• Mycobiology
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• v.40 no.2
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• pp.111-116
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• 2012

Ten strains of the entomopathogenic fungi Metarhizium anisopliae and Beauveria bassiana were evaluated to find the most effective strain for optimization studies. The first criterion tested for strain selection was the mortality (> 50%) of Spodoptera litura larvae after inoculation of the fungus for 4 days. Results on several bioassays revealed that B. bassiana BNBCRC showed the most virulence on mortality S. litura larvae (80% mortality). B. bassiana BNBCRC also showed the highest germination rate (72.22%). However, its conidia yield ($7.2{\times}10^8$ conidia/mL) was lower than those of B. bassiana B 14841 ($8.3{\times}10^8$ conidia/mL) and M. anisopliae M6 ($8.2{\times}10^8$ conidia/mL). The highest accumulative radial growth was obtained from the strain B14841 (37.10 mm/day) while the strain BNBCRC showed moderate radial growth (24.40 mm/day). M. anisopliae M6 possessed the highest protease activity (145.00 mU/mL) while M. anisopliae M8 possessed the highest chitinase activity (20.00 mU/mL) during 96~144 hr cultivation. Amongst these criteria, selection based on virulence and germination rate lead to the selection of B. bassiana BNBCRC. B. bassiana B14841 would be selected if based on growth rate while M. anisopliae M6 and M8 possessed the highest enzyme activities.

• Journal of Periodontal and Implant Science
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• v.23 no.1
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• pp.1-15
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• 1993

P. gingivalis has been implicated as a strong pathogen in periodontal disease and known to have three serotypes of P. gingivalis. The purpose of this study is to investigate on the relationship between virulence, metabolic acids and genetic heterogeneity of P. gingivalis. P. gingivalis W50 standard strain and five strains of P. gingivalis serotype b Korean isolates were used in this study. For in vitro virulence test, lyophilized whole cell P. gingivalis were suspended, and sonicated with ultrasonic dismembranometer. Sonicated samples were applied to cultured cells derived from periodontal ligament, and cell activity was assayed with growth and survival assay. The metabolic acids were also extracted, and determined by High Performance Liquid Chromatography. Pst I-digested bacterial genomic DNA was electrophoresed, and densitometric analysis was performed to study the genetic heterogeneity. All of the P. gingivalis serotype b produced butyric acid. In cell activity study, butyric acid inhibited the cell activity irrespective of its concentration. Densitometric analysis showed restriction fragment length polymorphism. These results suggested that there existed heterogeneity of the metabolic acids and the virulence of P. gingivalis and such heterogeneity might be related to genetic heterogeneity.

• The Plant Pathology Journal
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• v.23 no.2
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• pp.62-69
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• 2007

Twenty-nine isolates of Fusarium solani, originally isolated from diseased cotton roots in Egypt, were evaluated for their ability to cause symptoms on four genetically diverse cotton cultivars. Analysis of variance showed highly significant variance among cultivars, and isolates as well as the isolate x genotype interactions were highly significant(p < 0.0001). Although most isolates showed intermediate pathogenicity, there were two groups of isolates that showed significant differences in pathogenicity on all four cultivars. None of the cultivars were found to be immune to any of the isolates. On all cultivars, there were strong significant positive correlations between dry weight and each of preemergence damping-off, survival, and plant height. Considering 75% similarity in virulence, two groups comprising a total of 29 isolates were recognized. Ninety-three percent of the isolates have the same pathogenicity patterns with consistently low pathogenicity, and narrow diversity of virulence. Isolates Fs4 and Fs5 shared the same distinct overall virulence spectrum with consistently high pathogenicity. There was no clear-cut relationship between virulence of the isolates based on reaction pattern on 4 cultivars and each of host genotype, previous crop, and geographic origin.

