Plastics are offering a new niche for microorganisms colonizing their surface, the so-called ‘plastisphere’, which diversity and community structure remain to be characterized and compared across ocean pelagic regions. We compared the bacterial diversity of organisms living on marine plastic debris (PMD) and the surrounding free-living (FL) and organic particle-attached (PA) fractions sampled during the Tara expeditions in two of the most plastic polluted zones in the world Ocean, i.e. the North Pacific gyre (this study) and the Mediterranean Sea (already published).