Keira Cozens

2021 PhD Studentship
Bacterial evolution
The fitness effects of loss-of-function mutations in bacterial populations
Milner Centre for Evolution, University of Bath


I became interested in evolution by studying antibiotic resistance in bacteria. Because bacteria reproduce so quickly, we can study evolution in real time and understand some of its immediate consequences, such as spreading illnesses.

The goal of my research is to look at gene loss in bacteria and assess the consequences of this gene loss.

Bacterial evolution matters

Bacteria are small organisms that can live on humans, animals, and in the environment, among many other places. Bacteria can be an important part of the human body, for example in the human gut where they can help break down food. However, bacteria can also cause infections in humans and can spread between humans, animals, and the environment.

Bacteria Staphylococcus aureus from bats grown on agar plates. Photo: Keira Cozens
Constantly evolving

When we think about evolution, we think about the passing on of genes. This is true when studying bacteria. Bacteria may become more dangerous if they gain certain genes. For example, bacteria may become a threat to human health if they gain genes that provide resistance against antibiotics. However, bacteria can also evolve by losing genes, and they may even lose genes faster than they gain them.

The consequences of gene loss in bacteria are not as well-known and some studies show that bacteria can become more dangerous when they lose genes. This is not an intuitive result and it warrants further exploration. Through my research I hope to add to the knowledge that gene loss is a major force for bacterial evolution.

Antibiotic resistance

As part of my research I study the bacterium Klebsiella pneumoniae from multiple geographic locations. This is one of the most common hospital pathogens and it is becoming resistant to antibiotics. I hope that my research will provide answers for how this bacterium can adapt to different hosts, including whether a strain from animals may pass on to humans.

The bacterium Klebsiella pneumoniae growing on CAS agar. Photo: Keira Cozens

After my PhD I would like to continue to research bacterial evolution and its real-world applications. I would also like to continue to engage in science communication projects. I believe the open sharing of genomic datasets and the explaining of leading-edge science to the public helps scientists build on the back of previous work and inspire the next generation of researchers.

The EET scholarship is helping me achieve my ambitions through supporting not only my extensive scientific training, but also my training in outreach.

More about Keira’s research:

Researcher profile