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Sylvestre É, Dorner S, Burnet JB, Smeets P, Medema G, Cantin P, Villion M, Robert C, Ellis D, Servais P, Prévost M. Changes in Escherichia coli to enteric protozoa ratios in rivers: Implications for risk-based assessment of drinking water treatment requirements. Water Res 2021; 205:117707. [PMID: 34619609 DOI: 10.1016/j.watres.2021.117707] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Revised: 09/11/2021] [Accepted: 09/22/2021] [Indexed: 06/13/2023]
Abstract
Minimum treatment requirements are set in response to established or anticipated levels of enteric pathogens in the source water of drinking water treatment plants (DWTPs). For surface water, contamination can be determined directly by monitoring reference pathogens or indirectly by measuring fecal indicators such as Escherichia coli (E. coli). In the latter case, a quantitative interpretation of E. coli for estimating reference pathogen concentrations could be used to define treatment requirements. This study presents the statistical analysis of paired E. coli and reference protozoa (Cryptosporidium, Giardia) data collected monthly for two years in source water from 27 DWTPs supplied by rivers in Canada. E. coli/Cryptosporidium and E. coli/Giardia ratios in source water were modeled as the ratio of two correlated lognormal variables. To evaluate the potential of E. coli for defining protozoa treatment requirements, risk-based critical mean protozoa concentrations in source water were determined with a reverse quantitative microbial risk assessment (QMRA) model. Model assumptions were selected to be consistent with the World Health Organization (WHO) Guidelines for drinking-water quality. The sensitivity of mean E. coli concentration trigger levels to identify these critical concentrations in source water was then evaluated. Results showed no proportionalities between the log of mean E. coli concentrations and the log of mean protozoa concentrations. E. coli/protozoa ratios at DWTPs supplied by small rivers in agricultural and forested areas were typically 1.0 to 2.0-log lower than at DWTPs supplied by large rivers in urban areas. The seasonal variations analysis revealed that these differences were related to low mean E. coli concentrations during winter in small rivers. To achieve the WHO target of 10-6 disability-adjusted life year (DALY) per person per year, a minimum reduction of 4.0-log of Cryptosporidium would be required for 20 DWTPs, and a minimum reduction of 4.0-log of Giardia would be needed for all DWTPs. A mean E. coli trigger level of 50 CFU 100 mL-1 would be a sensitive threshold to identify critical mean concentrations for Cryptosporidium but not for Giardia. Treatment requirements higher than 3.0-log would be needed at DWTPs with mean E. coli concentrations as low as 30 CFU 100 mL-1 for Cryptosporidium and 3 CFU 100 mL-1 for Giardia. Therefore, an E. coli trigger level would have limited value for defining health-based treatment requirements for protozoa at DWTPs supplied by small rivers in rural areas.
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Affiliation(s)
- Émile Sylvestre
- NSERC Industrial Chair on Drinking Water, Department of Civil, Geological, and Mining Engineering, Polytechnique Montreal, Montreal, Quebec H3C 3A7, Canada; Canada Research Chair in Source Water Protection, Department of Civil, Geological, and Mining Engineering, Polytechnique Montreal, Montreal, Quebec H3C 3A7, Canada.
