Defense Date


Document Type


Degree Name

Master of Science



First Advisor

Dr. Jennifer M. Fettweis

Second Advisor

Dr. Gregory A. Buck

Third Advisor

Dr. Brian C. Verrelli


Two vaginal phylotypes of the genus Megasphaera (phylotype 1 and phylotype 2) were recently associated with bacterial vaginosis (BV), an infection characterized by vaginal dysbiosis. Through an analysis of 16S rRNA profiles of 3,986 women enrolled in the Vaginal Human Microbiome Project, we confirmed that while both phylotypes were associated with BV, Megaspheara phylotype 1 had higher specificity for the condition. Megasphaera phylotype 2 was strongly associated with trichomoniasis. Previous studies have reported that BV-associated organisms are excluded in pregnancy. We observed that Megasphaera phylotype 1, which has been associated with adverse pregnancy outcomes, exhibited a trend of increased prevalence in the pregnant cohort. We sequenced the genomes of isolates of the two phylotypes and performed comparative analyses. We demonstrate that these two phylotypes have distinct genomic features and unique potential for metabolic processes that reveal niche specialization. These findings may provide insight into their differential associations with vaginal infections.


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Available for download on Wednesday, December 09, 2020