Microplastic-associated biofilms in lentic Italian ecosystems

Area of Science:

• Environmental Microbiology
• Ecotoxicology
• Polymer Science

Background:

• Microplastics are pervasive environmental contaminants.
• Microplastic-associated biofilms, termed the 'plastisphere,' represent a unique microbial habitat.
• Understanding the plastisphere's structure and function is crucial for assessing microplastic ecological impacts.

Purpose of the Study:

• To characterize the biodiversity and structure of microplastic-associated biofilms in Italian freshwater.
• To compare microbial communities on microplastics with planktonic communities.
• To investigate the influence of polymer type and degradation on biofilm composition.

Main Methods:

• 16S rRNA gene high-throughput sequencing for microbial community analysis.
• Fluorescence In Situ Hybridization (FISH) coupled with confocal laser scanning microscopy (CLSM) for in-situ visualization.
• Fourier Transform Infrared spectroscopy (FT-IR) and Scanning Electron Microscopy (SEM) for material analysis.

Main Results:

• Microbial communities on microplastics differed significantly from planktonic communities, indicating selective adhesion.
• A core plastisphere microbiome, including genera like Sphingorhabdus and Sphingomonas, was identified across samples.
• Microplastic degradation correlated positively with microbial biodiversity, with generalist taxa found on less degraded plastics.
• FISH-CLSM revealed Burkolderiaceae dominance, patchy colonization, and complex biofilm architecture.

Conclusions:

• The plastisphere harbors distinct microbial communities shaped by selective adhesion and microplastic degradation.
• Microplastic exposure time and degradation level are key factors influencing biofilm structure and diversity.
• The study provides novel insights into the ecological role of microplastics in freshwater environments.