| | - Sarah Dorner
- Canada Research Chair in Source Water Protection, Department of Civil, Geological, and Mining Engineering, Polytechnique Montreal, Montreal, Quebec H3C 3A7, Canada
| | - Jean-Baptiste Burnet
- NSERC Industrial Chair on Drinking Water, Department of Civil, Geological, and Mining Engineering, Polytechnique Montreal, Montreal, Quebec H3C 3A7, Canada; Canada Research Chair in Source Water Protection, Department of Civil, Geological, and Mining Engineering, Polytechnique Montreal, Montreal, Quebec H3C 3A7, Canada
| | - Patrick Smeets
- KWR Water Research Institute, Groningenhaven 7, 3433 PE Nieuwegein, The Netherlands
| | - Gertjan Medema
- KWR Water Research Institute, Groningenhaven 7, 3433 PE Nieuwegein, The Netherlands; Sanitary Engineering, Department of Water Management, Faculty of Civil Engineering and Geosciences, Delft University of Technology, P.O. Box 5048, 2600GA Delft, The Netherlands
| | - Philippe Cantin
- Ministère de l'Environnement et de la Lutte contre les changements climatiques, Québec, Canada
| | - Manuela Villion
- Centre d'expertise en analyse environnementale du Québec, Ministère de l'Environnement et de la Lutte contre les changements climatiques, Québec, Canada
| | - Caroline Robert
- Ministère de l'Environnement et de la Lutte contre les changements climatiques, Québec, Canada
| | - Donald Ellis
- Ministère de l'Environnement et de la Lutte contre les changements climatiques, Québec, Canada
| | - Pierre Servais
- Ecology of Aquatic Systems, Université libre de Bruxelles, Brussels, Belgium
| | - Michèle Prévost
- NSERC Industrial Chair on Drinking Water, Department of Civil, Geological, and Mining Engineering, Polytechnique Montreal, Montreal, Quebec H3C 3A7, Canada
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Sylvestre É, Prévost M, Smeets P, Medema G, Burnet JB, Cantin P, Villion M, Robert C, Dorner S. Importance of Distributional Forms for the Assessment of Protozoan Pathogens Concentrations in Drinking-Water Sources. Risk Anal 2021; 41:1396-1412. [PMID: 33103818 DOI: 10.1111/risa.13613] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Revised: 09/18/2020] [Accepted: 10/02/2020] [Indexed: 06/11/2023]
Abstract
The identification of appropriately conservative statistical distributions is needed to predict microbial peak events in drinking water sources explicitly. In this study, Poisson and mixed Poisson distributions with different upper tail behaviors were used for modeling source water Cryptosporidium and Giardia data from 30 drinking water treatment plants. Small differences (<0.5-log) were found between the "best" estimates of the mean Cryptosporidium and Giardia concentrations with the Poisson-gamma and Poisson-log-normal models. However, the upper bound of the 95% credibility interval on the mean Cryptosporidium concentrations of the Poisson-log-normal model was considerably higher (>0.5-log) than that of the Poisson-gamma model at four sites. The improper choice of a model may, therefore, mislead the assessment of treatment requirements and health risks associated with the water supply. Discrimination between models using the marginal deviance information criterion (mDIC) was unachievable because differences in upper tail behaviors were not well characterized with available data sets ( n<30 ). Therefore, the gamma and the log-normal distributions fit the data equally well but may predict different risk estimates when they are used as an input distribution in an exposure assessment. The collection of event-based monitoring data and the modeling of larger routine monitoring data sets are recommended to identify appropriately conservative distributions to predict microbial peak events.
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Affiliation(s)
- Émile Sylvestre
- NSERC Industrial Chair on Drinking Water, Department of Civil, Geological, and Mining Engineering, Polytechnique Montreal, Montreal, Quebec, H3C 3A7, Canada
- Canada Research Chair in Source Water Protection, Department of Civil, Geological, and Mining Engineering, Polytechnique Montreal, Montreal, Quebec, H3C 3A7, Canada
