Bioengineering of nisin to enhance functionality against dairy pathogens

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.

Grantor dc:publisher

University College Cork

Year dc:date.issued

2014

Author dc:creator

• Healy, Brian

Advisors dc:contributor.advisor

• Hill, Colin
• Cotter, Paul D.
• Ross, R. Paul

• Nisin
• Lacticin 3147
• Bacteriocin
• Lantibiotic
• Mutagenesis
• Bioengineering
• Streptococcus agalactiae
• Mycobacterium avium subspecies paratuberculosis
• Lactococcus lactis

Statement dc:rights

• © 2014, Brian C. Healy

Licence dc:rights.uri

• http://creativecommons.org/licenses/by-nc-nd/3.0/

Language dc:language.iso

en

Handle dc:identifier.uri

https://hdl.handle.net/10468/2696

OAI identifier oai:identifier

oai:cora.ucc.ie:10468/2696