Emily Munson | 2025 I.S. Symposium

Name:Emily Munson
Title: An Investigation of Cross-Resistance and its Genetic Bases in Pseudomonas chlororaphis 14B11 Mutants
Major: Biochemistry and Molecular Biology
Advisor: Stephanie Strand

With antibiotic resistance becoming a more prevalent problem, bacteriophages provide hope as a potential alternative therapeutic. However, bacteria can evolve resistance to phages and even demonstrate cross-resistance to multiple phages. In order for phage therapy to become a more viable treatment option, a greater understanding of phage resistance mechanisms and cross-resistance patterns is necessary. This project aimed to contribute to this area of scientific need by investigating a set of P. chlororaphis 14B11 mutants with evolved resistance to different phage treatments. Profiling of cross-resistance in the mutant strains found that all but PC1M5 were resistant to every bacteriophage tested, including to those which they had not previously been exposed. Whole-genome sequencing identified mutations in two genes involved in the biosynthesis of potential phage receptors – rfbG in PC1M1 and flhA in SM4 – as well as one in a gene encoding a transcriptional regulator – malT in SM4. Whether the identified variations have deleterious effects that interfere with phage infection must be confirmed before conclusions can be drawn regarding the mechanisms of resistance of these mutant strains. Overall, as exposure to both single bacteriophages and cocktails lead to the evolution of cross-resistant mutants, a deeper understanding of phage resistance appears necessary before phage therapy can become a viable alternative to antibiotics.

Posted in Symposium 2025 on May 1, 2025.