Comparison of the plastisphere and surrounding waste in landfills: Bacterial community assembly and functional...

Plastic waste in landfills forms unique microbial habitats termed the plastisphere, a critical but underexplored niche in anaerobic, dark landfill environments. To advance plastisphere research in such terrestrial anaerobic settings and inform landfill management, this study employed an integrated approach of 16S rRNA sequencing and metagenomics to systematically investigate the bacterial community structure, assembly mechanisms, and metabolic functions of the plastisphere. Network analysis indicated that the plastisphere sustains a simplified yet highly modular co-occurrence network shaped by competitive niche partitioning. The plastisphere and surrounding waste exhibited no overlap in network keystone taxa. Key plastisphere taxa-including g_Devosia, g_Rummeliibacillus, and g_Dethiobacter-demonstrated enhanced carbon utilization and stress perception capabilities, playing crucial roles in community assembly and plastic degradation. Although stochastic processes dominated community assembly (73.75 %), homogeneous selection (HoS) driven by plastic properties and keystone taxa enriches pathogens (e.g., Microbacterium spp.) and nitrogen-cycling (e.g., Pseudohongiella) guilds. Metagenomic analysis confirmed the enrichment of denitrification (narB, nosZ) and sulfite reduction (sir, cysCDHIJN) genes, indicating elevated risks of N₂O and H₂S emissions, especially during early landfill stabilization. Redundancy analysis identified pH, biodegradable organic matter (BDM), and total Kjeldahl nitrogen (TKN) as key environmental drivers. These findings establish the landfill plastisphere as a reservoir of plastic-degrading and potentially pathogenic microorganisms, with important implications for greenhouse gas emissions, odor control, and landfill management strategies. This study provides foundational insights into the ecological consequences of anthropogenic microhabitats in terrestrial environments, bridging critical knowledge gaps in plastisphere ecosystems within landfills-an anaerobic, dark environment rich in organic matter.