• 자원환경지질
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• 제43권3호
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• pp.223-233
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• 2010

세포외 중합체(EPS)의 존재 유무에 따라 Pseudomonas aeruginosa가 용존 비소, 크롬, 우라늄의 흡착 및 산화상태의 변화에 미치는 영향을 회분식 실험을 통해 조사하였다. 배양한 미생물의 표면을 세척한 것과 세척하지 않은 것으로 구분하여 무영양 상태에서 1.1 mg/L의 As(V)와 Cr(VI), 0.5 mg/L의 U(VI)와 반응시키며 시간에 따라 각각의 총 용존 함량과 산화상태 변화를 측정하였다. As(V)의 경우 EPS 존재 여부와 관계없이 흡착은 발생하지 않았으나 EPS가 보존된 박테리아는 As(V)의 약 60%를 As(III)로 환원하였다. 표면을 세척하지 않은 박테리아는 총 용존 크롬의 45%를 제거하였으며 잔류된 용존 크롬의 64%를 Cr(III)로 환원하였다. 우라늄의 경우, 박테리아 표면을 세척하지 않았을 때 U(VI)의 약 80% 이상이 용액으로부터 제거되었다. 이러한 원소 환원은 박테리아가 분비한 EPS 자체의 환원 능력 또는 EPS로부터 보호받아 생육성이 보존된 박테리아의 해독성 환원에 의한 것으로 여겨진다. 이 연구 결과는 자연 환경에서 대부분 바이오필름 상태로 존재하는 미생물이 비소, 크롬, 우라늄의 산화상태 및 이동도 조절에 지대한 영향을 미칠 수도 있음을 의미한다.

• Journal of Microbiology
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• 제41권3호
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• pp.183-188
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• 2003

We isolated and cultured bacteria that inhabited marine biofilms, and identified them by phylogenetic analysis using 16S rDNA sequences. In the marine environment, biofilms cover most subtidal and intertidal solid surfaces such as rocks, ships, loops, marine animals, and algae. The bacteria in most biofilms are embedded in extracellular polymeric substances that comprise mainly of exopolysaccharides. The exopolysaccharides are excreted from multiple bacterial species; therefore, biofilms are a good source for screening exopolysaccharide-producing bacteria. Thirty-one strains were cultured, and a total of 17 unique strains were identified. Phylogenetic analysis using 16S rDNA sequences indicated that the 17 strains belonged to ${\alpha}$-Proteobacteria (Ochrobactrum anthropi, Paracoccus carotinifaciens); ${\gamma}$-Proteobacteria (Pseudoalteromonas agarovorans, P. piscicida, Pseudomonas aeruginosa, Shewanella baltica, Vibrio parahaemolyticus, V. pomeroyi); CFB group bacteria (Cytophaga latercula, Tenacibaculum mesophilum); high GC, Gram-positive bacteria (Arthrobacter nicotianae, Brevibacterium casei, B. epidermidis, Tsukamurella inchonensis); and low GC, Gram-positive bacteria (Bacillus macroides, Staphylococcus haemolyticus, S. warneri).

• Journal of Microbiology and Biotechnology
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• 제17권1호
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• pp.110-115
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• 2007

Electrochemically active bacteria were successfully enriched in an electrochemical cell using a positively poised working electrode. The positively poised working electrode (+0.7 V vs. Ag/AgCl) was used as an electron acceptor for enrichment and growth of electrochemically active bacteria. When activated sludge and synthetic wastewater were fed to the electrochemical cell, a gradual increase in amperometric current was observed. After a period of time in which the amperometric current was stabilized (generally 8 days), linear correlations between the amperometric signals from the electrochemical cell and added BOD (biochemical oxygen demand) concentrations were established. Cyclic voltammetry of the enriched electrode also showed prominent electrochemical activity. When the enriched electrodes were examined with electron microscopy and confocal scanning laser microscopy, a biofilm on the enriched electrode surface and bacterium-like particles were observed. These experimental results indicate that the electrochemical system in this study is a useful tool for the enrichment of an electrochemically active bacterial consortium and could be used as a novel microbial biosensor.

• 환경생물
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• 제21권4호
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• pp.358-365
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• 2003

A bacterial strain capable of producing a novel bioflocculant was isolated from a biofilm sample and identified as Bacillus megaterium G31. The highest biopolymer yield was achieved when the organism was cultivated in a medium containing acetate as the sole carbon source and ($NH_4)_2HPO_4$as the nitrogen source. In kaolin suspension, the flocculating activity was highest at 170 mg I$^{-1}$ and decreased at the higher bioflocculant concentrations. The crude bioflocculant produced by the organism was purified by ethanol precipitation and gel permeation chromatography. The FTIR spectrum of the purified bioflocculant revealed that the bioflocculant might be a heterogeneous polysaccharide composed of hexosamines and neutral sugars. The analysis of sugar components of the bioflocculant using high performance anion-exchange chromatography showed that the sugar constituents of the bioflocculant were glucosamine, fucose, galactosamine, galactose, glucose, mannose in approximate molar ratio of 4 : 1 : 6 : 3 : 8 : 19. Its flocculating activity was stimulated by various cations. The bioflocculant was thermo-stable and retained 64% of its original activity after heating at $100^{\circ}C$ for 50 min.

