Engineering a Local Acidification Probiotic and Defined Culture Platform for Bacterial Vaginosis Microbiome Remediation

• Iris Zhang, Chemical Engineering, University of Delaware

• Aditya Kunjapur, Chemical & Biomolecular Engineering, University of Delaware

Global healthcare expenditure attributed to bacterial vaginosis (BV), a polymicrobial vaginal disorder characterized by loss of Lactobacillus dominance and elevated pH, is estimated at $4.8 billion (USD) annually for women of reproductive age. This burden persists despite widespread use of antibiotics such as metronidazole and clindamycin, as BV recurs in up to 70% of affected women. Current alternative treatments that reacidify the cervicovaginal environment have also fallen short, providing only temporary symptomatic relief and resulting in similarly high relapse rates. To ensure sustained acidification to suppress BV-associated bacteria, we engineered Escherichia coli Nissle 1917 to locally acidify the vaginal environment. To test the efficacy of our strain in a realistic environment, we developed a chemically defined culture platform, VDK4, that mimics nutrient availability and the physiologically relevant pH buffering capacity within the cervicovaginal environment. Given that nutrient availability determines the bacterial community composition, we employed VDK4 to investigate how manipulating carbon sources could shift the nutrient landscape to favor a low-pH, Lactobacillus-dominated microbiome over a diverse, elevated-pH, BV-associated community. This work demonstrates the potential of synthetic probiotics for vaginal microbiome remediation while providing insight into how carbon availability shapes microbial community composition. By identifying nutrient interactions that selectively suppress BV-associated bacteria, these findings inform strategies to restructure the vaginal nutrient environment to promote stable, Lactobacillus-dominated communities.