Résumé
Although the existence of a plastisphere harboring potential fish and human pathogens has been highlighted on plastic debris, the microbiological consequences of microplastics ingestion and the potential bacterial transfer mechanisms, remain unknown. In this study, we set up an original ex situ experiment to examine the transfer of a cultivable human model pathogen, E. coli, from colonized PET fragments (500-1600 µm) to the gut and organs of the rabbitfish (Siganus sutor), a species of high commercial and aquaculture interest in the South-west Indian Ocean. Our findings show that the PET fragments were efficiently ingested by the fish with a retention time up to 120 hours post-exposure. Microplastic-associated E. coli ingestion resulted in the transfer of cultivable E. coli to the digestive tract of fish – a phenomenon not observed in fish exposed to free E. coli in seawater. Additionally, detectable and/or cultivable E. coli were detected in the muscle, gill, liver, and heart after 24h of exposure but at very low levels and infrequent occurrence. These experimental results provide the first direct evidence of bacterial transfer from MPs to the fish gut, confirming that MP could act as fomites for pathogen bacteria in fish populations, and ultimately pose a risk to human consumers relying on seafood.