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Turgeon, Nathalie

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Université Laval
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Voici les éléments 1 - 10 sur 13
  • Publication
    Role of galK and galM in galactose metabolism by Streptococcus thermophilus
    (American Society for Microbiology, 2008-02-07) Vadeboncoeur, Christian; Frenette, Michel; Moineau, Sylvain; Vaillancourt, Katy; Robitaille, Gilles; Turgeon, Nathalie; Bédard, Nathalie; Bart, Christian
    Streptococcus thermophilus is unable to metabolize the galactose moiety of lactose. In this paper, we show that a transformant of S. thermophilus SMQ-301 expressing Streptococcus salivarius galK and galM was able to grow on galactose and expelled at least twofold less galactose into the medium during growth on lactose.
  • Publication
    Accès libre
    Evaluation of the plasmid copy number in B. cereus spores, during germination, bacterial growth and sporulation using real-time PCR
    (Elsevier, 2008-09-01) Duchaine, Caroline; Turgeon, Nathalie; Ho, Jim; Laflamme, Christian.
    Only a small number of studies have measured the plasmid copy number (PCN) variation during bacterial growth. Besides, information about the PCN in spores is still rare. In this work, we utilized a real-time PCR assay to evaluate the PCN of four different plasmids in Bacillus cereus. The PCN was measured in spores as well as during germination, active bacterial growth, and sporulation. Plasmid stability was also evaluated to ensure that plasmid loss does not affect the accuracy of the PCN measurement. We demonstrated that the PCN of low and high copy number plasmids varies with growth phase as well as culture media over B. cereus life cycle. The PCN was minimum during the germination and maximum during the stationary growth phase for all plasmids tested. We also demonstrated that the use of antibiotic in the culture media is not enough to ensure stable inheritance in spores of plasmids carrying antibiotic resistance genes. Moreover, we revealed that the PCN in spores is related to the PCN during endospores formation. Therefore, the plasmid partitioning during sporulation is not influenced by the unequal-size of the forespores and the mother cells, even for a plasmid distributed randomly.
  • Publication
    Accès libre
    Elaboration of an electroporation protocol for Bacillus cereus ATCC 14579
    (Elsevier Biomedical, 2006-07-03) Duchaine, Caroline; Turgeon, Nathalie; Ho, Jim; Laflamme, Christian.
    An electro-transformation procedure was established for Bacillus cereus ATCC 14579. Using early growth-stage culture and high electric field, the ectroporation efficiency was up to 2 x 10(9) cfu microg(-1) ml(-1) with pC194 plasmid DNA. The procedure was tested with three other plasmids, of various sizes, replication mechanisms and selection markers, and the transformation efficiencies ranged between 2 x 10(6) and 1 x 10(8) cfu microg(-1) ml(-)(1). The effects of two wall-weakening agents on electroporation rates were also evaluated. The transformation rate that was reached with our procedure is 10(3) times higher than that previously obtained with members of the Bacillus genus with similar plasmids, and 10(6) times superior than that achieved with available protocols for B. cereus. The proposed method is quick, simple, efficient with small rolling circle plasmids and large theta replicating plasmids with low copy number per cell, and suitable for many genetic manipulations that are not possible without high-efficiency transformation protocols.
  • Publication
    Accès libre
    Comparison of five bacteriophages as models for viral aerosol studies
    (American Society for Microbiology, 2014-04-29) Duchaine, Caroline; Toulouse, Marie-Josée; Moineau, Sylvain; Martel, Bruno; Turgeon, Nathalie
    Bacteriophages are perceived to be good models for the study of airborne viruses because they are safe to use, some of them display structural features similar to those of human and animal viruses, and they are relatively easy to produce in large quantities. Yet, only a few studies have investigated them as models. It has previously been demonstrated that aerosolization, environmental conditions, and sampling conditions affect viral infectivity, but viral infectivity is virus dependent. Thus, several virus models are likely needed to study their general behavior in aerosols. The aim of this study was to compare the effects of aerosolization and sampling on the infectivity of five tail-less bacteriophages and two pathogenic viruses: MS2 (a single-stranded RNA [ssRNA] phage of the Leviviridae family), F6 (a segmented double-stranded RNA [dsRNA] phage of the Cystoviridae family), FX174 (a single-stranded DNA [ssDNA] phage of the Microviridae family), PM2 (a double-stranded DNA [dsDNA] phage of the Corticoviridae family), PR772 (a dsDNA phage of the Tectiviridae family), human influenza A virus H1N1 (an ssRNA virus of the Orthomyxoviridae family), and the poultry virus Newcastle disease virus (NDV; an ssRNA virus of the Paramyxoviridae family). Three nebulizers and two nebulization salt buffers (with or without organic fluid) were tested, as were two aerosol sampling devices, a liquid cyclone (SKC BioSampler) and a dry cyclone (National Institute for Occupational Safety and Health two-stage cyclone bioaerosol sampler). The presence of viruses in collected air samples was detected by culture and quantitative PCR (qPCR). Our results showed that these selected five phages behave differently when aerosolized and sampled. RNA phage MS2 and ssDNA phage FX174 were the most resistant to aerosolization and sampling. The presence of organic fluid in the nebulization buffer protected phages PR772 and F6 throughout the aerosolization and sampling with dry cyclones. In this experimental setup, the behavior of the influenza virus resembled that of phages PR772 and F6, while the behavior of NDV was closer to that of phages MS2 and FX174. These results provide critical information for the selection of appropriate phage models to mimic the behavior of specific human and animal viruses in aerosols.
