• 한국미생물·생명공학회지
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• 제48권3호
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• pp.276-286
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• 2020

Probiotics are live microorganisms that, when administered in adequate amounts, confer health benefits to the host. This study was conducted for the isolation of potential lactic acid bacteria (LAB) with probiotic properties from goat milk and yogurt. Several tests were conducted in vitro using the standard procedures for evaluating the inhibitory spectra of LAB against pathogenic bacteria; tolerance to NaCl, bile salt, and phenol; hemolytic, milk coagulation, and bile salt hydrolase activities; gastrointestinal transit tolerance; adhesion properties; and antibiotic susceptibility. Among 40 LAB strains screened according to culture characteristics, five isolates exhibited antagonistic properties. Three were identified as Pediococcus acidilactici, and two were identified as Enterococcus faecium, exploiting 16S rRNA gene sequencing. All the isolates succeeded in the gastrointestinal transit tolerance assay and successively colonized mucosal epithelial cells. Based on the results of these in vitro assays, both P. acidilactici and E. faecium can be considered as potential probiotic candidates.

• 한국균학회지
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• 제24권4호통권79호
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• pp.246-254
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• 1996

1980년대 중반이후로 우리나라에서 영지의 재배면적과 생산량은 매년 증가해 오고 있지만 1980년대 말기부터 강화, 철원, 신탄지 등지에서 발생하기 시작한 새로운 병원성 진균의 출현에 의해서 영지재배는 막대한 경제적 손실을 입고 있으며 영지재배의 제한적 요인이 되고 있는 실정이다. 이 연구는 영지재배시에 발생하는 새로운 진균성 병해의 효과적인 방제수단을 찾기 위한 노력의 일환으로 병원성 진균을 분리하고 동정하기 위하여 실시되었다. 병원균에 의해 감염된 영지재배 원목에서 분리한 균주가 인공 접종시 전형적인 병징을 나타낼 수 있는지 병원성 검정을 실시하였고, 병원성 진균에 의해서 생성되는 병징, 균사, 분절포자, 자낭과, 자낭포자 등을 육안, 해부현미경, 광학현미경, 주사전자현미경 등을 사용하여 관찰하였다. 이 병원균에 의하여 형성되는 자낭과는 성숙시 검은색의 두꺼운 막으로 된 구형으로 직경은 $45{\sim}95\;{\mu}m$로 크기가 다양하였다. 자낭은 막이 얇고 형성되는 즉시 없어지기 때문에 매우 관찰하기 어려우며 자낭포자는 구형으로 무색이며 비교적 두꺼운 막으로 싸여 반들반들하게 보이고 크기는 $3.6{\sim}4.3\;{\mu}m$ 정도로 균일하였다. 분생자병은 즉시 막이 두꺼워지고 격막으로 나누어지면서 분절포자가 형성되었고 분절포자는 원통형으로 길이가 $3{\sim}6\;{\mu}m$족이 $3{\sim}4\;{\mu}m$정도였다. 따라서 이상의 형태학적인 특성에 기초하여 이 병원균의 완전세대는 Xylogone sphaerospora Van Arx & Nilsson로, 불완전세대는 Sporendonema purpurascens (Bonordon) Mason & Hughes로 동정되었으며, 이 균은 영지의 병원균으로는 처음 보고되는 것이다.

• 대한미생물학회지
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• 제22권1호
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• pp.71-78
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• 1987

In order to determine the virulence properties of eleven strains of Sh. flexneri isolated from diarrheal patients the congo red test, the $Ser{\acute{e}}ny$ test, the HeLa cell invasion test and electrophoresis of plasmids were carried out. The results were summarized as follows. 1. Virulent strains were not determined by the result of Congo red absorption test. 2. Virulent strains showed positive reaction by the Sereny test and the HeLa cells invasion, but avirulent strains revealed negative reaction at those tests. 3. The temperature condition of bacterial growth was a factor of virulent expression. 4. Virulent strains were mostly possessed of a 130.3 Mdal plasmid, but avirulent strains were not.

