GLORIA

GEOMAR Library Ocean Research Information Access

X

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Online Resource
    Online Resource
    High Prevalence and Genetic Diversity of Large phiCD211 (phiCDIF1296T)-Like Prophages in Clostridioides difficile
    American Society for Microbiology ; 2018
    In:  Applied and Environmental Microbiology Vol. 84, No. 3 ( 2018-02)
    Details
    In: Applied and Environmental Microbiology, American Society for Microbiology, Vol. 84, No. 3 ( 2018-02)
    Abstract: Clostridioides difficile (formerly Clostridium difficile ) is a pathogenic bacterium displaying great genetic diversity. A significant proportion of this diversity is due to the presence of integrated prophages. Here, we provide an in-depth analysis of phiCD211, also known as phiCDIF1296T, the largest phage identified in C. difficile so far, with a genome of 131 kbp. It shares morphological and genomic similarity with other large siphophages, like phage 949, infecting Lactococcus lactis , and phage c-st, infecting Clostridium botulinum . A PhageTerm analysis indicated the presence of 378-bp direct terminal repeats at the phiCD211 genome termini. Among striking features of phiCD211, the presence of several transposase and integrase genes suggests past recombination events with other mobile genetic elements. Several gene products potentially influence the bacterial lifestyle and fitness, including a putative AcrB/AcrD/AcrF multidrug resistance protein, an EzrA septation ring formation regulator, and a spore protease. We also identified a CRISPR locus and a cas3 gene. We screened 2,584 C. difficile genomes available and detected 149 prophages sharing ≥80% nucleotide identity with phiCD211 (5% prevalence). Overall, phiCD211-like phages were detected in C. difficile strains corresponding to 21 different multilocus sequence type groups, showing their high prevalence. Comparative genomic analyses revealed the existence of several clusters of highly similar phiCD211-like phages. Of note, large chromosome inversions were observed in some members, as well as multiple gene insertions and module exchanges. This highlights the great plasticity and gene coding potential of the phiCD211/phiCDIF1296T genome. Our analyses also suggest active evolution involving recombination with other mobile genetic elements. IMPORTANCE Clostridioides difficile is a clinically important pathogen representing a serious threat to human health. Our hypothesis is that genetic differences between strains caused by the presence of integrated prophages could explain the apparent differences observed in the virulence of different C. difficile strains. In this study, we provide a full characterization of phiCD211, also known as phiCDIF1296T, the largest phage known to infect C. difficile so far. Screening 2,584 C. difficile genomes revealed the presence of highly similar phiCD211-like phages in 5% of the strains analyzed, showing their high prevalence. Multiple-genome comparisons suggest that evolution of the phiCD211-like phage community is dynamic, and some members have acquired genes that could influence bacterial biology and fitness. Our study further supports the relevance of studying phages in C. difficile to better understand the epidemiology of this clinically important human pathogen.
    Type of Medium: Online Resource
    ISSN: 0099-2240 , 1098-5336
    URL: Article
    DOI: 10.1128/AEM.02164-17
    RVK:
    WA 15000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2018
    detail.hit.zdb_id: 223011-2
    detail.hit.zdb_id: 1478346-0
    SSG: 12
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 2
    Online Resource
    Online Resource
    The RyfA small RNA regulates oxidative and osmotic stress responses and virulence in uropathogenic Escherichia coli
    Public Library of Science (PLoS) ; 2021
    In:  PLOS Pathogens Vol. 17, No. 5 ( 2021-5-27), p. e1009617-
    Details
    In: PLOS Pathogens, Public Library of Science (PLoS), Vol. 17, No. 5 ( 2021-5-27), p. e1009617-
    Abstract: Urinary tract infections (UTIs) are a common bacterial infectious disease in humans, and strains of uropathogenic Escherichia coli (UPEC) are the most frequent cause of UTIs. During infection, UPEC must cope with a variety of stressful conditions in the urinary tract. Here, we demonstrate that the small RNA (sRNA) RyfA of UPEC strains is required for resistance to oxidative and osmotic stresses. Transcriptomic analysis of the ryfA mutant showed changes in expression of genes associated with general stress responses, metabolism, biofilm formation and genes coding for cell surface proteins. Inactivation of ryfA in UPEC strain CFT073 decreased urinary tract colonization in mice and the ryfA mutant also had reduced production of type 1 and P fimbriae (pili), adhesins which are known to be important for UTI. Furthermore, loss of ryfA also reduced UPEC survival in human macrophages. Thus, ryfA plays a key regulatory role in UPEC adaptation to stress, which contributes to UTI and survival in macrophages.
