• Toxicological Research
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• 제29권2호
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• pp.129-135
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• 2013

Salmonella is one of the major pathogenic bacteria that cause food poisoning. This study investigated whether heat-killed as well as live Lactobacillus protects host animal against Salmonella infection. Live and heat-killed Lactobacillusacidophilus was administered orally to Sprague-Dawley rats for 2 weeks before the rats were inoculated with Salmonella. Rise in body temperature was moderate in the group that was treated with heat-killed bacteria as compared to the Salmonella control group. The mean amount of feed intake and water consumption of each rat in the heat-killed bacteria group were nearly normal. The number of fecal Salmonellae was comparable between the live and the heat-killed L. acidophilus groups. This finding shows that L. acidophilus facilitates the excretion of Salmonella. Moreover, the levels of pro inflammatory cytokines, including tumor necrosis factor (TNF)-alpha and interleukin (IL)-1 beta, in the heat-killed L. acidophilus group were significantly lower when compared to the levels in the Salmonella control group. These results indicate that nonviable lactic acid bacteria also could play an important role in preventing infections by enteric pathogens such as Salmonella.

• 미생물학회지
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• 제40권4호
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• pp.364-366
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• 2004

본 연구는 차 카테킨인 EGCG (epigallocatechin gallate)에 의한 구강세균의 살균효과를 조사하기 위하여 수행되었다. 초기 세포밀도 $10^{7}$ cell/ml의 대상 세균에 대한 항세균 활성은 EGCG 1ml당 5mg에서 조사하였다. 선택 또는 복합배지상에서 집락생성단위(colony-forming unit, CFU)에 근거하여 EGCG의 항세균 활성은 농도에 비례하는 것을 확인하였다. Streptococcus mutans와 Streptococcus sobrinus는 5mg/ml의 EGCG에서 8시간 이내에 완전히 살균되었다. Lactobacillus acidophilus와 Lactobacillus plantarum도 동일한 조건에서 각각 2시간과 4시간 이내에 살균되었다. 2.5 mg/ml의 EGCG로 처리한 사람의 타액에서 유래하는 총 구강세균의 생존율을 BHI 고체배지상에서 조사하였으며, 총 구강세균은 10시간 이내에 완전히 살균되었다. MS 고체배지상에서 S. mitis and S. salivarius의 집락은 감소되었으며 배양 12시간 이내에서는 집락은 관찰되지 않았다. 그 결과, EGCG는 입냄새와 치석의 원인이 되는 구강세균을 살균시키고 충치를 예방하는 자연적이며 효과적인 물질임이 입증되었다.

• Restorative Dentistry and Endodontics
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• 제25권4호
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• pp.606-618
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• 2000

Dental pulp infection is most commonly caused by extensive dental caries, and some bacterial species invade root canals; bacterial components and products are thought to be associated with the pathogenesis of periapical periodontitis. A principle driving force behind pulpal disease response appears to lie in the host immune system's to bacteria and their products. We examined the production of interleukin $1{\beta}$ (IL-$1{\beta}$) and tumor necrosis factor ${\alpha}$(TNF-${\alpha}$) from human peripheral mononuclear cells, lymphocytes and monocytes stimulated by heat-killed Acitnobacillus actinomycetemcomitans (ATCC 29523), Porphyromonas gingivalis (ATCC 33277) and Prevotella intermedia (ATCC 25611), and also by their sonicated bacterial extracts (SBE), respectively. The effects of three strains of heat-killed bacteria and their SBEs on the morphology of cultured blood cell lines HL-60 (KCLB 10240) and J774A.1 (KCLB 40067) were observed under the inverted microscope. Ultrastructural changes of J774A.1 exposed to heat-killed P. intermedia and its SBE were investigated using transmission electron microscopy. Production of IL-$1{\beta}$ was reduced in human peripheral mononuclear cells after stimulation by sonic bacterial extracts of A. actinomycetemcomitans, P. gingivalis, and P. intermedia. Heat-killed and sonic extract of P. gingivalis inhibited the production of TNF-${\alpha}$ in peripheral mononuclear cells. Production of TNF-${\alpha}$ was inhibited in peripheral monocytes after stimulation by sonic extracts of A. actinomycetemcomitans, P. gingivalis, and P. intermedia. HL-60 and J 774A.1 cells showed granular degeneration after treatment with heat-killed and sonic extracts of A. actinomycetemcomitans, P. gingivalis, and P. intermedia Chromatin margination and shrinkage were observed in 774A.1 treated with heat-killed P. intermedia. Cell wall structure and organelles were destroyed and vacuoles were formed in cytoplasm in J774A.1 treated with P. intermedia sonic extract. These results suggest that A actinomycetemcomitans, P gingivalis and P intermedia may have an important role in the formation and progression of pulpal diseases via both modulation of production of IL-$1{\beta}$ and TNF-${\alpha}$ from blood mononuclear cells and cytopathic effects.

