A competitive colonization-based isolation workflow for recovering motile bacteria from marine plastisphere

After one application, the CCIW yielded 94 non-redundant isolates affiliated with 30 genera across five phyla (classes). In addition to commonly reported MP-associated genera, such as Vibrio and Pseudomonas, the collection included seven genera rarely recovered from marine plastisphere, 21 putative novel species, and 13 actinobacterial strains. Genome analysis showed that 75 strains (79.8%) carried motility-associated genes involved in flagellar, chemotaxis, or pilus.

Plate-based assays confirmed motility in 72 isolates, with 68 and 60 strains exhibiting swimming and twitching motility, respectively, highlighting the effectiveness of CCIW in recovering motile bacteria. Swimming and twitching diameters were strongly positively correlated, and seven genera, including Agarivorans and Photobacterium, contributed most of strongly motile strains. Leifson staining further verified flagella in representative swimming strains.