• Clinical and Experimental Pediatrics
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• 제64권11호
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• pp.543-551
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• 2021

The human microbiome, which consists of a collective cluster of commensal, symbiotic, and pathogenic microorganisms living in the human body, plays a key role in host health and immunity. The human nasal cavity harbors commensal bacteria that suppress the colonization of opportunistic pathogens. However, dysbiosis of the nasal microbial community is associated with many diseases, such as acute respiratory infections including otitis media, sinusitis and bronchitis and allergic respiratory diseases including asthma. The nasopharyngeal acquisition of pneumococcus, which exists as a pathobiont in the nasal cavity, is the initial step in virtually all pneumococcal diseases. Although the factors influencing nasal colonization and elimination are not fully understood, the adhesion of opportunistic pathogens to nasopharyngeal mucosa receptors and the eliciting of immune responses in the host are implicated in addition to bacterial microbiota properties and colonization resistance dynamics. Probiotics or synbiotic interventions may show promising and effective roles in the adjunctive treatment of dysbiosis; however, more studies are needed to characterize how these interventions can be applied in clinical practice in the future.

• 한국미생물·생명공학회지
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• 제49권4호
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• pp.478-484
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• 2021

Cellular resources including transcriptional and translational machineries in bacteria are limited, yet microorganisms depend upon them to maximize cellular fitness. Bacteria have evolved strategies for using resources economically. Regulatory networks for the gene expression system enable the cell to synthesize proteins only when necessary. At the same time, regulatory interactions enable the cell to limit losses when the system cannot make a cellular profit due to fake substrates. Also, the architecture of the gene expression flow can be advantageous for clustering functionally related products, thus resulting in effective interactions among molecules. In addition, cellular systems modulate the investment of proteomes, depending upon nutrient qualities, and fast-growing cells spend more resources on the synthesis of ribosomes, whereas nonribosomal proteins are synthesized in nutrient-limited conditions. A deeper understanding of cellular mechanisms underlying the optimal allocation of cellular resources can be used for biotechnological purposes, such as designing complex genetic circuits and constructing microbial cell factories.

• 한국환경과학회지
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• 제20권7호
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• pp.899-905
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• 2011

In order to develop bacterial cellulose (BC) with antimicrobial activity against pathogenic microorganisms, silver and chitosan were incorporated into BC, respectively. Experiment results showed that antimicrobial activity against pathogenic microorganisms was improved with increasing silver concentration. Chitosan also showed a direct proportion between its concentration and antimicrobial activity. These results suggest that antimicrobial effects of BC using silver and chitosan are well proven to be effective. We also tested the stainability of BC with natural colorant for the application of food industry. Stainability of BC was enhanced with increasing natural colorant concentration. Decolorization of BC stained was observed by dipping it into distilled water with one hour-intervals. As a result, there was no significant difference. Combination of natural colorant-stainability and antibiosis of BC is expected to be useful in making colored antibiotic BC in various industrial application areas, considering its antimicrobial activity, high stainability and low decolorization tendency.

• 한국자원식물학회지
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• 제23권5호
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• pp.430-435
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• 2010

본 연구는 천연 식품보존료 개발의 일환으로 한약 재료로 이용되고 있는 개머루덩굴을 에탄올로 추출하여 식품부패 및 병원성 미생물에 대한 항균활성을 조사하였다. 개머루덩굴 에탄올 추출물은 식품부패 및 병원성 미생물에 대해 농도 의존적으로 항균효과를 보였으며, 그 중에서 Escherichia coli O157:H7 균에 대해 가장 높은 항균효과를 보였다. 또 개머루덩굴 에탄올 추출물이 식중독 유발세균의 성장에 미치는 효과를 검정하기 위해 Salmonella typhimurium, Yersinia enterocolitica, Staphylococcus aureus, Escherichia coli O157:H7 균들의 배양액에 개머루덩굴 에탄올 추출물의 농도를 250, 500, 1,000, 2,000 mg/L 각 농도별로 첨가하여 생육을 조사한 결과 250 mg/L까지는 대조군과 별 차이를 보이지 않았으나 500 mg/L 이상에서는 유의적인(p<0.05) 감소를 관찰할 수 있었다. 본 연구결과는 개머루덩굴 에탄올 추출물이 식중독을 유발시키는 세균에 대하여 우수한 항균작용을 나타내고 있으며, 따라서 개머루덩굴이 효과적인 천연보존료로서 이용될 수 있음을 시사하고 있다.

