Yersinia enterocolitica biovar 1B is one of a number of strains pathogenic to humans in the genus Yersinia. It has three different type III secretion systems, Ysc, Ysa, and the flagella. In this study, the effect of flagella on biofilm formation was evaluated. In a panel of 31 mutant Y. enterocolitica strains, we observed that mutations that abolish the structure or rotation of the flagella greatly reduce biofilm formation when the bacteria are grown under static conditions. These results were further evaluated by assessing biofilm formation under continuous culture using a flow cell chamber. The results confirmed the important contribution of flagella to the initiation of biofilm production but indicated that there are differences in the progression of biofilm development between static growth and flow conditions. Our results suggest that flagella play a critical role in biofilm formation in Y. enterocolitica.Yersinia enterocolitica is a food-borne, pathogenic, gramnegative bacterium that causes gastroenteritis. In some cases, septicemia can occur, depending on the health of the host. The most serious illnesses are developed by young children under the age of 1 year (1). Y. enterocolitica is one of three humanpathogenic species in the genus Yersinia that, along with Yersinia pseudotuberculosis, causes gastroenteritis. The third species, Yersinia pestis, is the causative agent of plague. Historically, the formation of biofilms by Y. pestis has been better studied than biofilms of the other two. It has been suggested that Y. pestis biofilms induce starvation of fleas by blocking their digestive tracts. These biofilms seem to affect the fleas but play no role in mammalian pathogenesis, as Y. pestis strains unable to form biofilms are still able to be transmitted by fleas and cause disease (23-25, 53).There are many studies showing the importance of flagella in biofilm formation in other bacteria (32,61,67). In Escherichia coli, a screen showed that 34 of 72 adhesion-deficient strains had changes in motility characteristics (31). Another screen showed that about half the strains that were biofilm defective also exhibited changes in motility function (67), and while motility was a critical factor under certain biofilm formation conditions, chemotaxis was not required (67). Flagella are involved in the adherence of enteropathogenic E. coli to epithelial cells (32), and flagella are also important for biofilm development in Pseudomonas aeruginosa and Aeromonas spp. (61). However, there are other studies that suggest that flagella are not essential for biofilm formation in E. coli (68), P. aeruginosa (47), and Pseudomonas fluorescens (74). These studies suggest that the critical contribution of flagella to biofilm formation is conditional.Among the three pathogenic Yersinia strains, only Y. enterocolitica and Y. pseudotuberculosis are motile. Y. pestis has a frameshift in flhD, the flagellar-biosynthesis regulator protein, and is therefore nonmotile. The goal of this study was to determine whether flagella and motility...
Biofilm provides a bacterial hiding place by forming a physical barrier and causing physiological changes in cells. The elimination of biofilm is the main goal of hygiene. Chemicals that are inhibitory to biofilm formation have been developed for use in food, personal hygiene products, and medical instruments. Monoacylglycerols are recognized as safe and are used in food as emulsifiers. In this study, the inhibitory activity of monoacylglycerols on bacterial biofilm formation was evaluated systematically with four bacterial strains, Aeromonas hydrophila, Streptococcus mutans, Xanthomonas oryzae, and Yersinia enterocolitica. Monoacylglycerols with two specific lengths of fatty acid moiety, monolaurin and monobehenin, were found to have strong inhibitory activity toward bacterial biofilm formation of S. mutans, X. oryzae, and Y. enterocolitica in a strain specific manner. First, this result suggested that biofilm formation was not inhibited by the detergent characteristics of monoacylglycerols. This suggestion was supported by the inhibitory action of monolaurin on biofilm development but not on the initial cell attachment of Y. enterocolitica in flow cytometric observation. Second, it was also suggested that two distinct response mechanisms to monoacylglycerols existed in bacteria. The existence of these two inhibitory response mechanisms was bacterial strain specific.Electronic supplementary materialThe online version of this article (doi:10.1186/s40064-016-3182-5) contains supplementary material, which is available to authorized users.
