Role of traveling microplastics as bacterial carriers based on spatial and temporal dynamics of bacterial communities

Microplastics (MPs) are considered as distinct substrates for bacterial colonization, they can carry bacterial communities to travel around environments. The bacterial communities on traveling MPs prefer to be gradually consistent with those on local MPs that were always in the same environment, and this process of change in the bacterial communities on traveling MPs was called 'localization'. However, the dynamics of localization process and their influencing factors are still unclear. Therefore, we simulated the MPs migration process along the water flow direction in the estuary. We used quantitative analysis to study the dynamics of bacterial communities on the migrated MPs. We found the localization characteristics depended on the differences between the former and latter environments, as well as the preexisting bacteria. The localization degree was higher when the former and latter environments were similar. In most cases, compared with the first cultivation of pristine MPs, the time for localization was shorter. Moreover, although the entire bacterial communities tended to be localized, the preexisting bacteria on the migrated MPs had selective effects on subsequent bacterial colonization. Furthermore, the preexisting bacteria on MPs could set up the connections with the bacteria that existed at the latter site, and the stability of the entire bacterial communities on the migrated MPs increased with time. Overall, our findings indicated that the localization characteristics of bacterial communities on traveling MPs were related to the precultured time and environmental differences, which were helpful to understand the colonized bacteria transportation and MPs ecological effects.