    Type of Medium: Online Resource
    ISSN: 1553-7374
    URL: Article
    URL: Article
    URL: Article
    URL: Article
    URL: Article
    URL: Article
    URL: Article
    URL: Article
    URL: Article
    URL: Article
    URL: Article
    URL: Article
    URL: Article
    URL: Article
    URL: Article
    URL: Article
    URL: Article
    URL: Article
    URL: Article
    URL: Article
    URL: Article
    DOI: 10.1371/journal.ppat.1009617
    DOI: 10.1371/journal.ppat.1009617.g001
    DOI: 10.1371/journal.ppat.1009617.g002
    DOI: 10.1371/journal.ppat.1009617.g003
    DOI: 10.1371/journal.ppat.1009617.g004
    DOI: 10.1371/journal.ppat.1009617.g005
    DOI: 10.1371/journal.ppat.1009617.g006
    DOI: 10.1371/journal.ppat.1009617.g007
    DOI: 10.1371/journal.ppat.1009617.s001
    DOI: 10.1371/journal.ppat.1009617.s002
    DOI: 10.1371/journal.ppat.1009617.s003
    DOI: 10.1371/journal.ppat.1009617.s004
    DOI: 10.1371/journal.ppat.1009617.s005
    DOI: 10.1371/journal.ppat.1009617.s006
    DOI: 10.1371/journal.ppat.1009617.s007
    DOI: 10.1371/journal.ppat.1009617.s008
    DOI: 10.1371/journal.ppat.1009617.s009
    DOI: 10.1371/journal.ppat.1009617.s010
    DOI: 10.1371/journal.ppat.1009617.s011
    DOI: 10.1371/journal.ppat.1009617.s012
    DOI: 10.1371/journal.ppat.1009617.s013
    Language: English
    Publisher: Public Library of Science (PLoS)
    Publication Date: 2021
    detail.hit.zdb_id: 2205412-1
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 3
    Online Resource
    Online Resource
    Ehrlichia Isolate from a Minnesota Tick: Characterization and Genetic Transformation
    American Society for Microbiology ; 2019
    In:  Applied and Environmental Microbiology Vol. 85, No. 14 ( 2019-07-15)
    Details
    In: Applied and Environmental Microbiology, American Society for Microbiology, Vol. 85, No. 14 ( 2019-07-15)
    Abstract: Ehrlichia muris subsp. eauclairensis is recognized as the etiological agent of human ehrlichiosis in Minnesota and Wisconsin. We describe the culture isolation of this organism from a field-collected tick and detail its relationship to other species of Ehrlichia . The isolate could be grown in a variety of cultured cell lines and was effectively transmitted between Ixodes scapularis ticks and rodents, with PCR and microscopy demonstrating a broad pattern of dissemination in arthropod and mammalian tissues. Conversely, Amblyomma americanum ticks were not susceptible to infection by the Ehrlichia . Histologic sections further revealed that the wild-type isolate was highly virulent for mice and hamsters, causing severe systemic disease that was frequently lethal. A Himar1 transposase system was used to create mCherry- and mKate-expressing EmCRT mutants, which retained the ability to infect rodents and ticks. IMPORTANCE Ehrlichioses are zoonotic diseases caused by intracellular bacteria that are transmitted by ixodid ticks. Here we report the culture isolation of bacteria which are closely related to, or the same as the Ehrlichia muris subsp. eauclairensis , a recently recognized human pathogen. EmCRT, obtained from a tick removed from deer at Camp Ripley, MN, is the second isolate of this subspecies described and is distinctive in that it was cultured directly from a field-collected tick. The isolate’s cellular tropism, pathogenic changes caused in rodent tissues, and tick transmission to and from rodents are detailed in this study. We also describe the genetic mutants created from the EmCRT isolate, which are valuable tools for the further study of this intracellular pathogen.
