• Journal of Environmental Science International
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• v.21 no.3
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• pp.267-276
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• 2012

Spaceflights results in the reduction of immune status of human beings and increase in the virulence of microorganisms, especially gram negative bacteria. The growth of Klebsiella pneumoniae is enhanced by catecholamines and during spaceflight, elevation in the levels of cortisols occurs. So it is necessary to know the changes in physiology, virulence, antibiotic resistance and gene expression of K. pneumoniae under microgravity conditions. The present study was undertaken to study effect of simulated microgravity on growth, morphology, antibiotic resistance and cross stress resistance of K. pneumoniae to various stresses. The susceptibility of simulated microgravity grown K. pneumoniae to ampicillin, penicillin, streptomycin, kanamycin, hygromycin and rifampicin were evaluated. The growth of bacteria was found to be fast compared with normal gravity grown bacteria and no significant changes in the antibiotic resistance were found. The bacteria cultured under microgravity conferred cross stress resistance to acid, temperature and osmotic stress higher than the normal gravity cultured bacteria but the vice versa was found in case of oxidative stress.

• Genomics & Informatics
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• v.21 no.2
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• pp.21.1-21.14
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• 2023

Fusobacterium nucleatum is a gram-negative bacteria associated with diverse infections like appendicitis and colorectal cancer. It mainly attacks the epithelial cells in the oral cavity and throat of the infected individual. It has a single circular genome of 2.7 Mb. Many proteins in F. nucleatum genome are listed as "Uncharacterized." Annotation of these proteins is crucial for obtaining new facts about the pathogen and deciphering the gene regulation, functions, and pathways along with discovery of novel target proteins. In the light of new genomic information, an armoury of bioinformatic tools were used for predicting the physicochemical parameters, domain and motif search, pattern search, and localization of the uncharacterized proteins. The programs such as receiver operating characteristics determine the efficacy of the databases that have been employed for prediction of different parameters at 83.6%. Functions were successfully assigned to 46 uncharacterized proteins which included enzymes, transporter proteins, membrane proteins, binding proteins, etc. Apart from the function prediction, the proteins were also subjected to string analysis to reveal the interacting partners. The annotated proteins were also put through homology-based structure prediction and modeling using Swiss PDB and Phyre2 servers. Two probable virulent factors were also identified which could be investigated further for potential drug-related studies. The assigning of functions to uncharacterized proteins has shown that some of these proteins are important for cell survival inside the host and can act as effective drug targets.

• Microbiology and Biotechnology Letters
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• v.51 no.4
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• pp.507-516
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• 2023

Eradication of Helicobacter pylori infection is an essential strategy to decrease the risk of developing gastric cancer. However, the standard triple therapy has negative aspects associated with side effects and the emergence of antibiotic resistance. Therefore, alternative therapies are required to enhance the management of H. pylori infection effectively. In this study we examined the effect of emodin on the amelioration of inflammatory response due to H. pylori infection. Our results indicated that emodin treatment effectively decreased the expression of virulence genes, including sabA, vacA, cagL, cagA, sabA, and suppressed the adhesion ability of H. pylori to AGS cells. Emodin has been shown inhibitory effects on the inflammasome pathway through reductions in VacA translocation, lowering ROS stress, cleaved Caspase-1, NLRP3, and cleaved Gasdermin D levels, thereby lowered pyroptosis in infected cells. In summary, our study demonstrated that emodin has the ability to attenuate inflammation caused by H. pylori by modulating virulence gene expression and decreasing VacA translocation. Further study is required to evaluate the therapeutic efficacy of emodin in treating H. pylori infection and better understand the underlying mechanisms.

• Korean Journal of Food Science and Technology
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• v.47 no.1
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• pp.126-131
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• 2015

Pathogenic Escherichia coli is recognized as an important cause of diarrhea, hemorrhagic colitis and hemolytic-uremic syndrome worldwide. This study was conducted to investigate the prevalence E. coli contamination in the Korean traditional food bibimbap. E. coli were isolated from 84 of 1142 (7.3%) bibimbap investigated from 2005 to 2011. Antibiotic resistance profiling demonstrated that 6 of the 84 isolates (7.2%) showed multiple drug resistance. Fifteen virulence genes specific for pathogenic E. coli such as Shiga toxin-producing E. coli (STEC), enteropathogenic E. coli (EPEC), enterotoxigenic E. coli (ETEC), enteroinvasive E. coli (EIEC), and enteroaggregative E. coli (EAEC) were examined by multiplex PCR for mixed bacterial cultures derived from bibimbap samples. The EPEC virulence gene (ent) was detected in 5 strains (5.9%), while ETEC, EAEC, and EIEC were not detected. STEC serotypes O103 (1.2%), O91 (1.2%), and O128 (6.0%) were found, but other serogroups such as O26, O157, O145, O111 and O121 were not detecded. Automated Repetitive-Sequence-Based PCR analysis showed different patterns.

