• Microbiology and Biotechnology Letters
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• v.47 no.4
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• pp.596-602
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• 2019

In September 2017, the rhizospheric soil of Tetragonia tetragonoides (Pall.) Kuntze was further sampled. One hundred and thirty eight species of microorganisms were isolated from the soil. Indole-3-acetic acid (IAA) production, siderophore production, and phosphate degradation were examined in order to confirm bacterial growth from isolated microorganisms. As a result, most strains were able to produce auxins or siderophores and to solubilize phosphate. In addition, 138 isolated strains were treated with tobacco extract and conferred pathogen resistance to host plants upon treatment. As a result, 35 strains that were able to reduce pathophysiology by more the 60% were selected. Among them, 6 strains with high induced systemic resistance (ISR) activity were found. All of these strains belong to the genus Bacillus according to the 16S rDNA sequence analysis. Bacillus aryabhattai KUDC6619 showed outstanding effects with reduced infection in tobacco and pepper plants. Probably, these Bacillus species play a beneficial role by association with T. tetragonoides for its survival in the harsh conditions found on the island of Dokdo.

• Journal of Microbiology and Biotechnology
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• v.23 no.8
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• pp.1159-1166
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• 2013

Orientia tsutsugamushi, a gram-negative bacterium, causes severe acute febrile illness in humans. Despite this danger, the route of infection, infectivity, and protective mechanisms of the host's immune response to O. tsutsugamushi are unclear. Dendritic cells (DCs) are one of the most important cell types in bridging the innate and adaptive immune responses. In this study, we observed that O. tsutsugamushi infects and replicates in monocyte-derived DCs (MODCs). During infection and replication, the expressions of the cytokines IL-12 and TNF-${\alpha}$, as well as the co-stimulatory molecules CD80, CD83, CD86, and CD40, were increased in MODCs. When O. tsutsugamushi-treated MODCs were co-cultured with autologous $CD4^+$ T cells, they enhanced production of IFN-${\gamma}$, a major Th1 cytokine. Collectively, our results show that O. tsutsugamushi can replicate in MODCs and can simultaneously induce MODC maturation and increase proinflammatory cytokine levels in MODCs that subsequently activate $CD4^+$ T cells.

• Journal of Microbiology and Biotechnology
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• v.27 no.8
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• pp.1529-1538
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• 2017

Klebsiella pneumoniae is an opportunistic and clinically significant emerging pathogen. We investigated the relative roles of Toll-like receptor (TLR) 2 and TLR4 in initiating host defenses against K. pneumoniae. TLR2 knockout (KO), TLR4 KO, TLR2/4 double KO (DKO), and wild-type (WT) mice were inoculated with K. pneumoniae. Mice in each group were sacrificed after either 12 or 24h, and the lungs, liver, and blood were harvested to enumerate bacterial colony-forming units (CFU). Cytokine and chemokine levels were analyzed using enzyme-linked immunosorbent assay and real-time PCR, and pneumonia severity was determined by histopathological analysis. Survival was significantly shortened in TLR4 KO and TLR2/4 DKO mice compared with that of WT mice after infection with $5{\times}10^3CFU$. TLR2 KO mice were more susceptible to infection than WT mice after exposure to a higher infectious dose. Bacterial burdens in the lungs and liver were significantly higher in TLR2/4 DKO mice than in WT mice. Serum $TNF-{\alpha}$, MCP-1, MIP-2, and nitric oxide levels were significantly decreased in TLR2/4 DKO mice relative to those in WT mice, and TLR2/4 DKO mice showed significantly decreased levels of $TNF-{\alpha}$, IL-6, MCP-1, and inducible nitric oxide synthase mRNA in the lung compared with those in WT mice. Collectively, these data indicate that TLR2/4 DKO mice were more susceptible to K. pneumoniae infection than single TLR2 KO and TLR4 KO mice. These results suggest that TLR2 and TLR4 play cooperative roles in lung innate immune responses and bacterial dissemination, resulting in systemic inflammation during K. pneumoniae infection.

• Food Science of Animal Resources
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• v.24 no.1
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• pp.86-91
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• 2004

The ability of probiotics containing Lactobacillus acidophilus to adhere to the intestinal epithelium may play an important role in colonization of the gastrointestinal tract and preventing enteric pathogen such as enterohemorrhagic E. coli(EHEC O157:H7. In the study, we investigated the adhesion to human intestinal epithelial cells(HT-29) of strains of L. acidophilus(3 from human, 2 from pig, and 1 from calf). All of the tested strains of L. acidophilus were highly observed adhesion ability(from 10$\^$6/ to 10$\^$7/ cfu/mL), compared to L. rhamnosus GG as control. Also, adhered strains of L. acidophilus were significantly preserved in serial wash-out steps. However, no correlation could be observed between cell surface hydrophobicity and adhesion abilities of the tested strains of L. acidophilus. Inhibition of adhesion of EHEC O157:H7 was also examined, a 2 log cycle reduction was observed by all of the tested strains of L. acidophilus. These results suggest that the strains of L. acidophilus with high adhesion ability are resistant to wash-out and adhesion ability inhibition by selected strains of L. acidophilus helps to prevent adhesion of EHEC O157:H7 to intestinal epithelial cells.