• The Plant Pathology Journal
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• v.33 no.6
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• pp.602-607
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• 2017

Segregation and condensation protein B (ScpB) is essential for replication and segregation in living organisms. Here, we reported the functions of ScpBXv (ScpB-like protein in Xanthomonas campestris pv. vesicatoria) using phenotypic and proteomic analyses. Growth of $Xcv{\Delta}scpBXv$ (ScpBXv knockout mutant) was reduced under both slow and fast growth conditions in rich medium, but comparable to this of the wild-type in plant-mimic conditions. Interestingly, the mutant was significantly less virulent than the wild-type in tomato, indicating that ScpBXv is involved in virulence. To investigate ScpBXv-associated mechanisms, comparative proteomic analyses were carried out and the abundance of 187 proteins was altered. Among them, diverse transcriptional regulators involved in biofilm formation and virulence were abundant in the wild-type. We further showed that biofilm formation of $Xcv{\Delta}scpBXv$ was reduced. This study provides new insights into the functions of ScpBXv in bacterial replication and biofilm formation, which may contribute to the virulence of Xcv.

• Journal of Microbiology and Biotechnology
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• v.13 no.6
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• pp.1021-1026
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• 2003

Numerous secreted and cell-associated virulence factors have been proposed to account for the fulminating and destructive nature of Vibrio vulnificus infections. Among the putative virulence factors are an elastase, elastolytic protease, and a cytolytic hemolysin. Effects of the elastase on the hemolysin were assessed by evaluating changes of hemolytic activities either in the presence or absence of the protease. Although hemolytic activity in the culture supernatant was lowered by the purified elastase added in vitro, the cellular level of hemolytic activity was unaffected by the mutation of vvpE encoding the elastase. Growth kinetic studies revealed that hemolysin reached its maximum level in the exponential phase of growth, and the elastase appeared at the onset of the stationary phase. These results have provided insight into the regulation of virulence factors: temporally coordinate regulation of virulence factors is essential for the overall success of the pathogen during pathogenesis.

• Food Science and Biotechnology
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• v.16 no.5
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• pp.778-782
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• 2007

This study assessed the effects of the antimicrobial substances sulforaphane, grapefruit seed extracts (GSE), and reuterin on the expression of Salmonella HilA and InvF virulence gene using a LacZY assay (${\beta}$-galactosidase assay) with hilA:lacZY and invF:lacZY fusion strains of Salmonella typhimurium SL1344. Salmonella was grown for 8 hr at $37^{\circ}C$ in the presence of diluted antimicrobial substances ($2\;{\mu}g/mL$ sulforaphane, $20\{\mu}g/mL$ GSE, and 0.26 mM reuterin) at concentrations that did not inhibit the cellular growth of Salmonella. Sulforaphane inhibited the expression of HilA and InvF by 50-90 and 20-80%, respectively. GSE also inhibited the expression of both genes, but to a lesser degree. Among the 3 antimicrobial substances, reuterin showed the least inhibition, which was abolished after 3-4 hr. None of the antimicrobial substances inhibited the ${\beta}$-galactosidase enzyme activity of S. typhimurium. The assay used in this study represents a very sensitive method for screening bioactive substances that inhibit the expression of virulence genes in Salmonella.

• Journal of Microbiology and Biotechnology
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• v.14 no.3
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• pp.515-519
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• 2004