    Type of Medium: Online Resource
    ISSN: 0099-2240 , 1098-5336
    URL: Article
    DOI: 10.1128/AEM.00866-19
    RVK:
    WA 15000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2019
    detail.hit.zdb_id: 223011-2
    detail.hit.zdb_id: 1478346-0
    SSG: 12
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 4
    Online Resource
    Online Resource
    Strain-Specific Metabolic Requirements Revealed by a Defined Minimal Medium for Systems Analyses of Staphylococcus aureus
    American Society for Microbiology ; 2019
    In:  Applied and Environmental Microbiology Vol. 85, No. 21 ( 2019-11)
    Details
    In: Applied and Environmental Microbiology, American Society for Microbiology, Vol. 85, No. 21 ( 2019-11)
    Abstract: Staphylococcus aureus is a Gram-positive pathogenic bacterium that colonizes an estimated one-third of the human population and can cause a wide spectrum of disease, ranging from superficial skin infections to life-threatening sepsis. The adaptive mechanisms that contribute to the success of this pathogen remain obscure partially due to a lack of knowledge of its metabolic requirements. Systems biology approaches can be extremely useful in predicting and interpreting metabolic phenotypes; however, such approaches rely on a chemically defined minimal medium as a basis to investigate the requirements of the cell. In this study, a chemically defined minimal medium formulation, termed synthetic minimal medium (SMM), was investigated and validated to support growth of three S. aureus strains: LAC and TCH1516 (USA300 lineage), as well as D592 (USA100 lineage). The formulated SMM was used in an adaptive laboratory evolution experiment to probe the various mutational trajectories of all three strains leading to optimized growth capabilities. The evolved strains were phenotypically characterized for their growth rate and antimicrobial susceptibility. Strains were also resequenced to examine the genetic basis for observed changes in phenotype and to design follow-up metabolite supplementation assays. Our results reveal evolutionary trajectories that arose from strain-specific metabolic requirements. SMM and the evolved strains can also serve as important tools to study antibiotic resistance phenotypes of S. aureus . IMPORTANCE As researchers try to understand and combat the development of antibiotic resistance in pathogens, there is a growing need to thoroughly understand the physiology and metabolism of the microbes. Staphylococcus aureus is a threatening pathogen with increased antibiotic resistance and well-studied virulence mechanisms. However, the adaptive mechanisms used by this pathogen to survive environmental stresses remain unclear, mostly due to the lack of information about its metabolic requirements. Defining the minimal metabolic requirements for S. aureus growth is a first step toward unraveling the mechanisms by which it adapts to metabolic stresses. Here, we present the development of a chemically defined minimal medium supporting growth of three S. aureus strains, and we reveal key genetic mutations contributing to improved growth in minimal medium.
    Type of Medium: Online Resource
    ISSN: 0099-2240 , 1098-5336
    URL: Article
    DOI: 10.1128/AEM.01773-19
    RVK:
    WA 15000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2019
    detail.hit.zdb_id: 223011-2
    detail.hit.zdb_id: 1478346-0
    SSG: 12
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 5
    Online Resource
    Online Resource
    Parallel Sequencing Reveals Campylobacter spp. in Commercial Meat Chickens Less than 8 Days Old
    American Society for Microbiology ; 2021
    In:  Applied and Environmental Microbiology Vol. 87, No. 23 ( 2021-11-10)
    Details
    In: Applied and Environmental Microbiology, American Society for Microbiology, Vol. 87, No. 23 ( 2021-11-10)
    Abstract: Campylobacter from contaminated poultry meat is a major source of human gastroenteritis worldwide. To date, attempts to control this zoonotic infection with on-farm biosecurity measures have been inconsistent in outcome. A cornerstone of these efforts has been the detection of chicken infection with microbiological culture, where Campylobacter is generally not detectable until birds are at least 21 days old. Using parallel sequence-based bacterial 16S profiling analysis and targeted sequencing of the porA gene, Campylobacter was identified at very low levels in all commercial flocks at less than 8 days old that were tested from the United Kingdom, Switzerland, and France. These young chicks exhibited a much greater diversity of porA types than older birds testing positive for Campylobacter by culture or quantitative PCR (qPCR). This suggests that as the bacteria multiply sufficiently to be detected by culture methods, one or two variants, as indicated by porA type, dominate the infection. The findings that (i) most young chicks carry some Campylobacter and (ii) not all flocks become Campylobacter positive by culture suggest that efforts to control infection, and therefore avoid contamination of poultry meat, should concentrate on how to limit Campylobacter to low levels by the prevention of the overgrowth of single strains. IMPORTANCE Our results demonstrate the presence of Campylobacter DNA among fecal samples from a range of commercially reared meat chicks that are less than 8 days of age, consistent across 3 European countries. The recently developed, sensitive detection method indicates that infection occurs on commercial farms much earlier and more widely than previously thought, which opens up new opportunities to control Campylobacter contamination at the start of the food chain and reduce the unacceptably high levels of human disease.