• Journal of Microbiology and Biotechnology
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• 제21권3호
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• pp.243-251
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• 2011

The gene bolA was discovered in the 80's, but unraveling its function in the cell has proven to be a complex task. The BolA protein has pleiotropic effects over cell physiology, altering growth and morphology, inducing biofilm formation, and regulating the balance of several membrane proteins. Recently, BolA was shown to be a transcription factor by repressing the expression of the mreB gene. The present report shows that BolA is a transcriptional regulator of the dacA and dacC genes, thus regulating both DD-carboxypeptidases PBP5 and PBP6 and thereby demonstrating the versatility of BolA as a cellular regulator. In this work, we also demonstrate that reduction of cell growth and survival can be connected to the overexpression of the bolA gene in different E. coli backgrounds, particularly in the exponential growth phase. The most interesting finding is that overproduction of BolA affects bacterial growth differently depending on whether the cells were inoculated directly from a plate culture or from an overnight batch culture. This strengthens the idea that BolA can be engaged in the coordination of genes that adapt the cell physiology in order to enhance cell adaptation and survival under stress conditions.

• Membrane and Water Treatment
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• 제6권3호
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• pp.189-203
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• 2015

Membrane biofouling impedes wide application of membrane bioreactor (MBR) for wastewater treatment. Recently, quorum sensing (QS) mechanisms are accounted for one of major mechanisms in biofouling of MBRs. In this study, vanillin was applied to investigate reduction of biofouling in MBRs. MBR sludge was analyzed to contain QS signal molecules by cross-feeding biosensor assay and HPLC. In addition, the inhibitory activity of vanillin against bacterial quorum sensing was verified using an indicator strain CV026. The vanillin doses greater than 125 mg/L to 100 mL of MBR sludge showed 25% reduction of biofilm formed on the membrane surfaces. Two MBRs, i.e., a typical MBR as a control and an MBR with vanillin, were operated. The TMP increases of the control MBR were more rapid compared to those of the MBR with the vanillin dose of 250 mg/L. The treatment efficiencies of the two MBRs on organic removal and MLSS were maintained relatively constant. Extracellular polymeric substance concentrations measured at the end of the MBR operation were 173 mg/g biocake for the control MBR and 119 mg/g biocake for the MBR with vanillin. Vanillin shows great potential as an anti-biofouling agent for MBRs without any interference on microbial activity for wastewater treatment.

• Journal of Ginseng Research
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• 제44권2호
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• pp.194-204
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• 2020

The detrimental impact of air pollution as a result of frequent exposure to fine particles posed a global public health risk mainly to the pulmonary disorders in pediatric and geriatric population. Here, we reviewed the current literature regarding the role of ginseng and/or its components as antimicrobials, especially against pathogens that cause respiratory infections in animal and in vitro models. Some of the possible mechanisms for ginseng-mediated viral inhibition suggested are improvements in systemic and mucosa-specific antibody responses, serum hemagglutinin inhibition, lymphocyte proliferation, cell survival rate, and viral clearance in the lungs. In addition, ginseng reduces the expression levels of proinflammatory cytokines (IFN-γ, TNF-α, IL-2, IL-4, IL-5, IL-6, IL-8) and chemokines produced by airway epithelial cells and macrophages, thus preventing weight loss. In case of bacterial infections, ginseng acts by alleviating inflammatory cytokine production, increasing survival rates, and activating phagocytes and natural killer cells. In addition, ginseng inhibits biofilm formation and induces the dispersion and dissolution of mature biofilms. Most clinical trials revealed that ginseng, at various dosages, is a safe and effective method of seasonal prophylaxis, relieving the symptoms and reducing the risk and duration of colds and flu. Taken together, these findings support the efficacy of ginseng as a therapeutic and prophylactic agent for respiratory infections.

