Key species reduces antibiotic resistance genes in food waste composting via enhanced cooperation potential and...

Antibiotic resistance genes (ARGs) often persist or rebound after food waste (FW) composting. Key species (Thermobifida fusca and Saccharomonospora viridis) are considered a promising strategy for mitigating ARGs by strengthening cooperation potential. However, their effects on ARGs dynamics during composting remain unclear. To address this, three composting treatments were conducted: inoculation with both key and functional species (TA), inoculation with functional species only (TB), and an uninoculated control. Compared with Control, TA significantly prolonged the thermophilic period by 3.4 times and increased the humification rate by 1.3 times. After composting, TA exhibited a 55.1% reduction relative to the initial relative abundance before composting, reaching 0.39 copy/cell. In contrast, the relative abundance of total ARGs increased by 1.3-fold in the Control (0.62 copy/cell). Moreover, TA exhibited a reduction in mobile ARGs from 0.19 to 0.08 copy/cell, whereas the Control increased from 0.11 to 0.16 copy/cell, and TB remained relatively stable (∼0.16-0.17 copy/cell). These key species successfully colonized in TA, with relative abundances 20.0-158.7 times higher than that in Control, and were identified as key hubs in networks, enhancing the proportion of positive edges by 1.2 times. Overall these results suggested that introducing key species into a functional inoculum was associated with enhanced potential positive associations, improved humification, and reduced diversity, relative abundance, and mobility of ARGs.