Establishing a Combined Phylodynamic and Phylogenomic Comparison of Clostridioides

Undergraduate #126
Discipline: Biological Sciences
Subcategory: Microbiology/Immunology/Virology

Selena Williams - North Carolina Agricultural and Technical State University
Co-Author(s): Scott Harrison, North Carolina Agricultural and Technical State University, Greensboro, NC

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We are investigating differences in 16S gene variation and geographic distribution for the bacterial superstrains Clostridiodes difficile and Staphylococcus aureus. Multiple strains from each of these two types of bacteria were analyzed for diversity within the USA region in comparison to the world. We hypothesize that these two strains will have different phylodynamics due in part to varying geographic and epidemiologic factors. We used Sackin’s Index and Colless’ Imbalance to quantify the topology of the generated phylogenetic trees. Asymmetry of the phylogenetic trees revealed patterns of selection and expansion. Our general finding is that C. difficile expands within the USA more asymmetrically than S. aureus, but less asymmetrically on a global scale. Our overall interpretation is that regional selection appears to be strongest for C. difficile strains as opposed to S. aureus strains. For further verification and inquiry, we have begun investigating the genomic variation that correlates with this observed pattern as well as expanding our scope to other bacterial superstrains.

Not Submitted

Funder Acknowledgement(s): NSF HBCU-UP Data Science & Analytics Advancing STEM Ed

Faculty Advisor: Scott Harrison, scotth@ncat.edu

Role: I was responsible for analyzing the geneomic profile of the bacterial strains and generating phylogenetic trees. In addition, the background information about the bacterial strains, such as their associated diseases and virulence were researched to produce these results. Also, the evolutionary selection of these traits measured through Sackin's index and Colless' imbalance were researched and calculated.