• Journal of Microbiology and Biotechnology
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• 제32권1호
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• pp.56-63
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• 2022

This study aims to determine the antibiofilm effect of cell-free supernatant (CFS) of Lactobacillus brevis strains against Streptococcus mutans strains. To study the antibiofilm mechanism against S. mutans strains, antibacterial effects, cell surface properties (auto-aggregation and cell surface hydrophobicity), exopolysaccharide (EPS) production, and morphological changes were examined. The antibiofilm effect of L. brevis KCCM 202399 CFS as morphological changes were evaluated by scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM), compared with the control treatment. Among the L. brevis strains, L. brevis KCCM 202399 showed the highest antibiofilm effect on S. mutans KCTC 5458. The antibacterial effect of L. brevis KCCM 202399 against S. mutans KCTC 5458 was investigated using the deferred method (16.00 mm). The minimum inhibitory concentration of L. brevis KCCM 202399 against S. mutans KCTC 5458 was 25.00%. Compared with the control treatment, L. brevis KCCM 202399 CFS inhibited the bacterial adhesion of S. mutans KCTC 5458 by decreasing auto-aggregation, cell surface hydrophobicity, and EPS production (45.91%, 40.51%, and 67.44%, respectively). L. brevis KCCM 202399 CFS inhibited and eradicated the S. mutans KCTC 5458 biofilm. Therefore, these results suggest that L. brevis KCCM 202399 CFS may be used to develop oral health in the probiotic industry.

• Restorative Dentistry and Endodontics
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• 제47권1호
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• pp.11.1-11.11
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• 2022

This study aimed to describe the outcomes of the GentleWave system (GW) (Sonendo) on root canal treatment. Published articles were collected from scientific databases (MEDLINE/PubMed platform, Web of Science, Scopus, Science Direct and Embase). A total of 24 studies were collected from August/2014 to July/2021, 20 in vitro and 4 clinical. GW System was not associated with extrusion of the irrigant, promoted faster organic dissolution than conventional syringe irrigation (CSI), passive ultrasonic irrigation (PUI) continuous ultrasonic irrigation (CUI) and EndoVac, reduced more bacterial DNA and biofilm than PUI and CUI, promoted higher penetration of sodium hypochlorite into dentinal tubules than PUI and CUI in vitro, and removed more intracanal medication than CSI and PUI. GW was able to remove pulp tissue and calcifications. Moreover, its ability to remove hard-tissue debris and smear layer was better than that of CSI, and its ability to remove root canal obturation residues was lower or similar to that of PUI, and similar to that of CSI and EndoVac. Regarding root canal obturation of minimally instrumented molar canals, GW was associated with high-quality obturation. Clinically, the success rate of endodontic treatment using GW was 97.3%, and the short-term postoperative pain in the GW group was not different from CSI. Further research, mainly clinical, is needed to establish whether GW has any advantages over other available irrigation methods.

• 미생물학회지
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• 제52권4호
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• pp.428-436
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• 2016

항균제에 대한 내성 증가는 국내뿐만 아니라 세계적으로도 인류 건강에 큰논란이 되고 있다. 박테리아에 의한 감염을 치료하기 위해 같은 혹은 다른 계열의 항생제에 순차적으로 노출된다. 따라서, 본 연구는 ciprofloxacin과 meropenem의 순차적 처리에 따른 폐렴간균(Klebsiella pneumoniae)의 생육, 항생제 민감성, 돌연변이 빈도, ${\beta}$-lactamase activity, 생물막 형성 및 내성 관련 유전자 발현을 평가하기 위해 설계되었다. 처리군은 대조군(control; CON), 1/2 MIC ciprofloxacin (1/2CIP), 2 MIC ciprofloxacin (2CIP), 1/2 MIC ciprofloxacin+1/2 MIC meropenem+2 MIC ciprofloxacin (1/2CIP-1/2MEM-2CIP), 1/2 MIC ciprofloxacin+1/2 MIC meropenem+2 MIC meropenem(1/2CIP-1/2MEM-2MEM), 1/2 MIC ciprofloxacin+2 MIC ciprofloxacin+2 MIC meropenem (1/2CIP-2CIP-2MEM)을 포함한다. 24시간의 배양 동안 2CIP처리군에서 K. pneumoniae의 생육이 관찰되지 않았다. 모든 처리군에서 planktonic cell의 수는 7에서 10 log CFU/ml의 유의적인 차이를 보였으나 biofilm cell의 수는 7 log CFU/ml로 비슷하였다. 돌연변이 빈도는 1/2CIP-1/2MEM-2CIP에서 가장 낮은 14%을 보였다. 대조군과 비교하여 1/2CIP-2CIP-2MEM 처리 K. pneumoniae는 piperacillin, cefotaxime, nalidixic에 대한 민감도가 감소되었다. 1/2CIP-1/2MEM-2CIPrk 가장 높은 ${\beta}$-lactamase activity(22 nmol/min/ml)을 보인 반면 1/2CIP-2CIP-2MEM은 가장 낮은 ${\beta}$-lactamase activity (6 nmol/min/ml)을 보였다. Multidrug efflux pump 관련 유전자(acrA, acrB, and ramA)의 발현은 1/2CIP-1/2MER-2MER and 1/2CIP2CIP-2MER 처리된 K. pneumoniae에서 2배 이상 증가하였다. 따라서 순차적 항생제의 처리는 K. pneumoniae의 항생제 내성 양상을 변화시킬 수 있다.