• Journal of Microbiology and Biotechnology
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• 제16권5호
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• pp.661-666
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• 2006

The present study represents the investigation of in vitro immunopotentiating activities of cellular fractions of major lactic acid bacteria found in kimchi (KLAB) and bifidobacteria. The macrophage cells, RAW264.7, were stimulated with heat-killed whole-cell, cell-wall, and cytoplasmic fractions of four strains of KLAB (Leuconostoc mesenteroides, Leuconostoc citreum, Lactobacillus plantarum, and Lactobacillus sake) and two strains of bifidobacteria (Bifidobacterium longum and Bifidobacterium lactis) each, and then the production of nitric oxide (NO) and cytokines including tumor necrosis $factor-\alpha\;(TNF-\alpha)$ and interleukin-6 (IL-6) was measured by Griess and ELISA assays, respectively. Heat-killed wholecell and cell-wall fractions-but not the cytoplasmic fraction-from all strains of KLAB significantly increased the production of NO in RAW264.7 cells, and all fractions from bifidobacteria exerted similar effects. In the production of $TNF-\alpha$, heat-killed whole-cell and cell-wall fractions of L. plantarum showed the strongest effect, followed by L. sake and B. lactis, whereas other KLAB fractions did not exert any effect. In the production of IL-6, only whole-cell and cell-wall fractions of L. plantarum were effective. These results, taken together, indicate that L. plantarum might playa critical role in the immunopotentiating activities of kimchi.

• Journal of Microbiology and Biotechnology
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• 제33권9호
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• pp.1189-1196
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• 2023

This study proposed to demonstrate the neuroprotective effects of heat-killed Levilactobacillus brevis KU15152. Heat-killed L. brevis KU15152 showed antioxidant activity similar to that of Lacticaseibacillus rhamnosus GG, in terms of radical scavenging activity. To evaluate the neuroprotective effects, conditioned medium (CM) obtained by incubating heat-killed bacteria in intestinal cells (HT-29) was used through gut-brain axis. CM from L. brevis KU15152 protected neuroblastoma cells (SH-SY5Y) against H₂O₂-induced oxidative stress. Pretreatment with CM significantly alleviated the morphological changes induced by H₂O₂. Heat-killed L. brevis KU15152 showed an increased brain-derived neurotrophic factor (BDNF) expression in HT-29 cells. L. brevis KU15152-CM remarkably downregulated the Bax/Bcl-2 ratio, while upregulating the expression of BDNF and tyrosine hydroxylase (TH) in SH-SY5Y cells. Furthermore, L. brevis KU15152-CM reduced caspase-3 activity following H₂O₂ treatment. In conclusion, L. brevis KU15152 can be potentially used as food materials to avoid neurodegenerative diseases.

• 미생물학회지
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• 제51권3호
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• pp.241-248
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• 2015

프로바이오틱스에 대한 연구는 주로 생균의 효과가 많이 알려져 있지만 가열 처리된 유산균인 사균체의 기능에 대한 연구도 활발히 이루어지고 있다. 본 연구에서는 락토바실러스 아시도필러스 CBT LA1의 사균체의 장관장벽 기능에 대하여 in vitro, in vivo에서 실험하였다. 이를 위하여, 세포표면 소수성 상호작용력(cell surface hydrophobicity), 자가응집력(autoaggregation), 세포에 부착하는 능력(cell adhesion)과 자가응집력(autoaggregation), LPS와의 결합력을 조사하였다. 또한 HT-29 장상피세포에서 LPS로 유도되는 IL-8의 발현을 억제하는 효과를 조사하였다. CBT LA1을 80도에서 121도까지 10분 동안 열을 처리하였을 때, 80도에서 열을 처리한 CBT LA1 사균체가 가장 높은 세포에 부착하는 능력을 보여 주었다. CBT LA1 생균과 비교했을 때, 80도에서 열을 처리한 CBT LA1 사균체는 높은 LPS와의 결합력, 소수성 상호작용력, 자가응집력, HT-29 세포에 부착하는 능력과 IL-8의 발현을 억제하는 능력을 보여주었다. In vivo 실험에서 FITC로 label된 LPS를 투여하였을 때 16시간 후, CBT LA1 사균체를 섭취한 동물의 장관 내 LPS가 가장 많이 제거되었다. 이러한 연구 결과들은 CBT LA1 생균처럼 CBT LA1 사균체도 장관장벽 기능을 가지며 이는, 파마바이오틱스로서 그 가능성을 시사한다.