• Microbiology and Biotechnology Letters
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• v.36 no.1
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• pp.6-11
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• 2008

To check the microbiological safety with respect to increased virulence of surviving pathogens after irradiation, in this study, the transcriptional change of vvp gene encoding metalloprotease, which is one of the typical virulence factors of Vibrio mulnificus, was monitored by real-time PCR during the course of growth cycle after reinoculation of irradiated Vibrio. When V. vulnificus was exposed to a dose of 0.5 and 1 kGy, the lag period before growth resumption of sub-cultures became longer than non-irradiated counterpart as increase of irradiation dose. In the case of non-irradiated culture, the transcription of vvp was significantly activated at 15 h after inoculation, when bacterial growth reached the stationary phase, and the highest level of pretense activity (686 U/mL) was measured at the same time. Interestingly, vvp expression of irradiated Vibrio was turned up earlier than non-irradiated Vibrio during the mid log phase of growth, whereas these rapid induction of vvp expression from irradiated cells didn't result in an increase of metalloprotease production. When Vibrio was irradiated at 0.5 and 1 kGy, the protease activities peaked at 18 h after inoculation and the levels of activities were lower 1.2- and 1.4-fold, respectively, compared to the non-irradiated counterpart. Results from this study indicate that gamma radiation is not likely to activate the virulence ability of surviving Vibrio.

• Journal of Microbiology and Biotechnology
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• v.30 no.4
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• pp.571-582
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• 2020

Quorum sensing (QS)-mediated infections cause severe diseases in human beings. The control of infectious diseases by inhibiting QS using antipathogenic drugs is a promising approach as antibiotics are proving inefficient in treating these diseases. Marine fungal (Pestalotiopsis sydowiana PPR) extract was found to possess effective antipathogenic characteristics. The minimum inhibitory concentration (MIC) of the fungal extract against test pathogen Pseudomonas aeruginosa PAO1 was 1,000 ㎍/ml. Sub-MIC concentrations (250 and 500 ㎍/ml) of fungal extract reduced QS-regulated virulence phenotypes such as the production of pyocyanin, chitinase, protease, elastase, and staphylolytic activity in P. aeruginosa PAO1 by 84.15%, 73.15%, 67.37%, 62.37%, and 33.65%, respectively. Moreover, it also reduced the production of exopolysaccharides (74.99%), rhamnolipids (68.01%), and alginate (54.98%), and inhibited the biofilm formation of the bacteria by 90.54%. In silico analysis revealed that the metabolite of P. sydowiana PPR binds to the bacterial QS receptor proteins (LasR and RhlR) similar to their respective natural signaling molecules. Cyclo(-Leu-Pro) (CLP) and 4-Hydroxyphenylacetamide (4-HPA) were identified as potent bioactive compounds among the metabolites of P. sydowiana PPR using in silico approaches. The MIC values of CLP and 4-HPA against P. aeruginosa PAO1 were determined as 250 and 125 ㎍/ml, respectively. All the antivirulence assays were conducted at sub-MIC concentrations of CLP (125 ㎍/ml) and 4-HPA (62.5 ㎍/ml), which resulted in marked reduction in all the investigated virulence factors. This was further supported by gene expression studies. The findings suggest that the metabolites of P. sydowiana PPR can be employed as promising QS inhibitors that target pathogenic bacteria.

• Journal of the Korea Convergence Society
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• v.6 no.5
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• pp.77-84
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• 2015

This study was conducted to investigate the characteristics of antibiotic resistant E. coli. its antibiotic susceptibility and pathogenicity were analyzed via molecular convergence technique, for the relationship of antibiotic susceptibility and pathogenicity. The 60 isolated strains consisted of ESBL(+)(8) and ESBL(-)(52) strains. The ESBL(+)(8) strains consisted of 2 strains without a pathogenic gene, stb(3), flich7(1), and flich7-eae(2). The ESBL(-)(52) strains consisted of 26 strains without a pathogenic gene, stx1(3), stb(10), flich7(2), eae(2), stx1-flich7(2), stx1-stb(4), flich7-stb(2), and flich7-stb-eae(1). In conclusion, antibiotic resistance is increasingly, Focused on molecular convergence, showed the correlation of pathogenicity with antibiotic resistance was poor. However, It will be able to find the exact pathogenic factor in the future through convergence technique including the analysis of virulence genes.

