Culturing the Plastisphere: comparing methods to isolate culturable bacteria colonising microplastics

Area of Science:

• Environmental microbiology
• Materials science

Background:

• Microplastics host microbial communities (Plastisphere).
• Concerns exist about microplastics spreading pathogens and antimicrobial resistance.
• Current research lacks conclusive evidence on microplastics' unique role due to method limitations.

Purpose of the Study:

• To compare the efficiency of four common biofilm extraction methods.
• To optimize culture-based methods for studying the Plastisphere.
• To determine the best method for culturing bacteria from microplastics and control particles.

Main Methods:

• Compared swabbing, sonication, vortexing, and sonication-vortexing for biofilm removal.
• Used microplastics (polyethylene, polypropylene, polystyrene) and control particles (wood, glass).
• Assessed extraction efficiency using CFU/mL, optical density, and 16S rRNA qPCR.

Main Results:

• All tested methods removed biofilms with varying efficiencies.
• Sonication with glass beads (15 min) followed by vortexing (1 min) yielded the highest number of culturable bacteria.
• This combined method demonstrated the greatest removal efficiency for biofilm-forming bacteria.

Conclusions:

• Optimized culture-based methods are crucial for Plastisphere research.
• Sonication and vortexing combination is highly effective for bacterial extraction from microplastics.
• This improved methodology can help clarify microplastics' role in microbial spread.