• Journal of Dairy Science and Biotechnology
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• 제39권4호
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• pp.145-156
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• 2021

Antibiotics are used in many sectors, including the dairy industry, to prevent bacterial infections in humans, animals, and plants. When bacterial cells are exposed to stressors, such as antibiotic exposure, a subpopulation of the cells becomes dormant. This helps the pathogen to revive and reconstitute its pathogenicity. Thus, eradicating the dormant cells may be an effective strategy to reduce the development of antibiotic resistance in bacteria caused by the abuse of antibiotics. In recent years, a large number of indole-related compounds have been reported to eradicate persister cells. In this review, we provide a summary of the mechanisms of persister cell formation and resuscitation, and the ability of indole and substituted indoles to eradicate persister cells.

• 대한기관식도과학회:학술대회논문집
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• 대한기관식도과학회 1993년도 제27차 학술대회 초록집
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• pp.98-98
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• 1993

편도선의 염증반응은 세균이 편도상피세포에 부착되는 것으로부터 시작되며 부착된 세균은 증식하여 집락을 형성한 후 독소를 분비하여 점막 장벽을 뚫고 조직에 손상을 일으킨다. 저자들은 급성편도선염의 병태를 이해하기 위하여 생체내에서 급성편도선염 환자군과 정상인에서 상피세포의 세균부착성에 대한 차이를 알아보고자 본 실험을 시행하였다. 급욍편도선염 환자군 20례와 정상인 대조군 20례를 대상으로 편도선부위를 면봉으로 문지른후 세포혼합물을 Acridine orange로 염색하여 형광현미경하에서 관찰하였다. 50개의 편도상피세포에서 부착된 세균수를 계산하였다. 또한 동시에 근배양을 시행하였다. 급성편도선염군은 대조군보다 상피세포에서 10% 이상 부착된 세균수가 많았으며 (p<0.05), 상피세포에 부착된 세균수는 연령과 유의한 상관관계를 보여주었다.

• Journal of Microbiology and Biotechnology
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• 제18권9호
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• pp.1518-1521
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• 2008

Bacteria sense their population density and coordinate the expression of target genes, including virulence factors in Gram-negative bacteria, by the N-acylhomoserine lactones (AHLs)-dependent quorum sensing (QS) mechanism. In contrast, several soil bacteria are able to interfere with QS by enzymatic degradation of AHLs, referred to as quorum quenching. A potent AHL-degrading enzyme, AiiA, from Bacillus thuringiensis has been reported to effectively attenuate the virulence of bacteria by quorum quenching. However, little is known about the role of AiiA in B. thuringiensis itself. In the present study, an aiiA-defective mutant was generated to investigate the role of AHA in rhizosphere competence in the root system of pepper. The aiiA mutant showed no detectable AHL￢-egrading activity and was less effective for suppression of soft-rot symptom caused by Erwinia carotovora on the potato slice. On the pepper root, the survival rate of the aiiA mutant significantly decreased over time compared with that of wild type. Interestingly, viable cell count analysis revealed that the bacterial number and composition of E. carotovora were not different between treatments of wild type and the aiiA mutant. These results provide evidence that AHA can play an important role in rhizosphere competentce of B. thuringiensis and bacterial quorum quenching to Gram-negative bacteria without changing bacterial number or composition.

• KSBB Journal
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• 제13권6호
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• pp.644-648
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• 1998

In the production of a low cost bacterial insecticide, it is important to produce a high spore concentration using low price substrates. Experiments were carried out to investigate the effects of the addition of mineral salts and glucose, and of dissolved oxygen concentration on the cell growth and spore formation of Bacillus thuringiensis var aizawai using a cheap wheat and soybean meal in the batch culture. The maximum viable cell number was 1.2${\times}$109 CFU/mL at 12 hr culture and spore yield was 54.2% at 74 hr culture using an industrial medium containing 20 g/L wheat meal and 30 g/L soybean meal under 1.0 vvm aeration and 200 rpm agitation. The cell growth and the spore formation were not enhanced by the addition of mineral salts in industrial medium, whereas th addition of 10g/L glucose decreased the cell growth and spore formation. We could obtain a maximum viable cell number of 2.2${\times}$109 CFU/mL and spore number of 1.9${\times}$109 CFU/mL at the dissolved oxygen concentration of 60% of saturation. The spore concentration was enhanced approximately by 2 times as compared to the dissolved oxygen concentration of 50%. In the bench-scale culture, the maximum viable cell and spore number were 2.5${\times}$109 CFU/mL, and 2.2${\times}$109 CFU/mL, respectively under 1.0 vvm aeration and 400 rpm agitation. The spore yield was 88% based on the maximum viable cell number. As a result, it was confirmed that the production of high spore concentration could be obtained by a bench-scale culture using an industrial medium.