  • Publication
    Accès libre
    Neuraminidase activity as a potential enzymatic marker for rapid detection of airborne viruses
    (Elsevier, 2011-10-24) Duchaine, Caroline; McNicoll, François; Toulouse, Marie-Josée; Turgeon, Nathalie; Liav, Avraham; Barbeau, Jean; Jim, Ho; Grund, Christian
    Viruses offer a limited range of targets for their detection. To date, PCR and RT-PCR have been widely used for detection of viruses. In the case of environmental air sampling, the ability to detect a broad range of viruses would constitute a significant advantage for preventing outbreaks of airborne-transmitted viral infections. Given that neuraminidase is found on some respiratory virus species of medical or agricultural importance, this enzyme could theoretically be used to detect several different airborne viruses in a single assay. The aim of the present study was to evaluate the potential of neuraminidase activity as a marker for rapid detection of airborne viruses. We first validated the use of a low-pathogenic strain of Newcastle disease virus (NDV) as a model airborne virus. Our findings revealed that neuraminidase activity-based assays are almost as sensitive as RT-PCR assays currently used for detection of NDV. We also validated the utilization of a neuraminidase substrate specific to viral neuraminidase. Experiments conducted in a controlled chamber demonstrated that the neuraminidase activity is preserved after aerosolization, air sampling using impingement and handling. Finally, we tested our method with swine barn air samples. Our results demonstrate that neuraminidase activity-based assays are suitable for detection of viruses in air samples.
  • Publication
    Accès libre
    Impact of serotype and sequence type on the preferential aerosolization of Streptococcus suis
    (Biomed Central, 2016-05-14) Duchaine, Caroline; Veillette, Marc; Perrott, Phillipa; Grenier, Daniel; Turgeon, Nathalie; Bonifait, Laetitia; Gauthier-Levesque, Léa
    Streptococcus suis is a swine pathogen that causes pneumonia, septicaemia and meningitis. It is also an important zoonotic agent responsible of several outbreaks in China. S. suis strains are classified into 35 serotypes based on the composition of their polysaccharide capsule. S. suis serotype 2 causes the majority of severe infections and it is subdivided into sequence types (STs) based on multilocus sequence typing. The ST1 is associated with highly virulent strains. In North America, the strains most commonly isolated belong to ST25 and ST28, which are respectively moderately and weakly virulent in a mouse model. The presence of S. suis bioaerosols in the air of swine confinement buildings has been previously demonstrated. The aim of this study was to better understand the aerosolization behaviour of S. suis by investigating of the preferential aerosolization of different strains of S. suis. The highly virulent serotype 2 ST1 strains appeared to be preferentially aerosolized. This study increases our knowledge on the potential aerosol transmission of S. suis and emphasises the importance of developing an exposure prevention strategy to protect the swine and the swine producers.
  • Publication
    Accès libre
    Resistance of aerosolized bacterial viruses to relative humidity and temperature
    (American Society for Microbiology, 2015-10-01) Duchaine, Caroline; Marcoux-Voiselle, Mélissa; Moineau, Sylvain; Verreault, Daniel; Turgeon, Nathalie
    The use of aerosolized bacteriophages as surrogates to hazardous viruses could simplify and accelerate the discovery of links between viral components and their persistence in the airborne state under diverse environmental conditions. In this study, four structurally distinct lytic phages, MS2 (ssRNA), F6 (dsRNA), FX174 (ssDNA) and PR772 (dsDNA), were nebulised into a rotating chamber and exposed to various levels of relative humidity (RH) and temperature as well as to germicidal ultraviolet radiations. The aerosolized viral particles were allowed to remain airborne for up to fourteen hours before being sampled for analysis by plaque assays and quantitative PCR. Phages F6 and MS2 were most resistant at low levels of relative humidity whilst FX174 was more resistant at 80% RH. Phage F6 lost its infectivity immediately after exposure to 30°C and 80% RH. The infectivity of all tested phages rapidly declined as a function of the exposure time to UV-C radiations, phage MS2 being the most resistant. Taken altogether, our data indicate that these aerosolized phages behave differently under various environmental conditions and highlight the necessity of carefully selecting viral simulants in bioaerosols studies.