• Journal of Food Hygiene and Safety
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• v.39 no.3
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• pp.231-238
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• 2024

Vibrio parahaemolyticus is a major seafood-borne pathogen commonly detected in marine environments. In Korea, V. parahaemolyticus-induced foodborne illnesses account for 7.5% of bacterial pathogen-related food poisonings. Moreover, the amount of antimicrobial agents used in aquatic cultures is continuously increasing. In this study, we isolated V. parahaemolyticus from seafood samples and performed antimicrobial susceptibility tests using the microbroth dilution method. Furthermore, using whole-genome sequencing, we identified antimicrobial resistance genes, virulence genes, and sequence types (STs). We could isolate V. parahaemolyticus from 47 (59.5%) of the 79 seafood samples we purchased from retail markets in Seoul and Chungcheong provinces. Antimicrobial susceptibility tests revealed that 2 and all of the 47 isolates were ampicillin-resistant (4.3%) and susceptible to all tested antimicrobial agents (100%), respectively. The genotype analysis revealed that all isolates carried beta-lactam-, tetracycline-, and chloramphenicol-associated antimicrobial resistance genes. However, we could detect fosfomycin resistance only in one isolate. Concerning the virulence genes, we detected T3SS1 and T3SS2-associated genes in all and one isolate, respectively. However, we could not detect the tdh and trh genes. Of the 47 isolates, 17 belonged to 15 different STs, including ST 658 with 3 isolates. The rest 30 isolates were identified as 25 new STs. The results of this study support the need for operating a continuous monitoring system to prevent foodborne illnesses and the spread of antimicrobial resistance genes in V. parahaemolyticus.

• Korean Journal of Veterinary Service
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• v.26 no.1
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• pp.39-50
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• 2003

Non-typhoidal Salmonella serovars remain a potential threat to human health and many animals including beef cattle, broiler chickens, and pigs which possible sources of non-typhoidal salmonellosis in human. In this study, the cecal contents of slaughtered pigs were examined for Salmonella serovar prevalence. The characteristics of the isolates, including antimicrobial resistance patterns and virulence genes, were studied along with the reference strain S typhimurium ATCC 13311. Out of 640 sample, 137 Salmonella(21.4%) were isolated and their serovar were identified S typhimurium 83 strains(60.6%), S agona 10 strains(7.3%), S schwarzengrund 4 strains(2.9%), S derby 4 strains(2.9%), S ayinde 1 strains(0.7%), and untypable 35 strains(25.5%). All 83 S typhimurium strains(100%) were multi-drug resistance to at least 7 antibiotics, and 20 strains(24.1%) of 83 isolates were R-type ACSSuT. Examination of virulent gene by PCR revealed that 73 S typimurium field isolates(88%) have a invA gene and 24 strains(28.9%) have a spvC gene. Consequently, S typhimurium infection in slaughtered pigs was relatively to appear high prevalence in their herds which suggested that it should be necessary for herd health monitoring and surveillance.

• Molecules and Cells
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• v.39 no.9
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• pp.705-713
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• 2016

The efficiency of Agrobacterium-mediated transformation in plants depends on the virulence of Agrobacterium strains, the plant tissue culture conditions, and the susceptibility of host plants. Understanding the molecular interactions between Agrobacterium and host plant cells is crucial when manipulating the susceptibility of recalcitrant crop plants and protecting orchard trees from crown gall disease. It was discovered that Arabidopsis voltage-dependent anion channel 1 (atvdac1) mutant has drastic effects on Agrobacterium-mediated tumorigenesis and growth developmental phenotypes, and that these effects are dependent on a Ws-0 genetic background. Genetic complementation of Arabidopsis vdac1 mutants and yeast porin1-deficient strain with members of the AtVDAC gene family revealed that AtVDAC1 is required for Agrobacterium-mediated transformation, and there is weak functional redundancy between AtVDAC1 and AtVDAC3, which is independent of porin activity. Furthermore, atvdac1 mutants were deficient in transient and stable transformation by Agrobacterium, suggesting that AtVDAC1 is involved in the early stages of Agrobacterium infection prior to transferred-DNA (T-DNA) integration. Transgenic plants overexpressing AtVDAC1 not only complemented the phenotypes of the atvdac1 mutant, but also showed high efficiency of transient T-DNA gene expression; however, the efficiency of stable transformation was not affected. Moreover, the effect of phytohormone treatment on competence to Agrobacterium was compromised in atvdac1 mutants. These data indicate that AtVDAC1 regulates the competence of Arabidopsis to Agrobacterium infection.