Microbial inoculation simultaneously promotes humification and the removal of antibiotic resistance genes during kitchen waste composting

This research investigated the impact of microbial inoculation on humification and the dissemination of antibiotic resistance genes (ARGs) during kitchen waste composting. The findings showed that microbial inoculation (J) obviously facilitated the humification during composting, with the humic acid (HA) content increased by 12.11 % compared to the control (CK) without inoculation. The dissolved organic matter (DOM) of 3D-EEM spectrum showed that microbial inoculation promoted the humic-like substances formation and the degradation of soluble microbial byproducts. Random forest and correlation analysis indicated that increase in HA synthesis in J treatment during composting was attributed to the decomposition of fulvic acid (FA) and organic matter (OM). Moreover, microbial inoculation reduced the ARGs abundance, which decreased by 32.56 %, compared to CK. The random forest analysis and structural equation modeling illuminated that microbial inoculation prolonged thermophilic phase and reduced the abundance of mobile genetic elements (MGEs), therefore decreasing the prevalence of ARGs during composting. This research elucidated the potential mechanisms of microbial inoculation on HA formation, and revealed that the prolonged thermophilic phase promoted the removal of ARGs. It offers valuable insights for the simultaneous promotion of humification and the removal of ARGs during composting.