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Bioengineering of nisin to enhance functionality against dairy pathogens |
Healy, Brian
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The bacteriocin class of antimicrobial peptides have emerged as a viable alternative to at least partially fill the void created by the end of the golden age of antibiotic discovery. Along with this potential use in a clinical setting, bacteriocins also play an important role as bio-preservatives in the food industry. This thesis focuses on a specific bacteriocin group, the lantibiotics (Lanthionine-containing antibiotics). Their numerous methods of appliance in a food setting and how their gene-encoded nature can be modified to improve on overall bioactivity and functionality are explored here. The use of a lantibiotic (lacticin 3147) producing starter culture to control the Crohn’s disease-linked pathogen Mycobacterium paratuberculosis was assessed in a raw milk cheese. Although lacticin 3147 production did not effectively control the pathogen, the study provided an impetus to employ a variety of PCR-based mutagenesis techniques with a view to the creation of enhanced lantibiotic derivatives. Through the use of these techniques, a number of enhanced derivatives were generated from the ‘hinge’ region of the nisin peptide. Furthermore, a derivative in which the three hinge amino acids were replaced with three alanines represents the first enhanced derivative of nisin to have been designed through a rational process. This derivative also formed the backbone for the creation of an active, trypsin resistant, variant. Through the employment of further mutagenesis methods a derivative was created with potential use as an oral anti-bacterial in the future. Finally a number of lead nisin derivatives were investigated to assess their anti- Streptococcus agalactiae ability, a mastitis associated pathogen. Also a system was developed to facilitate the large scale production of these candidates, or other nisin derivatives, from dairy substrates.
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Keyword(s):
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Nisin; Lacticin 3147; Bacteriocin; Lantibiotic; Mutagenesis; Bioengineering; Streptococcus agalactiae; Mycobacterium avium subspecies paratuberculosis; Lactococcus lactis |
Publication Date:
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2014 |
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Type:
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Doctoral thesis |
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Peer-Reviewed:
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No |
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Language(s):
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English |
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Institution:
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University College Cork |
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Funder(s):
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Teagasc |
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Citation(s):
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Healy, B. C. 2014. Bioengineering of nisin to enhance functionality against dairy pathogens. PhD Thesis, University College Cork. |
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Publisher(s):
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University College Cork |
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File Format(s):
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application/pdf |
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Supervisor(s):
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Hill, Colin
Cotter, Paul D.
Ross, R. Paul |
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First Indexed:
2016-07-13 05:49:35 Last Updated:
2017-09-06 06:30:35 |