Listeria spp. were isolated from a total of 402 naturally contaminated domestic ready-to-eat (RTE) vegetable samples by the conventional Food and Drug Administration protocol and confinned by API-Listeria kit. Also, the susceptibility to 12 antibiotics, polymerase chain reaction (PCR) assay for virulence gene of pathogenic Listeria monocytogenes isolates, and in vitro virulence assay using myeloma and hybridoma cells from murine and human sources were tested. Among the samples, 17 samples (4.2％) were found to be contaminated with Listeria species. Among the 17 strains of Listeria spp. isolates, only 2 strains (11.8％) of L. monocytogenes and 15 strains (88.2％) of L. innocua were identified. Antibiotic susceptibility test showed that the Listeria spp. isolates were very susceptible to the antibiotics tested, except for nalidixic acid. Among 17 strains of Listeria spp., PCR analysis showed that 2 strains of L. monocytogenes isolates proved to have a virulence hly gene, but none of L. innocua had the hly gene. Also, hybridoma Ped-2E9 cells assay showed that only L. monocytogenes isolates killed approximately 95-99％ hybridoma cells after 6 h, but L. innocua isolates had about 0-5％ lethal effect. These results indicate that PCR assay with hly primer or hybridoma Ped-2E9 cells assay could be used as a good monitoring tool or in vitro virulence test for L. monocytogenes.

• Journal of Microbiology and Biotechnology
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• v.21 no.12
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• pp.1352-1355
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• 2011

Forty-one Enterococcus faecalis (E. faecalis) isolates from feces of pigs and chickens in Korea were screened for the presence of virulence factors. Gelatinase activity (85.4%, 35/41) was the more commonly observed phenotype of virulence in E. faecalis, compared with hemolytic activity (12.2%, 5/41). Thirty-one of 35 (88.6%) gelatinase-positive E. faecalis isolates harbored the gelE and fsrABC genes. A gene encoding for the enterococcal surface protein (Esp) was detected in 24.4% (10/41) of the isolates. All beta-hemolysin-producing isolates harbored the esp gene.

• Biomedical Science Letters
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• v.21 no.4
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• pp.233-240
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• 2015

Some virulence proteins of Helicobacter pylori, such as vacuolating cytotoxic protein A (VacA) and cytotoxin-associated gene protein A (CagA) have been reported to be causative agents of various gastric diseases including chronic gastritis, gastric ulcer or gastric adenocarcinoma. The expression level of these virulence proteins can be regulated when H. pylori is exposed to the antibacterial agent, cyanidin 3-O-glucoside (C3G) as previously reported. In this study, we analyzed the quantitative change of various virulence proteins including CagA and VacA by C3G treatment. We used 2-dimensional electrophoresis (2-DE) to analyze the quantitative change of representative ten proteome components of H. pylori 60190 ($VacA^+/CagA^+$; standard strain of Eastern type). After 2-DE analysis, spot intensities were analyzed using ImageMaster$^{TM}$ 2-DE Platinum software then each spot was identified using matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF-MS) or peptide sequencing using Finnigan LCQ ion trap mass spectrometer (LC-MS/MS). Next, we selected major virulence proteins of H. pylori among quantitatively meaningful ten spots and confirmed the 2-DE results by Western blot analysis. These results suggest that cyanidin 3-O-glucoside can modulate a variety of H. pylori pathogenic determinants.

• Journal of environmental and Sanitary engineering
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• v.15 no.4
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• pp.105-113
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• 2000

We have isolated 65 strains(2.0%) of Y. enterocolitica among 3,219 water samples from 380 spring water sites in Seoul from 1994 to 1999. The biochemical characteristics of isolated strains revealed that TSI was A/A, urea, M.R.($37^{\circ}C$), nitrate, motility($37^{\circ}C$), sorbitol, maltose, manitol, arabinose, mannose, trehalose, xylose were positive(100%) and H$_2$S, arginine, lysine, oxidase, citrate, V.P.($37^{\circ}C$), DNase, motility($37^{\circ}C$), dulcitol, adonitol, lactose and raffinose were negative(100%). In in vitro virulence test, positive rate of AAG and CRMOX were 9.2% and 4.6%, respectively. However in the virulence gene detectable gene detectable test by multiplex-PCR using ail, yst, virF genes, 65 strains were all negative, meaning that Y.enterocolitica strains from domestic spring water were not detected for the virulence. Otherwise, mutiplex-PCR which using ail, yst and subgenus-specific primer pair was the best for identifying the virulence of Y. enterocolitica.