Bacterial community profiling of plastic litter in the Belgian part of the North Sea

Bacterial colonization of marine plastic litter (MPL) is
known for over four decades. Still, only a few studies on the plastic
colonization process and its influencing factors are reported. In this
study, seafloor MPL was sampled at different locations across the
Belgian part of the North Sea to study bacterial community structure
using 16S metabarcoding. These marine plastic bacterial communities
were compared with those of sediment and seawater, and resin pellets
sampled on the beach, to investigate the origin and uniqueness of
plastic bacterial communities. Plastics display great variation of
bacterial community composition, while each showed significant
differences from those of sediment and seawater, indicating that
plastics represent a distinct environmental niche. Various environmental
factors correlate with the diversity of MPL bacterial composition across plastics. In addition, intrinsic plastic-related
factors such as pigment content may contribute to the differences in bacterial colonization. Furthermore, the differential
abundance of known primary and secondary colonizers across the various plastics may indicate different stages of bacterial
colonization, and may confound comparisons of free-floating plastics. Our studies provide insights in the factors that shape plastic
bacterial colonization and shed light on the possible role of plastic as transport vehicle for bacteria through the aquatic
environment.