Enhanced Fish Feeding Tendency toward Poly(vinyl chloride) Microplastics Colonized by Luminescent Bacteria

Luminescent bacteria can colonize the surfaces of microplastics (MPs), where the bacteria emit light, potentially promoting fish feeding tendency to MPs. The present study evaluated biofilm formation and bioluminescence of a marine bacterium on poly(vinyl chloride) MPs and examined the predative behavior of fish Sphaeramia nematoptera toward glowing and nonglowing MPs. Biofilm formation was significantly higher on UV-aged MPs than on pristine MPs, ethanol-washed MPs, and silica sand. Microplastics and their leachates enhanced the bioluminescence of the bacteria with maximum increases of 60% and 70% for pristine and UV-aged MPs, respectively, primarily driven by Ca2+ release. Behavioral assays showed that fish preferentially fed on glowing MPs, indicating that bioluminescence enhanced the visibility and attractiveness of MPs. These findings suggest that interactions between MPs and luminescent bacteria may boost the tendency of fish to feed on MPs, raising concerns about their potential accumulation in marine food webs.