• Asian Journal of Turfgrass Science
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• v.19 no.2
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• pp.85-94
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• 2005

A fungal isolate was newly collected from Zoysiagrass 'Anyang-Joongji' in small circular patches on a fairway ofa golf course in Korea, which seriously occurred during the early summer period of 2005. The isolate presented on PDAmedium, named Scz1, was closely identical to Sclerotinia homoeocarpa, a casual fungus of dollar spot disease, in cool season turf grasses such as creeping bentgrass. Hereby, this study was accomplished to characterize the isolate and compare it with the fungus, named Scb1, isolated from dollar spot-infected creeping bentgrass (Agrostis palustris Huds. cv Penncross). On PDAmedium, individual mycelial appearance of three isolates was very similar except for the pigment. Mycelial pigments of Scz1 and Scz2 (another analogous isolate collected) were light pinkish on the reverse side of PDA medium but that of Scb1 was dark brownish. In a microscopic study, three isolates were barely distinguishable in the appearance of mycelia. As expected, in the temperaturesensitivity assay, all pathogens were very delicate to $32^{circ}C$ above but not to $30^{circ}C$ below, in which was explained to be one of typical characteristics in S. homoeocarpa. In an artificial inoculation assay, disease symptoms including leaf spots in Zoysiagrass were appeared within 6-7 days after inoculation through the hand inoculation method with the isolate-infested soil. Then the fungus was re-identified from the infected leaf tissues. Interestingly, inoculation of isolate Scz1 gave rise to distinct symptoms in only Zoysiagrass but not in creeping bentgrass 'Penncross' and Kentucky bluegrass 'Midnight'. The observation might be involved in host specific pathogenecity of S. homoeocarpa Scz1 to Zoysiagrass. In a chemical sensitivity assay for the isolate, Scz1, showed a high mycelial inhibition against two fungicides, iprodione and propiconazole. All results described above suggest that S. homoeocarpa Scz1 is a primary pathogen of Zoysia dollar spot disease.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.4
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• pp.1247-1251
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• 2012

Background: Helicobacter pylori is an important gastrointestinal pathogen related to the development of not only atrophic gastritis and peptic ulcer, but also gastric cancer. Human leukocyte antigens (HLA) may play particular roles in host immune responses to bacterial antigens. This study aimed to investigate the association between HLA-DQA1 and DQB1 genotypes and haplotypes vs H. pylori infection in an Indonesian population. Methods: We selected 294 healthy participants in Mataram, Lombok Island, Indonesia. H. pylori infection was determined by urea breath test (UBT). We analyzed HLA-DQA1 and DQB1 genotypes by PCR-RFLP and constructed haplotypes of HLA-DQA1 and DQB1 genes. Multiple comparisons were conducted according to the Bonferroni method. Results: The H. pylori infection rate was 11.2% in this Indonesian population. The DQB1*0401 genotype was noted to be associated with a high risk of H. pylori infection, compared with the DQB1*0301 genotype. None of the HLA-DQA1 or DQB1 haplotypes were related to the risk of H. pylori infection. Conclusions: The study suggests that HLADQB1 genes play important roles in H. pylori infection, but there was no statistically significant association between HLA-DQA1 or DQB1 haplotypes and H.pylori infection in our Lombok Indonesian population.

• Korean Journal Plant Pathology
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• v.3 no.3
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• pp.210-216
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• 1987

A computer program written to predict blast occurrence based on micro climatic events was developed and tested as an on-site microcomputer in field plots in 1984 and 1985. A microcomputer unit operating on alkaline batteries; continuously monitored air temperature, leaf wetness, and relative humidity; interpreted the microclimate information in relation to rice blast development and displayed daily values (0-8) of blast units of severity (BUS). Cumulative daily BUS values (CBUS) were highly correlated with blast development on the two susceptible cultivars, M-201 and Brazos grown in field plots. When CBUS values were used to predict the logit of disease proportions, the average coefficients of determination $(R^2)$ between these two factors were 71 to $91\%$, depending on cultivar and year. This was a significant improvement when compared to 61 to $79\%$ when days were used as a predictor of logit disease severity. The ability of CBUS to predict logit disease severity was slightly less with Brazos than M-201. This is significant inasmuch as Brazos showed field resistance at mid-sea­son. The results in this study indicate that the model has the potential for future use and that the model could be improved by incorporating other variables associated with host plants and pathogen races in addition to the key environmental variables.

• BMB Reports
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• v.49 no.10
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• pp.554-559
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• 2016

Mycobacterium abscessus, a member of the group of non-tuberculous mycobacteria, has been identified as an emerging pulmonary pathogen in humans. However, little is known about the protective immune response of antigen-presenting cells, such as dendritic cells (DCs), which guard against M. abscessus infection. The M. abscessus gene MAB1843 encodes ᴅ-alanyl-ᴅ-alanine dipeptidase, which catalyzes the hydrolysis of ᴅ-alanyl-ᴅ-alanine dipeptide. We investigated whether MAB1843 is able to interact with DCs to enhance the effectiveness of the host's immune response. MAB1843 was found to induce DC maturation via toll-like receptor 4 and its downstream signaling pathways, such as the mitogen-activated protein kinase and nuclear factor kappa B pathways. In addition, MAB1843-treated DCs stimulated the proliferation of T cells and promoted Th1 polarization. Our results indicate that MAB1843 could potentially regulate the immune response to M. abscessus, making it important in the development of an effective vaccine against this mycobacterium.