| | - Michèle Prévost
- NSERC Industrial Chair on Drinking Water, Department of Civil, Geological, and Mining Engineering, Polytechnique Montreal, Montreal, Quebec, H3C 3A7, Canada
| | - Patrick Smeets
- KWR Water Research Institute, Groningenhaven 7, Nieuwegein, 3433 PE, The Netherlands
| | - Gertjan Medema
- KWR Water Research Institute, Groningenhaven 7, Nieuwegein, 3433 PE, The Netherlands
- Sanitary Engineering, Department of Water Management, Faculty of Civil Engineering and Geosciences, Delft University of Technology, P.O. Box 5048, Delft, 2600GA, The Netherlands
| | - Jean-Baptiste Burnet
- NSERC Industrial Chair on Drinking Water, Department of Civil, Geological, and Mining Engineering, Polytechnique Montreal, Montreal, Quebec, H3C 3A7, Canada
- Canada Research Chair in Source Water Protection, Department of Civil, Geological, and Mining Engineering, Polytechnique Montreal, Montreal, Quebec, H3C 3A7, Canada
| | - Philippe Cantin
- Ministère de l'Environnement et de la Lutte contre les changements climatiques, Québec, Canada
| | - Manuela Villion
- Centre d'expertise en analyse environnementale du Québec, Ministère de l'Environnement et de la Lutte contre les changements climatiques, Québec, Canada
| | - Caroline Robert
- Ministère de l'Environnement et de la Lutte contre les changements climatiques, Québec, Canada
| | - Sarah Dorner
- Canada Research Chair in Source Water Protection, Department of Civil, Geological, and Mining Engineering, Polytechnique Montreal, Montreal, Quebec, H3C 3A7, Canada
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Sylvestre É, Burnet JB, Dorner S, Smeets P, Medema G, Villion M, Hachad M, Prévost M. Impact of Hydrometeorological Events for the Selection of Parametric Models for Protozoan Pathogens in Drinking-Water Sources. Risk Anal 2021; 41:1413-1426. [PMID: 33103797 DOI: 10.1111/risa.13612] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Revised: 07/07/2020] [Accepted: 07/10/2020] [Indexed: 06/11/2023]
Abstract
Temporal variations in concentrations of pathogenic microorganisms in surface waters are well known to be influenced by hydrometeorological events. Reasonable methods for accounting for microbial peaks in the quantification of drinking water treatment requirements need to be addressed. Here, we applied a novel method for data collection and model validation to explicitly account for weather events (rainfall, snowmelt) when concentrations of pathogens are estimated in source water. Online in situ β-d-glucuronidase activity measurements were used to trigger sequential grab sampling of source water to quantify Cryptosporidium and Giardia concentrations during rainfall and snowmelt events at an urban and an agricultural drinking water treatment plant in Quebec, Canada. We then evaluate if mixed Poisson distributions fitted to monthly sampling data ( n = 30 samples) could accurately predict daily mean concentrations during these events. We found that using the gamma distribution underestimated high Cryptosporidium and Giardia concentrations measured with routine or event-based monitoring. However, the log-normal distribution accurately predicted these high concentrations. The selection of a log-normal distribution in preference to a gamma distribution increased the annual mean concentration by less than 0.1-log but increased the upper bound of the 95% credibility interval on the annual mean by about 0.5-log. Therefore, considering parametric uncertainty in an exposure assessment is essential to account for microbial peaks in risk assessment.
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Affiliation(s)
- Émile Sylvestre
- NSERC Industrial Chair on Drinking Water, Department of Civil, Geological, and Mining Engineering, Polytechnique Montreal, Montreal, Quebec, H3C 3A7, Canada
- Canada Research Chair in Source Water Protection, Department of Civil, Geological, and Mining Engineering, Polytechnique Montreal, Montreal, Quebec, H3C 3A7, Canada
| | - Jean-Baptiste Burnet
- NSERC Industrial Chair on Drinking Water, Department of Civil, Geological, and Mining Engineering, Polytechnique Montreal, Montreal, Quebec, H3C 3A7, Canada
