Retrieving the real microbial diversity in aquatic plastisphere.

Disposed plastics in oceans provide a substrate to which microbes can adhere and structure the biofilm, namely the plastisphere. In this study, we showed that the mesoplastic density-based separation, routinely used in quantification assays, is detrimental to studying the microbiome diversity and ecology as it underestimates the real microbial diversity within these samples. Based on SEM and microbiome observations, we propose that chemically fixing samples before density separation preserves cellular diversity (2.32-fold change) and richness (1.12-fold change) that would be naturally lost due to the current methodology. OTUs assigned to Gram-negative bacterial species are the most negatively affected by omitting fixation and polymer composition was not decisive in shifting microbiome composition. Considering our findings, the formaldehyde-fixation step should be incorporated into the current methodology described in most studies as this is crucial to promote a deeper understanding of the microbial community in this ecosystem and biofilm-adhered scattering through aquatic ecosystems.
Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Fernanda de Avila Abreu reports financial support was provided by the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq). If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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