    Type of Medium: Online Resource
    ISSN: 0099-2240 , 1098-5336
    URL: Article
    DOI: 10.1128/AEM.01060-21
    RVK:
    WA 15000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2021
    detail.hit.zdb_id: 223011-2
    detail.hit.zdb_id: 1478346-0
    SSG: 12
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 6
    Online Resource
    Online Resource
    Salmonella Genomics and Population Analyses Reveal High Inter- and Intraserovar Diversity in Freshwater
    American Society for Microbiology ; 2021
    In:  Applied and Environmental Microbiology Vol. 87, No. 6 ( 2021-02-26)
    Details
    In: Applied and Environmental Microbiology, American Society for Microbiology, Vol. 87, No. 6 ( 2021-02-26)
    Abstract: Freshwater can support the survival of the enteric pathogen Salmonella , though temporal Salmonella diversity in a large watershed has not been assessed. At 28 locations within the Susquehanna River basin, 10-liter samples were assessed in spring and summer over 2 years. Salmonella prevalence was 49%, and increased river discharge was the main driver of Salmonella presence. The amplicon-based sequencing tool, CRISPR-SeroSeq, was used to determine serovar population diversity and detected 25 different Salmonella serovars, including up to 10 serovars from a single water sample. On average, there were three serovars per sample, and 80% of Salmonella -positive samples contained more than one serovar. Serovars Give, Typhimurium, Thompson, and Infantis were identified throughout the watershed and over multiple collections. Seasonal differences were evident: serovar Give was abundant in the spring, whereas serovar Infantis was more frequently identified in the summer. Eight of the ten serovars most commonly associated with human illness were detected in this study. Crucially, six of these serovars often existed in the background, where they were masked by a more abundant serovar(s) in a sample. Serovars Enteritidis and Typhimurium, especially, were masked in 71 and 78% of samples where they were detected, respectively. Whole-genome sequencing-based phylogeny demonstrated that strains within the same serovar collected throughout the watershed were also very diverse. The Susquehanna River basin is the largest system where Salmonella prevalence and serovar diversity have been temporally and spatially investigated, and this study reveals an extraordinary level of inter- and intraserovar diversity. IMPORTANCE Salmonella is a leading cause of bacterial foodborne illness in the United States, and outbreaks linked to fresh produce are increasing. Understanding Salmonella ecology in freshwater is of importance, especially where irrigation practices or recreational use occur. As the third largest river in the United States east of the Mississippi, the Susquehanna River is the largest freshwater contributor to the Chesapeake Bay, and it is the largest river system where Salmonella diversity has been studied. Rainfall and subsequent high river discharge rates were the greatest indicators of Salmonella presence in the Susquehanna and its tributaries. Several Salmonella serovars were identified, including eight commonly associated with foodborne illness. Many clinically important serovars were present at a low frequency within individual samples and so could not be detected by conventional culture methods. The technologies employed here reveal an average of three serovars in a 10-liter sample of water and up to 10 serovars in a single sample.