• 대한미생물학회지
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• 제16권1호
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• pp.13-18
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• 1981

Total 984 specimens were collected from sweages(130 specimens) and human rectal swabs(854 specimens) during period from October 1979 to November 1980 in Korea. Sixteen strains of salmonella were isolated from the human rectal swabs at the St. Mary's Hospital in Dae Jeon. They were confirmed into fifteen strains of S. typhi, one strain of S. paratyphi A. In other hand, fourty three strains of Shigella had been isolated from the stool specimens. They were typed as thirty four strains of Shigella flexneri, five strains of Shigella sonnei and one strain of Shigella dysenteriae. However, 16 strains of Vibrio eltor had been isolated from patients and carriers in the first epidemic areas in Chunla Namdo in September 1980. The serotype of isolated strains was determined as a Inaba which was resistant to the Mukerjee phage group IV but was susceptible to El Tor phage groupe I and II. Authors had been concluded that the strains were certain to be identified with Vibrio cholerae biotype El Tor.

• Mycobiology
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• 제49권1호
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• pp.89-94
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• 2021

Forty-three (n = 43) endophytic fungi with different morphologic characteristics were from a medicinal plant Sceletium tortuosum, were utilized to investigate their antifungal effectiveness against pathogenic fungi. All fungal isolates exhibited antifungal activity against one or more pathogens in the dual culture test whereas only 33 fungal culture filtrates (77%) showed decent antifungal effect. Fusaria and Aspergillus were the dominate genus that displayed significant antifungal activity. Isolates GG02, GG09, ND15, and ND17 showed the broadest spectrum of antifungal activity. Furthermore, culture filtrate of Fusarium sp. DR08 exhibited a broad range of antifungal activity against all the pathogens. The results suggest endophytic fungi isolated from medicinal plant might be a source of novel bioactive molecules. To the best our knowledge, this is the first report on endophytic fungi isolated from native kougoed exhibiting antifungal activity against plant fungal pathogens.

• Journal of Microbiology and Biotechnology
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• 제32권8호
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• pp.955-959
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• 2022

Japanese encephalitis (JE) is a vaccine-preventable mosquito-borne disease caused by infection with the Japanese encephalitis virus (JEV). JEV has five genotypes, including genotype V (GV), which is considered ancestral to the other genotypes. The first GV strain, GV Muar, was isolated from a Malayan patient in 1952 and GV did not reappear for 57 years until GV XZ0934 was isolated from a mosquito sample in China. Since 2010, 21 GV strains have been identified in Republic of Korea (ROK). Both GV Muar and GV XZ0934 are more pathogenic than other GI/GIII strains and are serologically distinct. However, because the ROK's GV strains have not been experimentally tested, their characteristics are not known. Characterization of the ROK's isolates is needed to enable development of effective GV strain-based vaccines to protect against GV infections.

• Parasites, Hosts and Diseases
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• 제55권3호
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• pp.233-238
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• 2017

Pathogenic Naegleria fowleri, Acanthamoeba castellanii, and Acanthamoeba polyphaga, are distributed worldwide. They are causative agents of primary amoebic meningoencephalitis or acanthamoebic keratitis in humans, respectively. Trophozoites encyst in unfavorable environments, such as exhausted food supply and desiccation. Until recently, the method of N. fowleri encystation used solid non-nutrient agar medium supplemented with heat-inactivated Escherichia coli; however, for the amoebic encystment of Acanthamoeba spp., a defined, slightly modified liquid media is used. In this study, in order to generate pure N. fowleri cysts, a liquid encystment medium (buffer 1) modified from Page's amoeba saline was applied for encystation of N. fowleri. N. fowleri cysts were well induced after 24 hr with the above defined liquid encystment medium (buffer 1). This was confirmed by observation of a high expression of differential mRNA of nfa1 and actin genes in trophozoites. Thus, this liquid medium can replace the earlier non-nutrient agar medium for obtaining pure N. fowleri cysts. In addition, for cyst formation of Acanthamoeba spp., buffer 2 (adjusted to pH 9.0) was the more efficient medium. To summarize, these liquid encystment media may be useful for further studies which require axenic and pure amoebic cysts.

