Microplastic (MP) accumulation in constructed wetlands potentially threatens sulfur-autotrophic denitrification under low C/N conditions, yet the resilience of plastisphere-derived denitrifiers remains poorly understood. Here, we isolated and compared two denitrifying strains, a plastisphere isolate, Stutzerimonas balearica SP-H, and a conventional wetland isolate, Castellaniella denitrificans S0-H, under polyamide (PA) and polyethylene (PE) MP exposure. MPs severely impaired strain S0-H, causin