Integrative conjugative elements of the lactococcal variety;A study in form and function

Summary

Integrative conjugative elements (ICEs) are DNA ‘organisms’ that can travel between bacterial cells. This form of horizontal gene transfer is a main driver of bacterial evolution and adaptation to environments. ICEs might be able to play a role in strain enhancement of lactic acid bacteria (LAB), which are typically used in dairy fermentation. In this work we investigated both their potential for application and their fundamental biology: their taxonomy and lifecycle. This PhD research was a dive into the lactococcal ICE populations, discovering how many there are, what their composition is like, how they are related and how they can be transferred between lactococcal cells. We developed some biotechnological tools to study these elements with such as CRISPR-Cas9 curing and silencing as well as single molecule microscopy setups, the results of which are published in this thesis.