• The Plant Pathology Journal
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• 제23권3호
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• pp.203-209
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• 2007

Infection structures were observed using a fluorescence microscope at the penetration sites on the leaves of potato plants pre-inoculated with the bacterial strains Pseudomonas putida TRL2-3, Micrococcus luteus TRK2-2, and Flexibacteraceae bacterium MRL412, which mediated an induced systemic resistance on potato plants against late blight disease caused by Phytophthora infestans. In order to compare the infection structures on the leaves expressing systemic acquired resistance, the leaves of potato plants pre-treated with DL-3-amino butyric acid (BABA) were also observed after challenge inoculation with the same pathogen. The infection structures were investigated. The total number of germination and appressorium formation of P. infestans were counted. Furthermore, the frequencies of fluorescent epidermal cells at the penetration sites, which indicate a defense response of plant cell, were estimated. There were no differences on the germination rates of the fungal cysts among the untreated control, BABA pre-treated, and bacterial strains pre-inoculated plants. However, appressorium formation was slightly decreased on the leaves of BABA pre-treated plants compared to those of untreated as well as bacterial strains pre-inoculated plants. Furthermore, the frequencies of fluorescent cells of BABA pre-treated and bacterial strains pre-inoculated were higher than that of untreated plants, indicating an active defense reaction of the host cells against the fungal attack. On the other hand, the pre-treatment with BABA caused a stronger fluorescent of epidermal cells at the penetration sites compared to the pre-inoculation with the bacterial strains. Interestingly, the frequency of fluorescent cells by BABA, however, was lower than that by the bacterial strains. Based on the results it is suggested that the infection structures showing resistance reaction on the leaves of potato plants were different between by pre-inoculation with bacterial strains and by pre-treatment with BABA against the late blight pathogen.

• 미생물학회지
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• 제45권2호
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• pp.148-154
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• 2009

퇴비화 과정은 유기성 폐기물을 비료와 같은 유용한 자원으로 전환하는 생물학적 과정이다. 본 연구에서는 음식 물 쓰레기를 2달 동안 퇴비화시켜 세균군집의 변화를 조사하였다. 온도의 변화를 기준으로 하여 퇴비화 과정은 1단계($2\sim55^{\circ}C$), 2단계($55\sim97^{\circ}C$), 3단계($50\sim89^{\circ}C$)로 나뉘었다. 각 단계별 총세균수는 1단계 $1.66\times10^{11}$ cell/g, 2단계 $0.29\times10^{11}$ cell/g, 3단계 $0.28\times10^{11}$ cell/g으로 관찰되었다. 또한 총세균수에 대한 고온미생물의 비율은 초기에 33% 였으나 2단계 시료에서 최대비율인 89%로 증가하였다. 16S rRNA 유전자를 대상으로 T-RFLP 방법과 염기서열 분석방법을 이용하여 세균군집의 구조가 퇴비화 과정에 따라 변화됨을 확인할 수 있었다. 초고온인 2단계의 세균군집의 발달은 스타터 접종의 영향을 받았으며, Bacillus 및 Pseudomonas와 유연관계가 가까운 세균군집이 퇴비화 과정을 이끄는 주요 미생물임을 확인하였다.

• Journal of Microbiology
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• 제37권1호
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• pp.1-9
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• 1999

The Biolog redox technology was carried out for evaluation of acidification effect on microbial communities at each stage of pH gradient microcosm. While the number of heterotrophic bacterial population and activities of extracellular enzyme decreased as the pH decreased, the number of total bacteria in the microcosm was not affected. The average color development of sample at each pH-gradient showed a sigmoidal curve, and at higher pH, more overall color development appeared in Biolog plates. Average color development value in Biolog plates was stabilized at 50 hours as an optimum incubation time. The color production in the Biolog plates was caused by cell density at above pH 5.0, but by cell activity below pH 4.0. Principal component analysis of color responses revealed distinctive patterns among the pH-gradient microcosm samples.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2001년도 추계학술발표대회
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• pp.918-922
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• 2001

