slide surfaces. In the water where organic carbon and phosphorus were added together, the highest biofilm HPC and biomass (measured as extracellular polymeric substance components) densities were observed which were $7.6{\times}10^5CFU/cm^2$ and $5.3{\mu}g/cm^2$, respectively. In addition to the bacterial growth, additions of organic carbon and/or phosphorus resulted in different bacterial carbon-to-phosphorus (C/P) consumption ratios. Compared to a typical bacterial C/P consumption ratio of 100:1, a higher C/P ratio (590:1) occurred in the carbon alone-added water, while a lower ratio (40:1) in phosphorus alone-added water. Comparative value (80:1) of C/P ratio was also observed in the water where organic carbon and phosphorus were added together. At the given experimental conditions, bacterial growth was deemed to be more sensitive to microbially available organic carbon than phosphorus. The effect of phosphorus addition, which resulted in a lower C/P consumption ratio, seemed to be tightly associated with the presence of microbially available organic carbon. These results suggested that the control of extrinsic carbon influx seemed to be more important to minimize bacterial regrowth in drinking water system, since even low content of phosphorus naturally occurring in drinking water was enough to allow a bacterial growth.

• Journal of the Society of Cosmetic Scientists of Korea
• /
• v.46 no.1
• /
• pp.23-29
• /
• 2020

The skin is colonized by a large number of microorganisms with a stable composition of species. However, disease states of skin such as acne vulgaris, psoriasis, and atopic dermatitis have specific microbiome compositions that are different from those of healthy skin. The target modulation of the skin microbiome can be a potential treatment for these skin diseases. Quorum sensing (QS), a bacterial cell-cell communication system, can control the survival of bacteria and increase cell density. Also, QS affects the pathogenicity of bacteria such as biofilm formation and protease production. In this study, we confirmed anti-QS activity of Amorepacific patented ingredients, which are Lactobacillus ferment lysate (using Lactobacillus plantarum APsulloc 331261, KCCM 11179P) through bio-reporter bacterial strain Chromobacterium violaceum. The purple pigment production of C. violaceum controlled by QS was reduced 27.3% by adding 10 ㎍/mL of Lactobacillus ferment lysate (freeze dried). In addition, the Lactobacillus ferment lysate increased growth of Staphylococcus epidermidis 12% and decreased growth of Pseudomonas aeruginosa 38.5% and its biofilm formation 17.7% at a concentration of 10 ㎍/mL compared to the untreated control group. Moreover, S. epidermidis was co-cultured with the representative dermatological bacterium Staphylococcus aureus in the same genus, the growth of S. epidermidis was increased 134 % and the growth of S. aureus was decreased 13%. These results suggest that fermented lysate using Lactobacillus plantarum APsulloc 331261 may be useful as a cosmetic ingredient that can control the balance of skin microbiome.

• Journal of Korean Society of Environmental Engineers
• /
• v.29 no.4
• /
• pp.452-459
• /
• 2007

Nutrient removal hybrid process to use suspended and attached growth microorganisms and apply the contact and stabilization process was process obtaining good results to HRT within 6 hours to dominate nitrifier and to promote separation and growth of autotrophs and heterotrophs to pack with EPS(Expanded Poly-Styrene) media in nitrification reactor. An average effluent quality of this process was below 5.2 mg/L, 7.3 mg/L, 4.9 mg/L as $BOD_5,\;COD_{Mn}$, SS concentration and 6.8 mg/L, 0.6 mg/L as T-N, T-P concentration. Also, An average removal efficiency of this process was 94.6%, 79.8%, 94.9% as $BOD_5,\;COD_{Mn}$, SS and 70.8%, 76.9% as T-N, T-P. 16S-rRNA analysis result of microorganisms attached to EPS media was researched Nitrosomonas and Nitrosococcus blown to ammonia-oxidizing bacteria cluster to include Gallionella and these microorganisms were researched to involve about 6% of biofilm attached EPS media. Consequently, this process was treated below 10 mg/L and 1.0mg/L as T-N, T-P concentration at short hydraulic retention time(about 6 hr) to dominate nitrifier.

• Journal of Environmental Science International
• /
• v.11 no.9
• /
• pp.971-977
• /
• 2002

The isolated strain, Rhodococcus sp. EL-GT was able to degrade high phenol concentrations up to 10 mM within 24 hours in the medium consisting of 5.3 mM $KH_2PO_4$. 95 mM $Na_2HPO_4$, 18mM $NH_4NO_3$, 1 mM $MgSO_4{\cdot}7H_2O$,\;50{\mu}M CaCl_2$,\;0.5 {\mu}M FeCl_3$, initial pH 8.0, temperature $30^{\circ}C$ in rotary shaker at 200 rpm. This strain was good cell growth and phenol degradation in the alkaline pH range range, and the highest in the pH range of 7 to 9. The microorganism was able to grow at the various chlorinated phenols, benzene, toluene, and bunker-C oil. As Rhodococcus sp. EL-GT was good capable of attachment on the acryl media, it would be used as microorganism to consist of biofilm in wastewater treatment.

• KSBB Journal
• /
• v.22 no.4
• /
• pp.191-196
• /
• 2007

This study used biofilm process, which needs simple operation, maintenance and smaller facility area than conventional activated sludge process with the small plant operation, in the treatment of increasing sewage with the rapid industrial growth. The reactor used in this study consists of one anaerobic and one aerobic chamber filled with waste ceramic and waste vinyl as media and the treated sewage was from restaurant source. The experiment was scaled up from lab. to pilot scale and lasted for about 100 days. We focused on the removal efficiency of organics, nitrogen and phosphorus with constant HRT and continuous aeration. The removal efficiency of $BOD_5$ and SS were 94.33% and 87.77% respectively, which was a satisfaction level. However the removal efficiency of $COD_{Cr}$ was 81.46% somewhat below the desired level of 90%, and that of T-N and T-P showed 71.92% and 21.10% respectively, that was below the expected value. The removal efficiency of $COD_{Cr}$ and T-N in the pilot scale was about 10% low compared with the lab.-scale.

• Journal of Life Science
• /
• v.20 no.3
• /
• pp.321-325
• /
• 2010

Among endogenous oral microflora, Streptococcus mutans plays a critical role in dental plaque formation, which mainly contributes to the development of caries and periodontal disease. Phytochemicals are plant-derived chemical compounds that have been studied as beneficial nutrients to human health. The purpose of this study was to determine the effects of phytochemicals against S. mutans. Among them, oleanolic acid (OA) and 5-(hydroxymethyl)-2-furfural (HF) from Thomson seedless raisins were tested for anti-microbial effects against various clinically important bacteria. OA inhibited the growth of Gram-positive bacteria, but not Gram-negative bacteria. However, HF did not display any antibacterial effect against any of the strains tested. OA also exhibited inhibitory effects in surface adherence and biofilm formation of S. mutans. The results suggest that OA can be utilized as a potential anti-plaque and anti-caries agent by controlling the physiological characteristics of S. mutans on teeth.