ABSTRACT. Lawsonia intracellularis (L. intracellularis) was isolated from a Korean pig suffering acute proliferative enteropathy. Proliferative enteropathy (PE) is an enteric disease of pigs caused by the obligate intracellular bacterium, Lawsonia intracellularis (L. intracellularis) [11,13]. It is estimated that about 30% of pig herds suffer from clinical or sub-clinical PE [9]. A study in Korea indicated that 53% of finisher pigs in the disease-harboring farms were infected with L. intracellularis [8]. Since L. intracellularis is a fastidious bacterium for pure culturing in vitro, its isolation and culturing has been achieved in only a few laboratories [6,7]. In this study, we report the isolation of L. intracellularis for the first time in Korea and the reproduction of PE in pigs and hamsters that were infected with the pure culture of L. intracellularis.A hemorrhagic region of the small intestine was obtained from a 20-week-old finisher pig in Korea that showed typical signs of acute hemorrhagic PE [3,13]. Isolation of L. intracellularis was performed by the previously reported methods with some modifications [6,13]. Briefly, the mucosa taken from the PE lesion of the small intestine was partially digested with 1% trypsin (Gibco BRL, U.S.A.) and homogenized with a blender. The homogenized tissue was diluted 1:20 vol/vol with sucrose-potassium-glutamate solution (pH 7.0) containing 0.218 M sucrose, 0.0038 M KH 2 PO 4 , 0.0049 M potassium glutamate and 10% fetal bovine serum (FBS), and then filtered through 0.8-µm-pore sized filter. One milliliter of the sample suspension was added to McCoy cells (ATCC CRL 1696) grown in DMEM medium supplemented with 1% L-glutamine, 2.5 µg/ml amphotericin B and 5% FBS without antibiotics. The cellcontaining flasks were immediately centrifuged at 2,090 × g for 10 min and the atmosphere of the flasks was replaced with hydrogen gas for 10 min. Each flask was then refilled with a gas mixture containing 8.0% oxygen, 8.8% carbon dioxide, and 83.2% nitrogen as described elsewhere [7]. After 3-hr incubation at 37°C, the culture medium of the flask was changed with DMEM containing 100 µ/ml of gentamicin and 100 µg/ml vancomycin. The cell culture medium was changed at days 2 and 4 post-inoculation. On day 7, L. intracellularis was harvested from the McCoy cells by lysis with hypotonic solution as described elsewhere [7]. After five passages in the McCoy cells, L. intracellularis present in the cytoplasm of the cells was identified by immunostaining with monoclonal antibodies IG4 and 2001 MAb [2, 10]. Six 3-week-old pigs were used in this study. They all tested negative for Brachyspira species and L. intracellularis as determined by serologic tests and PCR [1,5]. Three of them were orally infected with 4.5 × 108 L. intracellularis that had been purified from the bacteriainfected McCoy cells after nine passages. The other three pigs were used as non-infected controls. In addition, eight 4-week-old Syrian hamsters (Mesocricetus auratus) were used in this study, all of which were negative ...
The aim of this study was to examine a single-nucleotide polymorphism (SNP) rs7639618 of double von Willebrand factor (DVWA) gene for the association with osteoarthritis (OA) susceptibility in Korean cohort. The study was a part of the Korean cohort study. Two thousand four hundred sixty-two subjects aged 50 years and older who were derived from the cohort and who were assessed for OA at the knee were genotyped. The anteroposterior extended-view weight-bearing radiographs of the knees were obtained. Of the subjects, 725 subjects had radiographic OA. Genomic DNA was extracted from peripheral blood using a QIAamp DNA Blood Mini Kit (Qiagen, Valencia, CA). Genotyping was performed using High Resolution Melt or the Taq-Man allelic discrimination assay and the Rotor-Gene 6000 (Corbett Research, Sydney,Australia). Associations were tested by calculating the odds ratios (ORs) and 95% confidence intervals (95% CIs), using logistic regression analysis with adjustments for age, gender, and body mass index (BMI). The mean age of the OA patients (females: 554 subjects, 76.4%) was 67.4 (7.9) years. The intraobserver agreement was high for the identification of osteophytes (κ: 0.80) and joint space narrowing (κ: 0.70). There was no significant difference (all P values > 0.05) in the genotype or allele frequencies between the patients with OA and healthy controls. There was also no significant difference when the cases were adjusted by age, gender, and BMI. The associations of DVWA SNPs with OA were noted in previous studies and were not found in the Korean OA cohort.
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