• 한국미생물·생명공학회지
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• 제7권4호
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• pp.197-204
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• 1979

계육을 이용한 가공식품개발의 필요성에 의하여 원료육의 전처리 과정중 부패에 가장 큰 영향을 미치는 미생물의 증식을 억제하고자 NaOCl과 succinic acid를 병행사용하여 미생물의 증식억제 효과 및 저장기간의 연장등을 조사한 결과는 다음과 같다. 1. NaOCl의 농도증가에 따라 미생물의 증식억제효과도도 증가하였다. 200ppm 처리시 50ppm의 경우보다 1/1000로 생존균체가 더 감소하였다. 2. 탕지 처리시 6$0^{\circ}C$에서 염소의 소실도 적었으며 규체억제 및 계육표피의 보전성에서도 양호한 결과를 얻었다. 3. NaOCl에 유기산 검가시 pH 3 부근에서 급격한 균체 억제작용을 보였다. Acetic acid, succinic acid, lactic acid, citric acid 등 유기산 첨가시 succinic 효과가 pH 3.12, 0.51%의 농도에서 균체억제 효과가 가장 좋았다. 4. 200ppm NaOCl ＋0.5% succinic acid로 30분간 침지한 계육을 5$^{\circ}C$와 -18$^{\circ}C$에 명명 저장시저장기간의 연장은 무처리군보다 5$^{\circ}C$의 경우 2일간 더 연장되었다.

• Restorative Dentistry and Endodontics
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• 제20권1호
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• pp.71-95
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• 1995

Bacteria have been regarded as a one of major etiologic factors in root canal infections. In endodontic treatment the effective removal of pathogenic microorganisms in the root canal is the key to successful outcome. Bacterial cell wall components may play an important role in the development of pulpal and periapical disease. The purpose of this study was to evaluate the effect of sonic extracts of Streptococcus spp. on cultured L929 cells and to characterize cell wall protein profiles of Streptococcus spp. Streptococcus spp. were isolated from infected root canals and identified with Vitek Systems(Biomeriux, USA). Five streptococci, namely S. sanguis, S. mitis, S uberis, S. mutans (ATCC 10449) and S. faecalis (ATCC 19433) weere enriched in brain heart infusion broth. Cell pellets were sonicated and cell wall extracts were dialyzed and membrane filtered. Prepared cell wall proteins were applied to cultured L929 cell. The cell reaction were evaluated by monitoring DNA synthesis, cell numbers and the change of cell morphology. The total cell wall protein profiles of microorganisms were characterized by sodium dodecyl sulfate polyacrylamide-gel eledruphoresis(SDS-PAGE). DNA synthesis of L929 cells were reduced by the increasing concentration of sonic extracts. DNA synthesis was significantly suppressed in more than $50{\mu}g$/ml of sonic extract conentration in five streptococci. S. nutans (ATCC 10449) showed stronger suppression on DNA synthesis than remaining four streptococci, which had the similar effect on DNA synthesis. Analysis of DNA synthesis measured by [$^3H$]-thymidine uptake was more sensitvie method than cell counting. Sonic extracts affected the microscopic findings of L929 cells. The protein profiles indicated that all five strains shared two major proteins with molecular masses of 70.8 and 57.5 kD respectively. S. uberis and S. mutans shared common minor proteins of which molecular weights were 147.9 and 112.2 kD respectively. However some minor proteins were unique for S. mitis, S. uberis and S. faecalis.

• Journal of Applied Biological Chemistry
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• 제63권2호
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• pp.125-129
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• 2020

Environmental pollution caused by various heavy metals is a serious global problem. To solve this problem, microbial bioremediation of contaminated metals has developed rapidly as an effective strategy when physical and chemical techniques are not suitable. In this study, cadmium (Cd)-tolerant soil bacteria were isolated via artificial induction in laboratory conditions instead of screening bacteria naturally adapted to metal-contaminated soils. Wild-type (WT) bacteria grown in uncontaminated soils were artificially and sequentially adapted to gradually increasing Cd concentrations of up to 15 mM. The resultant cells, named Soil-CdR15, survived at a Cd concentration of 10 mM, whereas WT cells failed to survive with 4 mM Cd on solid media for 2 d. In liquid media containing Cd, the SoilCdR15 cells grew with 15 mM Cd for 7 d, whereas the WT cells could not grow with 5 mM Cd. Both Soil-CdR15 and WT cells removed approximately 35% of Cd at the same capacity from liquid media containing either 0.5 or 1.0 mM Cd over 2 d. In addition to Cd, the Soil-CdR15 cells showed increased resistance to nickel, zinc, and arsenic compared to WT cells. The Soil-CdR cells were identified as Burkholderia sp. by partial sequencing of 16S rRNA. The data presented in this study demonstrate that isolation of heavy metal-tolerant microorganisms via artificial induction in laboratory conditions is possible and may be useful for the application of the microorganisms for the bioremediation of heavy metals.