- Canada Research Chair in Source Water Protection, Department of Civil, Geological, and Mining Engineering, Polytechnique Montreal, Montreal, Quebec, H3C 3A7, Canada
| | - Sarah Dorner
- Canada Research Chair in Source Water Protection, Department of Civil, Geological, and Mining Engineering, Polytechnique Montreal, Montreal, Quebec, H3C 3A7, Canada
| | - Patrick Smeets
- KWR Water Research Institute, Groningenhaven 7, Nieuwegein, 3433 PE, The Netherlands
| | - Gertjan Medema
- KWR Water Research Institute, Groningenhaven 7, Nieuwegein, 3433 PE, The Netherlands
- Sanitary Engineering, Department of Water Management, Faculty of Civil Engineering and Geosciences, Delft University of Technology, P.O. Box 5048, Delft, 2600GA, The Netherlands
| | - Manuela Villion
- Centre d'expertise en analyse environnementale du Québec, Ministère de l'Environnement et de la Lutte contre les changements climatiques, Québec, Canada
| | - Mounia Hachad
- NSERC Industrial Chair on Drinking Water, Department of Civil, Geological, and Mining Engineering, Polytechnique Montreal, Montreal, Quebec, H3C 3A7, Canada
- Canada Research Chair in Source Water Protection, Department of Civil, Geological, and Mining Engineering, Polytechnique Montreal, Montreal, Quebec, H3C 3A7, Canada
| | - Michèle Prévost
- NSERC Industrial Chair on Drinking Water, Department of Civil, Geological, and Mining Engineering, Polytechnique Montreal, Montreal, Quebec, H3C 3A7, Canada
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Bédard E, Paranjape K, Lalancette C, Villion M, Quach C, Laferrière C, Faucher SP, Prévost M. Legionella pneumophila levels and sequence-type distribution in hospital hot water samples from faucets to connecting pipes. Water Res 2019; 156:277-286. [PMID: 30925374 DOI: 10.1016/j.watres.2019.03.019] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 03/08/2019] [Accepted: 03/14/2019] [Indexed: 05/07/2023]
Abstract
Recent studies have reported increased levels of Legionella pneumophila (Lp) at points of use compared to levels in primary and secondary components of hot water systems, suggesting possible selection by environmental conditions. In this study, concentrations of Lp in a hospital hot water system were evaluated by profile sampling, collecting successive water samples to determine the prevalence at the faucet (distal) and upstream piping before and after a system intervention to increase temperature. Lp strain diversity was compared between different points of use and different areas of the hot water system (i.e., tap, intermediate piping and main upflow piping). In total, 47 isolates were recovered from 32 positive hot water samples collected from designated taps, showers and recirculation loops; these isolates were subsequently analyzed by sequence-based typing (SBT). Lp levels were comparable between first draw (500 mL) and flushed (2 and 5 min) samples, whereas a decrease was observed in the amount of culturable cells (1 log). Two sequence types (STs) were identified throughout the system. ST378 (sg4/10) was present in 91% of samples, while ST154-like (sg1) was present in 41%; both STs were simultaneously recovered in 34% of samples. Isolated STs displayed comparable tolerance to copper (0.8-5 mg/L) and temperature (55 °C, 1 h) exposure. The ability to replicate within THP1 cells and Acanthamoeba castellanii was similar between the two STs and a comparative environmental outbreak strain. The low Lp diversity and the detection of both Lp sequence types in repeated subsequent samples collected from positive faucets in a hospital wing suggest a minimal impact of the distal conditions on strain selection for the sampled points, as well as a possible adaptation to stressors present in the system, leading to the predominance of a few strains.
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Affiliation(s)
- Emilie Bédard
- Department of Civil Engineering, Polytechnique Montréal, Montréal, QC, Canada; Department of Natural Resource Sciences, Faculty of Agricultural and Environmental Sciences, McGill University, Sainte-Anne-de-Bellevue, QC, Canada.