    Type of Medium: Online Resource
    ISSN: 0099-2240 , 1098-5336
    URL: Article
    DOI: 10.1128/AEM.02594-20
    RVK:
    WA 15000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2021
    detail.hit.zdb_id: 223011-2
    detail.hit.zdb_id: 1478346-0
    SSG: 12
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 7
    Online Resource
    Online Resource
    Multidrug and Mupirocin Resistance in Environmental Methicillin-Resistant Staphylococcus aureus (MRSA) Isolates from Homes of People Diagnosed with Community-Onset MRSA Infection
    American Society for Microbiology ; 2017
    In:  Applied and Environmental Microbiology Vol. 83, No. 22 ( 2017-11-15)
    Details
    In: Applied and Environmental Microbiology, American Society for Microbiology, Vol. 83, No. 22 ( 2017-11-15)
    Abstract: Patients with community-onset (CO) methicillin-resistant Staphylococcus aureus (MRSA) infections contribute to MRSA contamination of the home environment and may be reexposed to MRSA strains from this reservoir. This study evaluates One Health risk factors, which focus on the relationship between humans, animals, and the environment, for the increased prevalence of multiple antimicrobial-resistant MRSA isolates in the home environment. During a trial of patients with CO-MRSA infection, MRSA was isolated from the household environment at the baseline and 3 months later, following randomization of patients and household members to mupirocin-based decolonization therapy or an education control group. Up to two environmental MRSA isolates collected at each visit were tested. MRSA isolates were identified in 68% (65/95) of homes at the baseline ( n = 104 isolates) and 51% (33/65) of homes 3 months later ( n = 56 isolates). The rates of multidrug resistance (MDR) were 61% among isolates collected at the baseline and 55% among isolates collected at the visit 3 months later. At the baseline, 100% (14/14) of MRSA isolates from rural homes were MDR. While antimicrobial use by humans or pets was associated with an increased risk for the isolation of MDR MRSA from the environment, clindamycin use was not associated with an increased risk for the isolation of MDR MRSA. Incident low-level mupirocin-resistant MRSA strains were isolated at 3 months from 2 (5%) of 39 homes that were randomized to mupirocin treatment but none of the control homes. Among patients recently treated for a CO-MRSA infection, MRSA and MDR MRSA were common contaminants in the home environment. This study contributes to evidence that occupant use of antimicrobial drugs, except for clindamycin, is associated with MDR MRSA in the home environmental reservoir. (This study has been registered at ClinicalTrials.gov under registration no. NCT00966446.) IMPORTANCE MRSA is a common bacterial agent implicated in skin and soft tissue infections (SSTIs) in both community and health care settings. Patients with CO-MRSA infections contribute to environmental MRSA contamination in these settings and may be reexposed to MRSA strains from these reservoirs. People interact with natural and built environments; therefore, understanding the relationships between humans and animals as well as the characteristics of environmental reservoirs is important to advance strategies to combat antimicrobial resistance. Household interactions may influence the frequency and duration of exposure, which in turn may impact the duration of MRSA colonization or the probability for recurrent colonization and infection. Therefore, MRSA contamination of the home environment may contribute to human and animal recolonization and decolonization treatment failure. The aim of this study was to evaluate One Health risk factors that may be amenable to intervention and may influence the recovery of MDR and mupirocin resistance in CO-MRSA isolates.
