16S rRNA Gene Sequence Analysis of the Microbial Community on Microplastic Samples from the North Atlantic and Great Pacific Garbage Patches

Abstract

Marine plastic debris represents a relatively new and increasingly abundant substrate for colonization by microbial organisms, although the total functional potential of these organisms is yet to be uncovered. The exponential increase of plastic production has led to their subsequent accumulation in the environment, particularly in oceans, as current conventional treatments of plastic waste are of minimal efficiency. In the present study, we compared microbial communities on plastic, known as "Plastisphere", from the Atlantic and Pacific oceans to see whether they were significantly distinct. In addition, we identified potential plastic degraders within these Plastispheres. Therefore, we used 16S rRNA amplicon analysis on microplastic and water samples collected in the Great Pacific and North Atlantic Garbage Patches, respectively, in June and August 2019 and literature review. Four polymer types composed the plastics: high-density polyethylene (HDPE), linear low-density polyethylene (LDPE), polypropylene (PP) and polyethylene (PE). We found that microbial communities differed significantly between the two oceans. We identified thirty-two differentially abundant taxa at the class level between the two oceans. We also found that communities living on plastic polymers in the Atlantic and the Pacific are not significantly distinct within each area, along with communities living in water and plastic in the Pacific. Proteobacteria, Cyanobacteria and Bacteroidota were the most prominent relative abundant phyla on the three substrates. Finally, we found 40 genera belonging to the phyla Actinobacteriota, Bacteroidota, Firmicutes and Proteobacteria within the Plastisphere, documented in the literature as potential plastic degraders. We ended the work with recommendations for future studies, notably the integration of the properties of both oceans like temperature, dissolved oxygen, salinity and pH to determine likely drivers of these differences in communities' colonization.