| | - Kiran Paranjape
- Department of Natural Resource Sciences, Faculty of Agricultural and Environmental Sciences, McGill University, Sainte-Anne-de-Bellevue, QC, Canada
| | - Cindy Lalancette
- Laboratoire de santé publique du Québec, Sainte-Anne-de-Bellevue, QC, Canada
| | - Manuela Villion
- Centre d'expertise en analyse environnementale du Québec, Ministère de l'Environnement et de la Lutte contre les changements climatiques, Québec, Canada
| | - Caroline Quach
- Department of Microbiology, Infectiology and Immunology, Université de Montréal, Montréal, QC, Canada
| | - Céline Laferrière
- Department of Microbiology, Infectiology and Immunology, Université de Montréal, Montréal, QC, Canada
| | - Sebastien P Faucher
- Department of Natural Resource Sciences, Faculty of Agricultural and Environmental Sciences, McGill University, Sainte-Anne-de-Bellevue, QC, Canada
| | - Michèle Prévost
- Department of Civil Engineering, Polytechnique Montréal, Montréal, QC, Canada
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5
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Hynes AP, Villion M, Moineau S. Adaptation in bacterial CRISPR-Cas immunity can be driven by defective phages. Nat Commun 2014; 5:4399. [DOI: 10.1038/ncomms5399] [Citation(s) in RCA: 104] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Accepted: 06/13/2014] [Indexed: 12/21/2022] Open
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6
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Campagna C, Villion M, Labrie SJ, Duchaine C, Moineau S. Inactivation of dairy bacteriophages by commercial sanitizers and disinfectants. Int J Food Microbiol 2014; 171:41-7. [DOI: 10.1016/j.ijfoodmicro.2013.11.012] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Revised: 11/01/2013] [Accepted: 11/11/2013] [Indexed: 01/14/2023]
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Dupuis MÈ, Villion M, Magadán AH, Moineau S. CRISPR-Cas and restriction–modification systems are compatible and increase phage resistance. Nat Commun 2013; 4:2087. [DOI: 10.1038/ncomms3087] [Citation(s) in RCA: 157] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2013] [Accepted: 05/30/2013] [Indexed: 12/24/2022] Open
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Abstract
A recent paper gives the details on how specific small RNAs can program a protein to cleave an undesired piece of DNA and to provide immunity to a microbial cell.
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Affiliation(s)
- Manuela Villion
- Département de Biochimie, de Microbiologie et de Bio-informatique, Faculté des Sciences et de Génie, Groupe de Recherche en Écologie Buccale, Faculté de Médecine Dentaire, Félix d'Hérelle Reference Center for Bacterial Viruses, Université Laval, Québec City, Quebec G1V 0A6, Canada
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Magadán AH, Dupuis MÈ, Villion M, Moineau S. Cleavage of phage DNA by the Streptococcus thermophilus CRISPR3-Cas system. PLoS One 2012; 7:e40913. [PMID: 22911717 PMCID: PMC3401199 DOI: 10.1371/journal.pone.0040913] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2012] [Accepted: 06/15/2012] [Indexed: 12/26/2022] Open
Abstract
Streptococcus thermophilus, similar to other Bacteria and Archaea, has developed defense mechanisms to protect cells against invasion by foreign nucleic acids, such as virus infections and plasmid transformations. One defense system recently described in these organisms is the CRISPR-Cas system (Clustered Regularly Interspaced Short Palindromic Repeats loci coupled to CRISPR-associated genes). Two S. thermophilus CRISPR-Cas systems, CRISPR1-Cas and CRISPR3-Cas, have been shown to actively block phage infection. The CRISPR1-Cas system interferes by cleaving foreign dsDNA entering the cell in a length-specific and orientation-dependant manner. Here, we show that the S. thermophilus CRISPR3-Cas system acts by cleaving phage dsDNA genomes at the same specific position inside the targeted protospacer as observed with the CRISPR1-Cas system. Only one cleavage site was observed in all tested strains. Moreover, we observed that the CRISPR1-Cas and CRISPR3-Cas systems are compatible and, when both systems are present within the same cell, provide increased resistance against phage infection by both cleaving the invading dsDNA. We also determined that overall phage resistance efficiency is correlated to the total number of newly acquired spacers in both CRISPR loci.