  • Publication
    Accès libre
    Detection and quantification of airborne norovirus during outbreaks in healthcare facilities
    (Oxford University Press, 2015-04-21) Bonifait, Laetitia; Charlebois, Rémi; Vimont, Allison; Turgeon, Nathalie; Veillette, Marc; Longtin, Yves; Jean, Julie; Duchaine, Caroline
    Background. Noroviruses are responsible for at least 50% of all gastroenteritis outbreaks worldwide. Noroviruses GII can infect humans via multiple routes including direct contact with an infected person, fecal matter, or vomitus, and contact with contaminated surfaces. Although norovirus is an intestinal pathogen, aerosols could, if inhaled, settle in the pharynx and later be swallowed. The aims of this study were to investigate the presence of norovirus GII bioaerosols during gastroenteritis outbreaks in healthcare facilities and to study the in vitro effects of aerosolization and air sampling on the noroviruses using murine norovirus as a surrogate. Methods. A total of 48 air samples were collected during norovirus outbreaks in 8 healthcare facilities. Samples were taken 1 m away from each patient, in front of the patient's room and at the nurses' station. The resistance to aerosolization stress of murine norovirus type 1 (MNV-1) bioaerosols was also tested in vitro using an aerosol chamber. Results. Norovirus genomes were detected in 6 of 8 healthcare centers. The concentrations ranged from 1.35 × 101 to 2.35 × 103 genomes/m3 in 47% of air samples. MNV-1 preserved its infectivity and integrity during in vitro aerosol studies. Conclusions. Norovirus genomes are frequently detected in the air of healthcare facilities during outbreaks, even outside patients' rooms. In addition, in vitro models suggest that this virus may withstand aerosolization.
  • Publication
    A simple and rapid fluorescent neuraminidase enzymatic assay on a microfluidic chip
    (Elsevier Science, 2012-09-15) Zhang, Fang; Duchaine, Caroline; Toulouse, Marie-Josée; Turgeon, Nathalie; Li, Dongqing
    Neuraminidase enzymatic assay is an inexpensive, reliable, and quick method of detecting viruses. However, the assay in conventional laboratories requires a large amount of samples and reagents and multiple steps, which makes the conventional assay labor intensive and time consuming. This article reports a novel and simple method for conducting the neuraminidase enzymatic assay on a microfluidic chip. By using 4-methylumbelliferyl-N-acetyl-a-d-neuraminic acid as the fluorescent substrate and applying an electric field, the newly developed assay is simple, fast, and automatic. Fluorescence of the enzymatic reaction product was recorded as the assay result, and the fluorescence intensity quantitatively indicates the concentration of the sample, which proves that the novel assay on a microfluidic chip has a potential to be developed into a portable device for on-site detection of environmental samples.
  • Publication
    Design of an environmentally controlled rotating chamber for bioaerosol aging studies
    (Hemisphere Pub. Corp., 2014-07-15) Duchaine, Caroline; Marcoux-Voiselle, Mélissa; Verreault, Daniel; Marcoux-Voiselle, Marcoux-Voiselle; Turgeon, Nathalie; J. Roy, Chad
    A chamber was designed and built to study the long-term effects of environmental conditions on air-borne microorganisms. The system consists of a 55.5-L cylindrical chamber, which can rotate at variable speeds on its axis. The chamber is placed within an insulated temperature controlled enclosure which can be either cooled or heated with piezoelectric units. A germicidal light located at the chamber center irradiates at a 360° angle. Access ports are located on the stationary sections on both ends of the chamber. Relative humidity (RH) is controlled by passing the aerosol through meshed tubes surrounded by desiccant. Validation assay indicates that the interior temperature is stable with less than 0.5 °C in variation when set between 18 and 30 °C with the UV light having no effect of temperature during operation. RH levels set at 20%, 50% and 80% varied by 2.2%, 3.3% and 3.3%, respectively, over a 14-h period. The remaining fraction of particles after 18 h of suspension was 8.8% at 1 rotation per minute (rpm) and 2.6% at 0 rpm with the mass median aerodynamic diameter (MMAD) changing from 1.21 ± 0.04 µm to 1.30 ± 0.02 µm at 1 rpm and from 1.21 ± 0.04 µm to 0.91 ± 0.01 µm at 0 rpm within the same time period. This chamber can be used to increase the time of particle suspension in an aerosol cloud and control the temperature, RH and UV exposure; the design facilitates stationary sampling to be performed while the chamber is rotating.