BayCEER Workshop 2023

12 October 2023

The buried threat below? - Investigating the impact of microplastics on rhizosphere microbial communities in agricultural plants

Aileen Jakobs¹, Ryan Bartnick², Eva Lehndorff², Tillmann Lueders¹

¹ University of Bayreuth, Chair of Ecological Microbiology, Bayreuth Center of Ecology and Environmental Research (BayCEER), Bayreuth, Germany
² University of Bayreuth, Chair of Soil Ecology, Bayreuth Center of Ecology and Environmental Research (BayCEER), Bayreuth, Germany

P 3.4 in Zooming in: Small scale findings

Microplastics (MP) are serious contaminants of arable soils, mostly introduced by agricultural practices or unintentional dispersal. Therefore, a comprehensive understanding of MP-induced effects on soil processes is urgently needed to derive consequences for crop production.
In the rhizosphere, root-associated microorganisms fulfill crucial functions to promote plant growth and maintain plant health. Our study aims to give insights on the impacts of MP on microbial communities and microbially mediated biogeochemical processes in the rhizosphere of two different agricultural plants.
We conducted a controlled greenhouse experiment with maize (Zea mays) and strawberries (Fragaria × ananassa), grown in soils spiked with MP particles (75-400 µm) to assess the influence of MP on plant growth, soil properties, and microbial communities. Plants were exposed to either conventional (low-density polyethylene, LDPE; poly(ethylene terephthalate), PET; polystyrene, PS) or biodegradable (poly(butylene adipate-co-terephthalate), PBAT) MP at 1% w/w for three months. In our ongoing work, the microbial community composition is elucidated by state-of-the-art 16S rRNA gene and ITS metabarcoding. The activity of selected soil enzymes relevant for carbon and nutrient cycling is assessed with fluorometric 4-methylumbelliferyl (MUF)-based enzyme assays. Root colonization with arbuscular mycorrhizal fungi is estimated via a microscopy approach.
Our first results indicate that MP did not significantly affect aboveground plant growth and root colonization with arbuscular mycorrhizal fungi throughout our trial. However, microbial communities tend to be more responsive to biodegradable than conventional plastics in bulk soils. We are currently evaluating whether this trend extends to rhizosphere soil communities. Ultimately, the findings of this study will add to our comprehension of the impacts of MP on soil microbial communities and the potential implications for agroecosystems.