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Affiliation(s)
- Alfonso H. Magadán
- Département de Biochimie, de Microbiologie et Bio-Informatiques, Faculté des Sciences et de Génie, Groupe de Recherche en Ecologie Buccale, Université Laval, Québec, Canada
| | - Marie-Ève Dupuis
- Département de Biochimie, de Microbiologie et Bio-Informatiques, Faculté des Sciences et de Génie, Groupe de Recherche en Ecologie Buccale, Université Laval, Québec, Canada
| | - Manuela Villion
- Département de Biochimie, de Microbiologie et Bio-Informatiques, Faculté des Sciences et de Génie, Groupe de Recherche en Ecologie Buccale, Université Laval, Québec, Canada
| | - Sylvain Moineau
- Département de Biochimie, de Microbiologie et Bio-Informatiques, Faculté des Sciences et de Génie, Groupe de Recherche en Ecologie Buccale, Université Laval, Québec, Canada
- Félix d’Hérelle Reference Center for Bacterial Viruses, Université Laval, Québec, Canada
- * E-mail:
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Wang C, Villion M, Semper C, Coros C, Moineau S, Zimmerly S. A reverse transcriptase-related protein mediates phage resistance and polymerizes untemplated DNA in vitro. Nucleic Acids Res 2011; 39:7620-9. [PMID: 21676997 PMCID: PMC3177184 DOI: 10.1093/nar/gkr397] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2011] [Revised: 04/30/2011] [Accepted: 05/03/2011] [Indexed: 01/21/2023] Open
Abstract
Reverse transcriptases (RTs) are RNA-dependent DNA polymerases that usually function in the replication of selfish DNAs such as retrotransposons and retroviruses. Here, we have biochemically characterized a RT-related protein, AbiK, which is required for abortive phage infection in the Gram-positive bacterium Lactococcus lactis. In vitro, AbiK does not exhibit the properties expected for an RT, but polymerizes long DNAs of 'random' sequence, analogous to a terminal transferase. Moreover, the polymerized DNAs appear to be covalently attached to the AbiK protein, presumably because an amino acid serves as a primer. Mutagenesis experiments indicate that the polymerase activity resides in the RT motifs and is essential for phage resistance in vivo. These results establish a novel biochemical property and a non-replicative biological role for a polymerase.
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Affiliation(s)
- Chen Wang
- Department of Biological Sciences, University of Calgary, Calgary, Alberta T2N 1N4, Département de Biochimie, Microbiologie et de Bioinformatique, Faculté des Sciences et de Génie, Université Laval Quebec City, Quebec G1V 0A6 and Groupe de Recherche en Ecologie Buccale (GREB) and Félix d’Hérelle Reference Center for Bacterial Viruses, Faculté de Médecine Dentaire, Université Laval, Quebec City, Quebec G1V 0A6, Canada
| | - Manuela Villion
- Department of Biological Sciences, University of Calgary, Calgary, Alberta T2N 1N4, Département de Biochimie, Microbiologie et de Bioinformatique, Faculté des Sciences et de Génie, Université Laval Quebec City, Quebec G1V 0A6 and Groupe de Recherche en Ecologie Buccale (GREB) and Félix d’Hérelle Reference Center for Bacterial Viruses, Faculté de Médecine Dentaire, Université Laval, Quebec City, Quebec G1V 0A6, Canada
| | - Cameron Semper
- Department of Biological Sciences, University of Calgary, Calgary, Alberta T2N 1N4, Département de Biochimie, Microbiologie et de Bioinformatique, Faculté des Sciences et de Génie, Université Laval Quebec City, Quebec G1V 0A6 and Groupe de Recherche en Ecologie Buccale (GREB) and Félix d’Hérelle Reference Center for Bacterial Viruses, Faculté de Médecine Dentaire, Université Laval, Quebec City, Quebec G1V 0A6, Canada
| | - Colin Coros
- Department of Biological Sciences, University of Calgary, Calgary, Alberta T2N 1N4, Département de Biochimie, Microbiologie et de Bioinformatique, Faculté des Sciences et de Génie, Université Laval Quebec City, Quebec G1V 0A6 and Groupe de Recherche en Ecologie Buccale (GREB) and Félix d’Hérelle Reference Center for Bacterial Viruses, Faculté de Médecine Dentaire, Université Laval, Quebec City, Quebec G1V 0A6, Canada
| | - Sylvain Moineau
- Department of Biological Sciences, University of Calgary, Calgary, Alberta T2N 1N4, Département de Biochimie, Microbiologie et de Bioinformatique, Faculté des Sciences et de Génie, Université Laval Quebec City, Quebec G1V 0A6 and Groupe de Recherche en Ecologie Buccale (GREB) and Félix d’Hérelle Reference Center for Bacterial Viruses, Faculté de Médecine Dentaire, Université Laval, Quebec City, Quebec G1V 0A6, Canada
