The biodiversity, control and genetic characterisation of the lactococcal 936 group phages

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dc.contributor.advisor van Sinderen, Douwe en Murphy, James 2015-11-04T13:37:02Z 2014 2014
dc.identifier.citation Murphy, J. 2014. The biodiversity, control and genetic characterisation of the lactococcal 936 group phages. PhD Thesis, University College Cork. en
dc.description.abstract Phages belonging to the 936 group represent one of the most prevalent and frequently isolated phages in dairy fermentation processes using Lactococcus lactis as the primary starter culture. In recent years extensive research has been carried out to characterise this phage group at a genomic level in an effort to understand how the 936 group phages dominate this particular niche and cause regular problems during large scale milk fermentations. This thesis describes a large scale screening of industrial whey samples, leading to the isolation of forty three genetically different lactococcal phages. Using multiplex PCR, all phages were identified as members of the 936 group. The complete genome of thirty eight of these phages was determined using next generation sequencing technologies which identified several regions of divergence. These included the structural region surrounding the major tail protein, the replication region as well as the genes involved in phage DNA packing. For a number of phages the latter genomic region was found to harbour genes encoding putative orphan methyltransferases. Using small molecule real time (SMRT) sequencing and heterologous gene expression, the target motifs for several of these MTases were determined and subsequently shown to actively protect phage DNA from restriction endonuclease activity. Comparative analysis of the thirty eight phages with fifty two previously sequenced members of this group showed that the core genome consists of 28 genes, while the non-core genome was found to fluctuate irrespective of geographical location or time of isolation. This study highlights the continued need to perform large scale characterisation of the bacteriophage populations infecting industrial fermentation facilities in effort to further our understanding dairy phages and ways to control their proliferation. en
dc.description.sponsorship Irish Research Council (Enterprise Partnership Scheme) en
dc.format.mimetype application/pdf en
dc.language.iso en en
dc.publisher University College Cork en
dc.rights © 2014, James Murphy. en
dc.rights.uri en
dc.subject Phage en
dc.subject Dairy en
dc.subject Lactococcus lactis en
dc.title The biodiversity, control and genetic characterisation of the lactococcal 936 group phages en
dc.type Doctoral thesis en
dc.type.qualificationlevel Doctoral Degree (Structured) en
dc.type.qualificationname PhD (Science) en
dc.internal.availability Full text not available en Indefinite en 10000-01-01
dc.description.version Accepted Version
dc.contributor.funder Irish Research Council en
dc.description.status Not peer reviewed en Microbiology en
dc.check.reason Releasing this thesis would cause substantial prejudice to the commercial interests of the sponsor of the postgraduate research en
dc.check.opt-out Yes en
dc.thesis.opt-out true
dc.check.entireThesis Entire Thesis Restricted
dc.check.embargoformat E-thesis on CORA only en
dc.internal.conferring Spring Conferring 2015

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© 2014, James Murphy. Except where otherwise noted, this item's license is described as © 2014, James Murphy.
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