• International Journal of Oral Biology
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• 제43권4호
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• pp.217-222
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• 2018

Phagocytosis is a fundamental process in which phagocytes capture and ingest foreign particles including pathogenic bacteria. Several oral pathogens have anti-phagocytic strategies, which allow them to escape from and survive in phagocytes. Impaired bacteria phagocytosis increases inflammation and contributes to inflammatory diseases. The purpose of this study is to investigate the influences of various agents on oral pathogenic phagocytosis. To determine phagocytosis, Streptococcus mutans, Fusobacterium nucleatum, Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis were stained with 5-(and-6)-carboxyfluorescein diacetate succinimidyl ester (CFSE), and was measured using flowcytometery and confocal microscopy. The influencing factors on phagocytosis were evaluated through the pretreatment of ROS inhibitor (N-acetyl-L-cysteine (NAC)), lysozyme, potassium chloride (KCI) and adenosine triphosphate (ATP) in THP-1 cells. Expression of pro-inflammatory cytokines was determined by enzyme-linked immunosorbent assay (ELISA). The phagocytosis of various bacteria increased in a MOI-dependent manner. Among the tested bacteria, phagocytosis of P. gingivalis showed the highest fluorescent intensity at same infection time. Among the tested inhibitors, the NAC treatment significantly inhibited phagocytosis in all tested bacteria. In addition, NAC treatment indicated a similar pattern under the confocal microscopy. Moreover, NAC treatment significantly increased the bacteria-induced secretion of $IL-1{\beta}$ among the tested inhibitors. Taken together, we conclude that the phagocytosis occurs differently depending on each bacterium. Down-regulation by ROS production inhibited phagocytosis and lead increased of oral pathogens-associated inflammation.

• Journal of Microbiology and Biotechnology
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• 제15권6호
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• pp.1164-1169
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• 2005

Characteristics of sophorolipid and rhamnolipid were evaluated as antifungal agents against plant pathogenic fungi. Eight percent of mycelial growth of plant pathogen (Phytophthora sp. and Pythium sp.) was inhibited by 200 mg/l of rhamnolipid or 500 mg/l of sophorolipid, and zoospore motility of Phytophthora sp. decreased by $90\%$ at 50 mg/l of rhamnolipid and $80\%$ at 100 mg/l of sophorolipid. The effective concentrations for zoospore lysis were two times higher than those of zoospore motility inhibition. The highest zoospore lysis was observed with Phytophthora capsici; $80\%$ lysis at 100 mg/I of di-rhamnolipid or lactonic sophorolipid, showing the dependency of structure on the lysis. In the pot test, the damping-off disease incidence ratio decreased to $42\%\;and\;33\%$ of control value at 2,000 mg/l sophorolipid and rhamnolipid, respectively. These results showed the potential of microbial glycolipid biosurfactants as an effective antifungal agent against damping-off plant pathogens.

• Journal of Microbiology and Biotechnology
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• 제10권4호
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• pp.488-495
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• 2000

Strain SA72 was isolated from Jeot-gal and identified as producer of a bacteriocin, which showed some bactericidal activity against Lactobacillus delbrueckii ATCC 4797. Strain SA72 was tentatively identified as Lactococcus lactis according to the AOI test. Lactococcus lactis SA72 showed a broad spectrum of microorganisms, tested by the modified deferred method. The activity of lacticion SA72, named tentatively as a bacteriocin produced by Lactococcus lactis SA72, was detected during the mid-lon growth phase, reached a maximum during the early stationary phase, and then declined after the late stationary phase. Lacticin SA72 also showed a relatively broad spectrum of activity against non-pathogenic and pathogenic microorganisms when assessed by the spot-on-lawn method. Its anitimicrobial activity on sensitive indicator cells disappeared completely by protease XIV treatment. The inhibitory activity of lacticin SA72 remained after treatment for 15 min at $121^{\circ}C$, 문 was stable in a pH range of 2.0 to 9.0 and all organic solvents examined. It demonstrated a typical bactericidal mode of inhibition against Lactobacillus delbrueckii ATCC 4797. The apparent molecular mass of lacticin SA72 was in the region of 3-3.5 kDa, determined by SDS-PAGE.