Retrieving the real microbial diversity in aquatic plastisphere.

Area of Science:

• Marine microbiology
• Environmental science
• Microbial ecology

Background:

• Oceanic plastic debris forms a habitat for microbial communities, termed the plastisphere.
• Current methods for studying plastisphere microbial diversity may be flawed.

Purpose of the Study:

• To evaluate the impact of density-based separation on microbial diversity analysis of mesoplastics.
• To propose an improved methodology for preserving microbial diversity in plastisphere samples.

Main Methods:

• Scanning Electron Microscopy (SEM) for visualizing microbial structures.
• Microbiome analysis comparing density separation with and without prior chemical fixation.
• Quantification of microbial diversity and richness.

Main Results:

• Density-based separation significantly underestimates microbial diversity and richness.
• Chemical fixation (formaldehyde) prior to density separation preserves cellular diversity (2.32-fold change) and richness (1.12-fold change).
• Gram-negative bacteria are disproportionately affected by the omission of fixation; polymer composition has minimal impact.

Conclusions:

• Standard density-based separation methods are detrimental to accurate plastisphere microbiome studies.
• Incorporating formaldehyde fixation before density separation is crucial for preserving microbial diversity.
• This improved methodology will enhance understanding of marine microbial ecosystems and plastic-associated biofilms.