    Type of Medium: Online Resource
    ISSN: 0099-2240 , 1098-5336
    URL: Article
    DOI: 10.1128/AEM.01369-17
    RVK:
    WA 15000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2017
    detail.hit.zdb_id: 223011-2
    detail.hit.zdb_id: 1478346-0
    SSG: 12
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 8
    Online Resource
    Online Resource
    Reduced Antibacterial Drug Resistance and bla CTX-M β-Lactamase Gene Carriage in Cattle-Associated Escherichia coli at Low Temperatures, at Sites Dominated by Older Animals, and on Pastureland: Implications for Surveillance
    American Society for Microbiology ; 2021
    In:  Applied and Environmental Microbiology Vol. 87, No. 6 ( 2021-02-26)
    Details
    In: Applied and Environmental Microbiology, American Society for Microbiology, Vol. 87, No. 6 ( 2021-02-26)
    Abstract: Little is known about the drivers of critically important antibacterial resistance in species with zoonotic potential present on farms (e.g., CTX-M β-lactamase-positive Escherichia coli ). We collected samples monthly between January 2017 and December 2018 on 53 dairy farms in South West England, along with data for 610 variables concerning antibacterial usage, management practices, and meteorological factors. We detected E. coli resistant to amoxicillin, ciprofloxacin, streptomycin, and tetracycline in 2,754/4,145 (66%), 263/4,145 (6%), 1,475/4,145 (36%), and 2,874/4,145 (69%), respectively, of samples from fecally contaminated on-farm and near-farm sites. E. coli positive for bla CTX-M were detected in 224/4,145 (5.4%) of samples. Multilevel, multivariable logistic regression showed antibacterial dry cow therapeutic choice (including use of cefquinome or framycetin) to be associated with higher odds of bla CTX-M positivity. Low average monthly ambient temperature was associated with lower odds of bla CTX-M E. coli positivity in samples and with lower odds of finding E. coli resistant to each of the four test antibacterials. This was in addition to the effect of temperature on total E. coli density. Furthermore, samples collected close to calves had higher odds of having E. coli resistant to each antibacterial, as well as E. coli positive for bla CTX-M . Samples collected on pastureland had lower odds of having E. coli resistant to amoxicillin or tetracycline, as well as lower odds of being positive for bla CTX-M . IMPORTANCE Antibacterial resistance poses a significant threat to human and animal health and global food security. Surveillance for resistance on farms is important for many reasons, including tracking impacts of interventions aimed at reducing the prevalence of resistance. In this longitudinal survey of dairy farm antibacterial resistance, we showed that local temperature—as it changes over the course of a year—was associated with the prevalence of antibacterial-resistant E. coli . We also showed that prevalence of resistant E. coli was lower on pastureland and higher in environments inhabited by young animals. These findings have profound implications for routine surveillance and for surveys carried out for research. They provide important evidence that sampling at a single time point and/or single location on a farm is unlikely to be adequate to accurately determine the status of the farm regarding the presence of samples containing resistant E. coli .
    Type of Medium: Online Resource
    ISSN: 0099-2240 , 1098-5336
    URL: Article
    DOI: 10.1128/AEM.01468-20
    RVK:
    WA 15000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2021
    detail.hit.zdb_id: 223011-2
    detail.hit.zdb_id: 1478346-0
    SSG: 12
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 9
    Online Resource
    Online Resource
    Locus of Heat Resistance (LHR) in Meat-Borne Escherichia coli: Screening and Genetic Characterization
    American Society for Microbiology ; 2021
    In:  Applied and Environmental Microbiology Vol. 87, No. 7 ( 2021-03-11)
    Details
    In: Applied and Environmental Microbiology, American Society for Microbiology, Vol. 87, No. 7 ( 2021-03-11)
    Abstract: Microbial resistance to processing treatments poses a food safety concern, as treatment tolerant pathogens can emerge. Occasional foodborne outbreaks caused by pathogenic Escherichia coli have led to human and economic losses. Therefore, this study screened for the extreme heat resistance (XHR) phenotype as well as one known genetic marker, the locus of heat resistance (LHR), in 4,123 E. coli isolates from diverse meat animals at different processing stages. The prevalences of XHR and LHR among the meat-borne E. coli were found to be 10.3% and 11.4%, respectively, with 19% agreement between the two. Finished meat products showed the highest LHR prevalence (24.3%) compared to other processing stages (0 to 0.6%). None of the LHR + E. coli in this study would be considered pathogens based on screening for virulence genes. Four high-quality genomes were generated by whole-genome sequencing of representative LHR + isolates. Nine horizontally acquired LHRs were identified and characterized, four plasmid-borne and five chromosomal. Nine newly identified LHRs belong to ClpK1 LHR or ClpK2 LHR variants sharing 61 to 68% nucleotide sequence identity, while one LHR appears to be a hybrid. Our observations suggest positive correlation between the number of LHR regions present in isolates and the extent of heat resistance. The isolate exhibiting the highest degree of heat resistance possessed four LHRs belonging to three different variant groups. Maintenance of as many as four LHRs in a single genome emphasizes the benefits of the LHR in bacterial physiology and stress response. IMPORTANCE Currently, a “multiple-hurdle” approach based on a combination of different antimicrobial interventions, including heat, is being utilized during meat processing to control the burden of spoilage and pathogenic bacteria. Our recent study (M. Guragain, G. E. Smith, D. A. King, and J. M. Bosilevac, J Food Prot 83:1438–1443, 2020, https://doi.org/10.4315/JFP-20-103 ) suggests that U.S. beef cattle harbor Escherichia coli that possess the locus of heat resistance (LHR). LHR seemingly contributes to the global stress tolerance in bacteria and hence poses a food safety concern. Therefore, it is important to understand the distribution of the LHRs among meat-borne bacteria identified at different stages of different meat processing systems. Complete genome sequencing and comparative analysis of selected heat-resistant bacteria provide a clearer understanding of stress and heat resistance mechanisms. Further, sequencing data may offer a platform to gain further insights into the genetic background that provides optimal bacterial tolerance against heat and other processing treatments.
