Microbiome modulation of environmental contaminant concentrations in shellfish

Oysters are an important global seafood resource that provide nutrition, economic value, and ecosystem services for coastal communities. However, oysters also bioaccumulate environmental contaminants, including polycyclic aromatic hydrocarbons (PAHs) and human microbial pathogens such as Vibrio species, posing significant risks to human health. While environmental factors influencing contaminant levels in oysters are relatively well studied, the biological mechanisms that mediate contaminant and pathogen accumulation—particularly the role of the oyster microbiome— remain poorly understood. This project addresses critical knowledge gaps by testing the hypothesis that disruption of the oyster microbiome increases accumulation of PAHs and human pathogenic Vibrio species. We predict that these outcomes will be linked to loss of protective or contaminant-degrading microbial taxa, reduced microbial diversity, and impaired host health. Two specific aims will test this hypothesis: (1) Determine how microbiome disturbance affects phenanthrene levels in oysters, and (2) Characterize how microbiome disturbance influences concentrations of Vibrio vulnificus and V. parahaemolyticus. Phenanthrene is a commonly studied model PAH that shares structural similarities with highly toxic PAH compounds, is relevant to human health, and is frequently detected in oyster tissues. V. vulnificus and V. parahaemolyticus are the most common and clinically important pathogens associated with oyster consumption. Experimental approaches will include antibiotic-induced microbiome perturbation, contaminant and pathogen quantification, 16S rRNA gene sequencing, and oyster physiological stress assays. This research will provide novel mechanistic insight into how oyster microbiomes influence seafood safety and human exposure to environmental contaminants. In addition, the project will fully integrate undergraduate students into an interdisciplinary research program, providing hands-on training that will enhance student development and support the NIH mission by strengthening biomedical research capacity and workforce potential at an undergraduate-focused institution. Project Number: 1R15ES038670-01 | Fiscal Year: 2026 | NIH Institute/Center: National Institute of Environmental Health Sciences (NIEHS) | Principal Investigator: Rachel Diner | Institution: UNIVERSITY OF MEMPHIS, MEMPHIS, TN | Award Amount: $506,270 | Activity Code: R15 | Study Section: Environmental Determinants of Disease Study Section [EDD] View on NIH RePORTER: https://reporter.nih.gov/project-details/11360974