• 미생물학회지
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• 제8권2호
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• pp.53-64
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• 1970

In order to study ecology of microorganisms during Takju brewing, microflora changes were examined fromm the start to the sixth day of Takju fermentation in 24 hours intervals. Takju made from rice, flour and dried sweet potato in a liter volume open container at the laboratory and a sanple of Takju brewing factory were studied for their microflora and their changes during fermentationl together with a sample of Kokja. Results obtained were as follows ; 1. The followings were the identified microorganisms in Kokja. The molds ; Absidia spinosa, Aspergillus parasiticus. The yeasts ; Candida melinii, Candida Solani, Hansenula anomala. The bacteria ; Luctobacillus casei, Leuconostoc mesenteroides, Bacillus subtilis, Bacillus pumilus. 2. Torulopsis inconspicua, Lactobacillus casei, Leuconotoc mesenteroides, Bacillus subtilis, Bacillus pumilus were isolated from main mash of laboratory-made Takju samples. The yeast, Torupsis inconspicua which was not present in Kokja and, probably of a contaminant yeast, dominated the yeast flora of Takju mash of rice, flour and sweet potato of labotatory brewing. The laboratory brewing lost also always showed large population of lactic acid bacteria flora. 3. None of the wild yeasts which were present in Kokja appeared in Takju mashes. The Kokja appears to be of no use as the yeast source for Takju fermentation. Also the Kokja appears to be of not so effective amylolytic and proteolytic enzyme sources considering the microflora characteristics. Probably the major role of Kokja in Takju fermentation may be to contribute in taste formation. 4. Inoculation of Sacharomyces cerevisiae into the mash to the level of $10^7$ ml at the start of fermentation greatly changed the ecological aspects eliminating conditions of rather slow rising of natural contaminant yeast populaiton and fermentation which might give rise to prosperity of lactic acid and Bacillus bacteria that would be avoidable. 5. Examination of microflora of the large factory scale Takju fermentation showed the quite similar pattern of microflora and their changes to that of the cultured yeast-inoculated laboratory batch Takju fermentation. The cultured yeast dominated as the only predominant microflora, and the lactic acid bacteria flora were completely suppressed and aerobic bacteria, greatly. Probably this may be the regular microflora pattern of normal Takju fermentation. The role of lactic acid bacteria and aerobic bacteria in Takju fermentation may not be clear yet from this experiment alone.

• 한국자원식물학회지
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• 제21권5호
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• pp.352-356
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• 2008

본 연구는 천연 식품보존료 개발의 일환으로 식품에 널리 이용되고 있는 오레가노를 에탄올로 추출하여 식중독에 관련이 있는 세균에 대해 농도 의존적으로 항균효과를 보였으며, 그 중에서 Salmonella enteritdis균에 대해 가장 높은 항균효과를 보였다. 또 오레가노 에탄올 추출물이 식중독 유발세균의 성장에 미치는 효과를 검정하기 위해 Salmonella typhimurium, Listeria monocytogenes의 배양액에 오레가노 에탄올 추출물을 각 농도별로 첨가하여 생육을 조사한 결과, Salmonella typhimurim와 Listeria monocytogenes 생육은 오레가노 에탄올 추출물 $700 mg{\cdot}L^{-1}$ 농도에서 각각 60시간 및 36시간까지 억제됨을 관찰할 수 있었다. 본 연구결과는 오레가노 에탄올 추출물이 식중독을 유발시키는 세균에 대하여 우수한 항균작용을 나타내고 있으며, 따라서 오레가노가 효과적인 천연보존료로서 이용될 수 있음을 시사하고 있다.

• Journal of Microbiology and Biotechnology
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• 제31권12호
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• pp.1656-1666
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• 2021

Dental pathogens lead to chronic diseases like periodontitis, which causes loss of teeth. Here, we examined the plausible antibacterial efficacy of copper nanoparticles (CuNPs) synthesized using Cupressus macrocarpa extract (CME) against periodontitis-causing bacteria. The antimicrobial properties of CME-CuNPs were then assessed against oral microbes (M. luteus. B. subtilis, P. aerioginosa) that cause periodontal disease and were identified using morphological/ biochemical analysis, and 16S-rRNA techniques. The CME-CuNPs were characterized, and accordingly, the peak found at 577 nm using UV-Vis spectrometer showed the formation of stable CME-CuNPs. Also, the results revealed the formation of spherical and oblong monodispersed CME-CuNPs with sizes ranged from 11.3 to 22.4 nm. The FTIR analysis suggested that the CME contains reducing agents that consequently had a role in Cu reduction and CME-CuNP formation. Furthermore, the CME-CuNPs exhibited potent antimicrobial efficacy against different isolates which was superior to the reported values in literature. The antibacterial efficacy of CME-CuNPs on oral bacteria was compared to the synergistic solution of clindamycin with CME-CuNPs. The solution exhibited a superior capacity to prevent bacterial growth. Minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and fractional inhibitory concentration (FIC) of CME-CuNPs with clindamycin recorded against the selected periodontal disease-causing microorganisms were observed between the range of 2.6-3.6 ㎍/ml, 4-5 ㎍/ml and 0.312-0.5, respectively. Finally, the synergistic antimicrobial efficacy exhibited by CME-CuNPs with clindamycin against the tested strains could be useful for the future development of more effective treatments to control dental diseases.