Dataset Information

Comparative genomic and morphological analyses of Listeria phages isolated from farm environments.

ABSTRACT: The genus Listeria is ubiquitous in the environment and includes the globally important food-borne pathogen Listeria monocytogenes. While the genomic diversity of Listeria has been well studied, considerably less is known about the genomic and morphological diversity of Listeria bacteriophages. In this study, we sequenced and analyzed the genomes of 14 Listeria phages isolated mostly from New York dairy farm environments as well as one related Enterococcus faecalis phage to obtain information on genome characteristics and diversity. We also examined 12 of the phages by electron microscopy to characterize their morphology. These Listeria phages, based on gene orthology and morphology, together with previously sequenced Listeria phages could be classified into five orthoclusters, including one novel orthocluster. One orthocluster (orthocluster I) consists of large genome (~135-kb) myoviruses belonging to the genus “Twort-like viruses,” three orthoclusters (orthoclusters II to IV) contain small-genome (36- to 43-kb) siphoviruses with icosahedral heads, and the novel orthocluster V contains medium-sized-genome (~66-kb) siphoviruses with elongated heads. A novel orthocluster (orthocluster VI) of E. faecalis phages, with medium-sized genomes (~56 kb), was identified, which grouped together and shares morphological features with the novel Listeria phage orthocluster V. This new group of phages (i.e., orthoclusters V and VI) is composed of putative lytic phages that may prove to be useful in phage-based applications for biocontrol, detection, and therapeutic purposes.

SUBMITTER: Denes T

PROVIDER: S-EPMC4148797 | biostudies-literature | 2014 Aug

REPOSITORIES: biostudies-literature

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Comparative genomic and morphological analyses of Listeria phages isolated from farm environments.

Denes Thomas T Vongkamjan Kitiya K Ackermann Hans-Wolfgang HW Moreno Switt Andrea I AI Wiedmann Martin M den Bakker Henk C HC

Applied and environmental microbiology 20140801 15

The genus Listeria is ubiquitous in the environment and includes the globally important food-borne pathogen Listeria monocytogenes. While the genomic diversity of Listeria has been well studied, considerably less is known about the genomic and morphological diversity of Listeria bacteriophages. In this study, we sequenced and analyzed the genomes of 14 Listeria phages isolated mostly from New York dairy farm environments as well as one related Enterococcus faecalis phage to obtain information on ...[more]

PMID: 24837381

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Project description:AbstractA comprehensive understanding of foodborne pathogen diversity in preharvest environments is necessary to effectively track pathogens on farms and identify sources of produce contamination. As such, this study aimed to characterize Listeria diversity in wildlife feces and agricultural water collected from a New York state produce farm over a growing season. Water samples were collected from a pond (n = 80) and a stream (n = 52). Fecal samples (n = 77) were opportunistically collected from areas <5 m from the water sources; all samples were collected from a <0.5-km2 area. Overall, 86 (41%) and 50 (24%) of 209 samples were positive for Listeria monocytogenes and Listeria spp. (excluding L. monocytogenes), respectively. For each positive sample, one L. monocytogenes or Listeria spp. isolate was speciated by sequencing the sigB gene, thereby allowing for additional characterization based on the sigB allelic type. The 86 L. monocytogenes and 50 Listeria spp. isolates represented 8 and 23 different allelic types, respectively. A subset of L. monocytogenes isolates (n = 44) from pond water and pond-adjacent feces (representing an ∼5,000-m2 area) were further characterized by pulsed-field gel electrophoresis (PFGE); these 44 isolates represented 22 PFGE types, which is indicative of considerable diversity at a small spatial scale. Ten PFGE types were isolated more than once, suggesting persistence or reintroduction of PFGE types in this area. Given the small spatial scale, the prevalence of L. monocytogenes and Listeria spp., as well as the considerable diversity among isolates, suggests traceback investigations may be challenging. For example, traceback of finished product or processing facility contamination with specific subtypes to preharvest sources may require collection of large sample sets and characterization of a considerable number of isolates. Our data also support the adage "absence of evidence does not equal evidence of absence" as applies to L. monocytogenes traceback efforts at the preharvest level.Highlights

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Dataset Information

Comparative genomic and morphological analyses of Listeria phages isolated from farm environments.

Publications

Comparative genomic and morphological analyses of Listeria phages isolated from farm environments.

Similar Datasets

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