Dynamics of the plastisphere microbiome in agricultural soils under changing climatic conditions

Plastic pollution is a growing environmental concern, particularly in agricultural soils where plastics are widely used. Biodegradable plastics such as polybutylene succinate (PBS) and polybutylene adipate-co-terephthalate (PBAT) are increasingly promoted as sustainable alternatives, yet their environmental fate under changing climate and land-use conditions remains poorly understood. This study investigated the plastisphere microbiome associated with PBS, PBAT, and polyethylene (PE) as a reference, under conventional and organic farming systems and both ambient and simulated future climate scenarios. We assessed microbial colonization, plastic degradation, and bacterial-fungal interactions over one year of soil exposure. Agricultural practices significantly influenced the PBS plastisphere microbiome and PBAT bacterial richness, while climate effects were minor and limited to specific time points. No treatment significantly affected the molar mass loss of biodegradable plastics, although PBS degraded faster than PBAT. Microbial community composition shifted over time, with bacterial and fungal richness peaking at 160 or 270 days, and gene copy numbers highest at 60 or 365 days. Early colonization was dominated by a few genera, including Sphingomonas, Hymenobacter, Massilia, Vishniacozyma, Alternaria, and Mycosphaerella, many of which are known plastic colonizers and potential degraders. Co-occurrence networks revealed positive associations between dominant bacterial and fungal taxa. These findings provide new insights into the temporal dynamics and environmental drivers of plastisphere microbiomes in agricultural soils. Understanding microbial succession and interactions on biodegradable plastics is essential for assessing their degradation potential and environmental risks, particularly regarding microplastic formation and the persistence of plastic residues in terrestrial ecosystems.