Impacts of microplastics on rhizosphere microbiome structure and function: a systematic review

Area of Science:

• Environmental Science
• Microbiology
• Soil Science

Background:

• Microplastic (MP) contamination is a growing environmental concern in agricultural soils.
• The rhizosphere microbiome is crucial for plant health and soil fertility.
• MPs pose a potential stressor to these vital soil ecosystems.

Purpose of the Study:

• To systematically review and synthesize existing research on microplastic impacts on rhizosphere microbial communities.
• To evaluate the effects of different microplastic types, concentrations, and co-stressors on soil microbial structure and function.

Main Methods:

• Systematic literature review of 32 primary studies.
• Analysis of reported changes in microbial alpha and beta diversity.
• Examination of impacts on specific microbial guilds and functional genes.

Main Results:

• Microplastics consistently alter microbial community structure, significantly shifting beta diversity.
• Effects on alpha diversity are context-dependent, with both decreases and increases reported.
• Biodegradable microplastics (BMPs) cause significant disruptions, comparable to or exceeding conventional polymers, affecting nutrient cycling genes and beneficial microbes like plant growth-promoting rhizobacteria (PGPR).

Conclusions:

• Microplastic contamination significantly alters soil microbial communities, with potential negative consequences for plant nutrient acquisition and stress resilience.
• Current evidence, largely from high-dose, short-term studies, raises concerns but cannot definitively predict long-term agricultural sustainability.
• Further field-relevant, long-term research is essential to fully assess the ecological risks of microplastics in terrestrial ecosystems.