    Type of Medium: Online Resource
    ISSN: 0099-2240 , 1098-5336
    URL: Article
    DOI: 10.1128/AEM.02343-20
    RVK:
    WA 15000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2021
    detail.hit.zdb_id: 223011-2
    detail.hit.zdb_id: 1478346-0
    SSG: 12
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 10
    Online Resource
    Online Resource
    Longitudinal Study of Lactococcus Phages in a Canadian Cheese Factory
    American Society for Microbiology ; 2023
    In:  Applied and Environmental Microbiology Vol. 89, No. 5 ( 2023-05-31)
    Details
    In: Applied and Environmental Microbiology, American Society for Microbiology, Vol. 89, No. 5 ( 2023-05-31)
    Abstract: The presence of virulent phages is closely monitored during cheese manufacturing, as these bacterial viruses can significantly slow down the milk fermentation process and lead to low-quality cheeses. From 2001 to 2020, whey samples from cheddar cheese production in a Canadian factory were monitored for the presence of virulent phages capable of infecting proprietary strains of Lactococcus cremoris and Lactococcus lactis used in starter cultures. Phages were successfully isolated from 932 whey samples using standard plaque assays and several industrial Lactococcus strains as hosts. A multiplex PCR assay assigned 97% of these phage isolates to the Skunavirus genus, 2% to the P335 group, and 1% to the Ceduovirus genus. DNA restriction profiles and a multilocus sequence typing (MLST) scheme distinguished at least 241 unique lactococcal phages from these isolates. While most phages were isolated only once, 93 of them (out of 241, 39%) were isolated multiple times. Phage GL7 was isolated 132 times from 2006 to 2020, demonstrating that phages can persist in a cheese factory for long periods of time. Phylogenetic analysis of MLST sequences showed that phages could be clustered based on their bacterial hosts rather than their year of isolation. Host range analysis showed that Skunavirus phages exhibited a very narrow host range, whereas some Ceduovirus and P335 phages had a broader host range. Overall, the host range information was useful in improving the starter culture rotation by identifying phage-unrelated strains and helped mitigating the risk of fermentation failure due to virulent phages. IMPORTANCE Although lactococcal phages have been observed in cheese production settings for almost a century, few longitudinal studies have been performed. This 20-year study describes the close monitoring of dairy lactococcal phages in a cheddar cheese factory. Routine monitoring was conducted by factory staff, and when whey samples were found to inhibit industrial starter cultures under laboratory conditions, they were sent to an academic research laboratory for phage isolation and characterization. This led to a collection of at least 241 unique lactococcal phages, which were characterized through PCR typing and MLST profiling. Phages of the Skunavirus genus were by far the most dominant. Most phages lysed a small subset of the Lactococcus strains. These findings guided the industrial partner in adapting the starter culture schedule by using phage-unrelated strains in starter cultures and removing some strains from the starter rotation. This phage control strategy could be adapted for other large-scale bacterial fermentation processes.
    Type of Medium: Online Resource
    ISSN: 0099-2240 , 1098-5336
    URL: Article
    DOI: 10.1128/aem.00421-23
    RVK:
    WA 15000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2023
    detail.hit.zdb_id: 223011-2
    detail.hit.zdb_id: 1478346-0
    SSG: 12
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...