Microplastic-colonizing communities like everything to be just right, when deciding to settle down

The global distribution of microplastics in the marine environment has been of popular interest to the scientific community recently and it is now apparent that biogeography plays an important role for the composition of microplastic colonizing communities. In a two week, in situ incubation experiment, Oberbeckmann et al. (2018) investigated how the composition and specificity of bacterial communities that colonise on natural and synthetic substances differ along an environmental gradient in the Baltic Sea. Plastic-specific assemblages were found via high-throughput sequencing, developing solely under certain conditions, including lower nutrient concentrations and higher salinities. One genus that was more abundant on plastic in areas of increased nutrients than on any other material tested was Sphingomonadaceae, which is known to be a reservoir for antibiotic-resistance. 

This study provides evidence that microplastic specific marine microbiomes exist and are dependent on ambient environmental conditions. This has ecological significance, particularly in microplastic-associated bacterial populations in plastic accumulation zones, as the potential for microplastics to be a hotspot for the transport and transfer of antibiotic resistance has not been investigated as of yet, and may be of great importance. One shortcoming of this study was that data to assess both communities (free living and attached) was only collected at a two-week timepoint; there was no measure of what happened during the initial few hours or days, which previous research suggests it is important in subsequent community recruitment.

Oberbeckmann, S., Kreikemeyer, B., & Labrenz, M. (2018). Environmental factors support the formation of specific bacterial assemblages on microplastics. Frontiers in microbiology, 8, 2709. This article can be found at: https://www.frontiersin.org/articles/10.3389/fmicb.2017.02709/full