| | - Steven Zimmerly
- Department of Biological Sciences, University of Calgary, Calgary, Alberta T2N 1N4, Département de Biochimie, Microbiologie et de Bioinformatique, Faculté des Sciences et de Génie, Université Laval Quebec City, Quebec G1V 0A6 and Groupe de Recherche en Ecologie Buccale (GREB) and Félix d’Hérelle Reference Center for Bacterial Viruses, Faculté de Médecine Dentaire, Université Laval, Quebec City, Quebec G1V 0A6, Canada
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Abstract
In this review, we are listing Lactobacillus phages that have been reported in peer-reviewed articles published since 1960. Putative phages that are defective or have not been shown to be infectious, such as phage-like particles, are not discussed. Our literature searches led to the identification of 231 Lactobacillus phages, 186 of which have been observed by electron microscopy, with 109 belonging to the Siphoviridae family, 76 to the Myoviridae family, and 1 to the Podoviridae family. Model phages infecting Lb delbrueckii, casei, rhamnosus, plantarum, and gasseri are highlighted, as well as prophages of Lactobacillus hosts. To date, nine complete Lactobacillus phage genomes are available for comparisons and evolution studies. Features such as phage receptors and endolysins are also reviewed, as well as phage-derived genetic tools. Lactobacillus phage research has progressed significantly over the past decade but a thorough understanding of their biology is still lacking. Because of the risks they represent and the knowledge gaps that need to be filled, the outlook for research on Lactobacillus phages is bright.
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Affiliation(s)
- Manuela Villion
- Departement de biochimie et de microbiologie, Faculte des sciences et de genie, Universite Laval, Quebec City, Quebec, Canada, G1V 0A6
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12
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Abstract
XerC and XerD are two site-specific recombinases, which act on different sites to maintain replicons in a monomeric state. This system, which was first discovered and studied in Escherichia coli, is present in several species including Proteus mirabilis, where the XerD recombinase was previously characterized by our laboratory. In this paper, we report the presence of the xerC gene in P. mirabilis. Using in vitro reactions, we show that the two P. mirabilis recombinases display binding and cleavage activity on the E. coli dif site and the ColE1 cer site, together or in collaboration with E. coli recombinases. In vivo, P. mirabilis XerC and XerD are able to resolve and monomerize a plasmid containing two cer sites, increasing its stability. However, P. mirabilis XerC, in combination with E. coli XerD, is unable to perform these functions.
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Affiliation(s)
- Manuela Villion
- Département de microbiologie et immunologie, Université de Montréal, CP 6128, Succ. Centre-Ville, H3C 3J7, Montreal, QC, Canada
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13
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Abstract
The Xer site-specific recombination system is involved in the stable maintenance of replicons (certain plasmids and chromosomes) in Escherichia coli and other bacteria by converting multimers into monomers. This system requires a cis-acting DNA sequence (the chromosomal dif site or the ColE1 cer site) and two trans-acting factors: the XerC and XerD recombinases, which belong to the lambda integrase family of tyrosine site-specific recombinases. In addition, in order to resolve plasmid multimers into monomers, two additional factors are required: the ArgR and PepA proteins. We have previously shown the presence of xerC and xerD genes (and their function) by Southern hybridisation and by in vivo recombination in a wide variety of Enterobacteriaceac. We have now cloned and sequenced the xerD gene of Proteus mirabilis using degenerate and inverse PCR methods. This gene encodes a tyrosine recombinase which is highly similar to the E. coli XerD recombinase, is capable of complementing an E. coli xerD mutant, and displays sequence-specific DNA binding activity.
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Affiliation(s)
- M Villion
- Dèpartement de Microbiologie et Immunologie, Université de Montréal, Que., Canada
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