In a previous study, we have isolated a number of lactobacilli from Korean women, and one of them (KLB46) was identified as Lactobacillus crispatus by 16S rRNA gene sequencing. For the ecological treatment of bacterial vaginosis (BV) cell suspension of L. crispatus KLB46 was instillated into BV patients. L. crispatus KLB46 was found to persist for several days in cell suspension with no nutrients. In this study, in order to assess the influence of starvation on physiological activity, we compared the viability and culturability of KLB46 following suspension in various buffer solutions. A pair of in situ fluorescent dye was used to assess viability (i.e. membrane integrity) and the culturability was examined by plate count assay. A rapid epifluorescence staining method using the LIVE/DEAD Bacterial Viability Kit $(BacLight^{TM})$ was applied to estimate both viable and total counts of bacteria in cell suspension. $BacLight^{TM}$ is composed of two nucleic acid-binding stains ($SYTO\;9^{TM}$ and propidium iodide). $SYTO\;9^{TM}$ penetrates all bacterial membranes and stains the cells green while propidium iodide only penetrates cells with damaged membranes, therefore the combination of the two stains produces red fluorescing cells. Optimal staining conditions for $BacLight^{TM}$ were found to be with 0.0835M $SYTO\;9^{TM}$ and 0.05M propidium iodide for 15 min incubation at room temperature in dark. When cells were microscopically examined during 140 hours of starvation, the culturability decreased markedly while the viability remained relatively constant, which suggests that large fraction of KLB46 cells became viable but non-culturable (VBNC) upon starvation.

• 미생물학회지
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• 제50권1호
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• pp.84-86
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• 2014

길항균을 생물 농약으로 개발하기 위해서는 저렴한 산업용 배지를 이용한 대량 생산 체계를 확립하는 것이 중요하다. 본 연구에서는 풋마름병 방제 효과가 뛰어난 Bacillus amyloliquefaciens SKU-78 균주의 배양조건을 확립하였다. 저가의 산업용 기질로는 콩가루와 옥수수 전분 배지가 균 생장에 가장 효과적이었고, 최초 pH 5.5, 배양 온도 $30^{\circ}C$, 교반속도 150-250 rpm의 조건으로 30 L fermenter를 이용한 배양에서 20 시간째에 최대 생균수($1.2{\times}10^{11}$ CFU/ml)에 도달하였다. 저가의 산업용 배지로 배양한 배양액을 관주 처리하였을 때 65%의 발병 억제 효과를 나타냄으로써 SKU-78 균주의 산업용 배지를 이용한 대량배양의 기초가 마련되었다.

• 대한한의학회지
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• 제27권3호
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• pp.51-62
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• 2006

Objective: Although chronic non-bacterial prostatitis is a common disease, it is very difficult to treat effectively. Lygodium japonicum has traditionally been used in treatment of urinary tract inflammation and voiding disturbance. In this study, we investigated the therapeutic effects and action mechanism of Lygodium japonicum in the rat model of non-bacterial prostatitis induced by castration and testosterone treatment. Methods: Five-month-old rats were treated with $17\beta-estradiol$ after castration for induction of experimental non-bacterial prostatitis, which is similar to human chronic prostatitis in histopathological profiles. Lygodium japonicum and testosterone were administered as an experimental specimen and a positive control, respectively. The prostates were evaluated by histopathological parameters including the epithelial score and epithelio-stromal ratio for glandular damage, proliferating cell nuclear antigen (PCNA) labeling index for cyto-proliferation and a TUNEL (deoxyuridine triphosphate biotin nick end-labeling) assay for cell apoptosis. Results: While prostates of control rats revealed severe acinar gland atrophy and stromal proliferation, the rats treated with Lygodium japonicum showed a lesser range of tissue damage. Epithelial score was improved in Lygodium japonicum than that of the control (P<0.05). The epithelio-stromal ratio was lower in Lygodium japonicum when compared to that of the control (P<0.05). Although there was no difference in PCNA and TUNEL positive cells of the glandular epithelia, we found an decreased number of PCNA positive cell and concurrent increase of TUNEL positive cells in the stroma of Lygodium japonicum treated rats (P<0.01). Conclusions: These findings suggest that Lygodium japonicum may protect the glandular epithelial cells and also inhibit stromal proliferation in association with suppression of cyto-proliferation and stimulation of apoptosis. We concluded that Lygodium japonicum may be a useful remedy agent for treating the chronic non-bacterial prostatitis.