Matthew Craske

Uncovering the evolutionary impact of Gene Transfer Agents (GTAs) on Rhodobacter capsulatus

About me


Growing up I always had a particular interest in evolution. With a ‘tree of life’ poster on my wall, I wondered how each organism was related and how microorganisms are at the root of it all. During my studies, my interests became focused on antibiotic resistance and the evolutionary arms race between bacteria and phages. I graduated with a First-class degree in Cellular and Molecular Biology at Newcastle University (2019), as well as a Distinction in the MRes Biotechnology and Biodesign, also at Newcastle University (2020). Following this, I worked as a Research Technician at the Liverpool School of Tropical Medicine providing support in molecular biology and insect rearing to research projects performing functional genetics in mosquitoes. During my PhD, I am excited to see the evolutionary impact GTAs have as a mechanism of horizontal gene transfer and how this facilitates adaptations to stressful conditions.


My project


Gene transfer agents (GTAs) are phage-like entities which can transfer genes to surrounding cells via horizontal gene transfer (HGT). Their ability to transfer genes to neighbouring cells through a transduction-like mechanism, as utilised by bacteriophages, has prompted further questions on the influence GTAs have on bacterial evolution. The highly competitive nature of bacterial ecosystems means bacterial genomes are under constant selection. Genes which do not provide a selective advantage are often lost from the population. As GTA production results in cell lysis, the evolutionary benefit responsible for outweighing this cost remains unknown. My project will use experimental evolution, microbiology and genomics to compare wild-type and GTA mutant phenotypes of R. capsulatus under environmentally realistic conditions. Here, we will examine the fitness benefits or costs of various GTA mutants over time. Further understanding of the influence GTAs have on a population under stressful conditions may shed light on their evolutionary function.