• 한국환경보건학회지
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• 제13권1호
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• pp.47-57
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• 1987

Owing to the modification of testing methods of disinfectants or antiseptics, variations of bacteria according to characteristics of regions and resistance changes of bacteria, it is necessary that the bactericidal activities of disinfectants or antiscptics should be reevaluated nowadays. This study was carried out to reevaluate in the vitro bactericidal activity of Chlorhexidine gluconate solution. The results of experiment were summarized as follows. 1. For Chlorhexidine gluconate solution, minimal inhibitory concentrations of total bacteria taken from sewage water and Legionella bozemanii were $2.0\times 10^{-3}$%, $1.0\times 10^{-2}$%, respectively and were comparatively high. Minimal inhibitory concentration of Shigella flexneri was $1.6\times 10^{-4}$%, and was comparatively low. 2. For total bacteria taken from sewage water, it was killed within 15 minute in 0.1% Chlorhexidine gluconate solution when number of cells was $1.6\times 10^7$/ml. 3. For 0.0125% Chlorhexidine gluconate solution, decimal reduction times of Ps. aeruginosa, S. typhi, E. Coli were 45 sec, 25 sec, 18 sec repectively. For 1%, 0.125% Chlorhexidine gluconate solution, decimal reduction times of Legionella bozemanii were 10 sec, 45 sec respectively. 4. There was significant difference in the bactericidal activity of Chlorhexidine gluconate solution according to temperattire. Phenol coefficient of Chlorhexidine gluconate solution as using Staph. aureus was 100 and comparatively higher than that of other disinfectants. In comparison with other disinfectants, Legionella bozemanii was killed within 5 minutes in 0.02% KMnO$_4$ and 0.125% Chlorhexidine giuconate solution but was not killed within 3 minutes in 1% 0-cresol, 1% Phenol.

• 한국어병학회지
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• 제25권3호
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• pp.159-164
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• 2012

Vibrio vulnificus ghosts (VVG) were generated using a mobilizable vector including a thermosensitive expression cassette by conjugation. The vaccine potential of VVG was investigated in mouse. Mice immunized with VVG showed significantly higher antibody titer than those with formalin-killed V. vulnificus. The present study supports the conceptive usefulness of bacterial ghosts as vaccine candidates.

• Journal of Microbiology and Biotechnology
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• 제32권5호
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• pp.638-644
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• 2022

Probiotics modulate the gut microbiota, which in turn regulate immune responses to maintain balanced immune homeostasis in the host. However, it is unclear how probiotic bacteria regulate immune responses. In this study we investigated the immunomodulatory effects of heat-killed probiotics, including Lactiplantibacillus plantarum KC3 (LP3), Lactiplantibacillus plantarum CKDB008 (LP8), and Limosilactobacillus fermentum SRK414 (LF4), via phagocytosis, nitric oxide (NO), and pro-inflammatory cytokine production in macrophages. We thus found that heat-killed LP8 could promote the clearance of foreign pathogens by enhancing the phagocytosis of macrophages. Treatment with heat-killed LP8 induced the production of NO and pro-inflammatory cytokines, including TNF-α, IL-6, and IL-1β. In addition, heat-killed LP8 suppressed the production of NO and cytokines in LPS-induced RAW264.7 cells, suggesting that heat-killed LP8 exerts immunomodulatory effects depending on the host condition. In sum, these results indicate that heat-killed LP8 possesses the potential for immune modulation while providing a molecular basis for the development of functional probiotics prepared from inactivated bacterial cells.

• Journal of Microbiology and Biotechnology
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• 제29권12호
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• pp.1894-1903
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• 2019

The purpose of this study was to determine the probiotic properties of Lactobacillus brevis KCCM 12203P isolated from the Korean traditional food kimchi and to evaluate the antioxidative activity and immune-stimulating potential of its heat-killed cells to improve their bio-functional activities. Lactobacillus rhamnosus GG, which is a representative commercial probiotic, was used as a comparative sample. Regarding probiotic properties, L. brevis KCCM 12203P was resistant to 0.3% pepsin with a pH of 2.5 for 3 h and 0.3% oxgall solution for 24 h, having approximately a 99% survival rate. It also showed strong adhesion activity (6.84%) onto HT-29 cells and did not produce β-glucuronidase but produced high quantities of leucine arylamidase, valine arylamidase, β-galactosidase, and N-acetyl-β-glucosaminidase. For antioxidant activity, it appeared that viable cells had higher radical scavenging activity in the 2,2-diphenyl-1-picryl-hydrazyl (DPPH) assay, while in the 2-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) assay, heat-killed cells had higher antioxidant activity. Additionally, L. brevis KCCM 12203P showed higher lipid oxidation inhibition ability than L. rhamnosus GG; however, there was no significant difference (p < 0.05) between heat-killed cells and control cells. Furthermore, heat-killed L. brevis KCCM 12203P activated RAW 264.7 macrophage cells without cytotoxicity at a concentration lower than 10⁸ CFU/ml and promoted higher gene expression levels of inducible nitric oxide synthase, interleukin-1β, and interleukin-6 than L. rhamnosus GG. These results suggest that novel L. brevis KCCM 12203P could be used as a probiotic or applied to functional food processing and pharmaceutical fields for immunocompromised people.