• The Plant Pathology Journal
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• v.18 no.5
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• pp.293-299
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• 2002

A survey of Fusarium wilt of perilla was conducted in 12 locations in Korea from 1999 to 2001. The disease occurred in 74 out of 187 fields in the 12 locations surveyed, and incidence of the disease reached up to 30% at its maximum in some perilla fields in Seosan and Dangjin. Incidence of the disease in the other locations ranged from 0.2 to 20%. A total of 327 isolates of Fusarium spp. were obtained from stems and roots of the diseased perilla plants. The isolates were identified based on their morphological characteristics. Out of the 327 isolates of Fusarium, 277 isolates from 12 locations were identified as F. oxysporum, 11 isolates from three locations as F. solani,17 isolates from two locations as F. equiseti, 4 isolates from one location as F. avenaceum and 6 isolates from one location as F. subglutinans. The other 12 isolates of Fusarium from four locations were unidentified. Twelve isolates of F. oxysporum and two isolates each of the other Fusarium spp. were tested for their pathogenicity to five cultivars of perilla. Seven isolates of F. oxysporum were strongly pathogenic to some perilla cultivars, but the other five isolates were weakly or not pathogenic. One isolate of F. solani was strongly pathogenic to all the perilla cultivars tested, but another isolate was not pathogenic. All the isolates of F. equiseti, F. avenaceum, and F. Subglutinans tested were not pathogenic to any of the perilla cultivars tested. Symptoms on the perilla plants induced by artificial inoculation with strongly pathogenic isolates of F. oxysporum and F. solani appeared as wilt, stem blight, and root yet, which were similar to those observed in the fields. The isolates which induced symptoms by artificial inoculation were re-isolated from the lesions of the perilla plants inoculated. All the isolates of F. oxysporum tested were not pathogenic to eight other crops inoculated. Results of this study reveal that F. oxysporum is the main pathogen of perilla wilt and that it is host specific to perilla. forma specialis of F. oxysporum causing wilt of perilla is proposed as perillae.

• 한국균학회소식:학술대회논문집
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• 2015.11a
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• pp.41-41
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• 2015

Oomycetes belong to the kingdom Straminipila, a remarkably diverse group which includes brown algae and planktonic diatoms, although they have previously been classified under the kingdom Fungi. These organisms have evolved both saprophytic and pathogenic lifestyles, and more than 60% of the known species are pathogens on plants, the majority of which are classified into the order Peronosporales (includes downy mildews, Phytophthora, and Pythium). Recent phylogenetic investigations based on DNA sequences have revealed that the diversity of oomycetes has been largely underestimated. Although morphology is the most valuable criterion for their identification and diversity, morphological species identification is time-consuming and in some groups very difficult, especially for non-taxonomists. DNA barcoding is a fast and reliable tool for identification of species, enabling us to unravel the diversity and distribution of oomycetes. Accurate species determination of plant pathogens is a prerequisite for their control and quarantine, and further for assessing their potential threat to crops. The mitochondrial cox2 gene has been widely used for identification, taxonomy and phylogeny of various oomycete groups. However, recently the cox1 gene was proposed as a DNA barcode marker instead, together with ITS rDNA. To determine which out of cox1 or cox2 is best suited as universal oomycete barcode, we compared these two genes in terms of (1) PCR efficiency for 31 representative genera, as well as for historic herbarium specimens, and (2) in terms of sequence polymorphism, intra- and interspecific divergence. The primer sets for cox2 successfully amplified all oomycete genera tested, while cox1 failed to amplify three genera. In addition, cox2 exhibited higher PCR efficiency for historic herbarium specimens, providing easier access to barcoding type material. In addition, cox2 yielded higher species identification success, with higher interspecific and lower intraspecific divergences than cox1. Therefore, cox2 is suggested as a partner DNA barcode along with ITS rDNA instead of cox1. Including the two barcoding markers, ITS rDNA and cox2 mtDNA, the multi-locus phylogenetic analyses were performed to resolve two complex clades, Bremia lactucae (lettuce downy mildew) and Peronospora effuse (spinach downy mildew) at the species level and to infer evolutionary relationships within them. The approaches discriminated all currently accepted species and revealed several previously unrecognized lineages, which are specific to a host genus or species. The sequence polymorphisms were useful to develop a real-time quantitative PCR (qPCR) assay for detection of airborne inoculum of B. lactucae and P. effusa. Specificity tests revealed that the qPCR assay is specific for detection of each species. This assay is sensitive, enabling detection of very low levels of inoculum that may be present in the field. Early detection of the pathogen, coupled with knowledge of other factors that favor downy mildew outbreaks, may enable disease forecasting for judicious timing of fungicide applications.