Time-dependent effects of microplastics on soil bacteriome

Area of Science:

• Environmental Science
• Microbiology
• Ecotoxicology

Background:

• Microplastic pollution is a growing global concern, yet its long-term ecological impacts remain poorly understood due to their inert nature.
• Investigating the effects of microplastics on soil microbial communities is crucial for assessing ecosystem health.

Purpose of the Study:

• To investigate the long-lasting ecological effects of six common microplastic types on soil bacteria.
• To understand how microplastics influence soil bacteriome structure, function, and genetic potential over time.

Main Methods:

• Soil microcosms were treated with six microplastic types (polyethylene, polypropylene, polyamide, polystyrene, polyethylene terephthalate, and polyvinyl chloride) at a 2% (w/w) concentration.
• Bacterial community structure and function were analyzed after one year of exposure.
• Model predictions were used to infer indirect effects of microplastics.

Main Results:

• Microplastic effects on soil bacteria converged after one year, differing significantly from short-term impacts.
• Specific microplastic-adapted bacteria (e.g., Actinobacteria) were enriched, while Bacteroidetes and Gemmatimonadetes declined.
• Bacterial communities showed enhanced capacity for xenobiotic and lipid metabolism but suffered from oxidative damage, impairing genetic information processing.
• Reduced organic carbon mineralization and increased microbial nitrogen requirements were observed.

Conclusions:

• Microplastic impacts on soil bacteria are primarily indirect, mediated by nutrient availability and oxidative stress.
• Microplastics exert stronger effects on bacterial functions than on community structure.
• The observed changes pose a significant risk to the functioning and health of soil ecosystems.