Biomicroplastics and Antibiotics: A Toxic Cocktail for Fatty Liver Disease in Marine Medaka

The increasing production and use of bioplastics contribute
to
the accumulation of bioplastic debris in marine environments. The
impact of such debris, particularly when combined with co-occurring
pollutants like antibiotics, on marine life remains largely unexplored.
In this study, we demonstrate that coexposure to aged polylactic acid
(PLA) biomicroplastics and the antibiotic sulfamethazine (SMZ) induces
overweight (an increase of 20.9–26.2%) and fatty liver-like
disease in juvenile marine medaka (Oryzias melastigma). We investigated the underlying mechanism involving the orchestration
of physiological processes between the host and its gut microbiota.
We found that SMZ acted as a precondition or driver, while PLA acted
as an environmental selective pressure, directionally shaping the
gut microbiota communities. This altered microbiota demonstrated an
increased ability to break down PLA into lactic acid, activating intestinal
gluconeogenesis and consequently generating glucose. Excessive glucose
shifted the hepatic glucose-fat balance toward fat accumulation, resulting
in triglyceride and lipid droplet accumulation and overweight in the
fish. Given the prevalent co-occurrence and interaction of PLA and
antibiotics in the real-world environment, the combined ecological
risk posed by these pollutants requires further investigation.