Microplastic impacts archaeal abundance, microbial communities, and their network connectivity in a Sub-Saharan soil environment

Unmanaged plastic waste in Sub-Saharan Africa pollutes large areas and degrades into microplastics (MPs). Surfaces of MP are colonized by bacteria and fungi, resulting in the plastisphere. Plastispheres from high population hotspots on the African continent enrich pathogenic fungi, posing a potential threat to human health. Prokaryotes in such plastispheres are unknown to date. Thus, we analysed the prokaryotic microbiome of native plastisphere and soil by 16S rRNA gene amplicon sequencing, with a focus on community assembly mechanisms and putative pathogenic bacteria. A strong plastic-dependent depletion of archaeal ammonia oxidizing Nitrososphaeraceae was observed. Prokaryotic but not archaeal beta diversity significantly differed between plastisphere and soil microbiomes. The prokaryotic pathogenic potential in the plastisphere was marginally increased relative to soil, suggesting that MP is a driver for fungal rather than bacterial pathogens. Null model comparisons revealed a moderately stronger effect of deterministic selection events in the plastisphere than in soil. We observed a severe disruption of cooccurrence network connectivity in plastisphere communities in contrast to bulk soil communities. This study closes the knowledge gap on plastic debris in Sub-Saharan terrestrial environments, and the observed effects on archaea and cooccurrence networks suggest negative impacts on nitrification and stability of microbial communities.