Temporal Changes in Bacteriophage Communities and Predicted Metabolic Genes in Marine Plastisphere

To investigate the temporal dynamics and potential metabolic roles of bacteriophage communities in the marine plastisphere, we characterized phage community dynamics and phage-encoded auxiliary metabolic genes (AMGs) during a 21-day in situ experiment involving four plastic types. Phage communities differed significantly between the early (days 3–12) and late (days 15–21) stages, indicating distinct temporal shifts, whereas no significant differences were observed among polymer types. Changes in phage community composition in the plastisphere might be associated with bacterial host lineages. In particular, Vibrio phages were strongly associated with changes in host-Vibrios. In AMGs, nine metabolic categories comprising a total of nineteen detailed pathways were identified. AMGs associated with cofactor and vitamin metabolism were relatively enriched during the early stages, while sulfur-containing amino acid metabolism became more abundant during the late stages. These findings suggest that plastisphere-associated phages may be linked to microbial community succession and functional potential through dynamic host–phage associations.