Passively aerated static composting is widely adopted for livestock manure treatment; however, its efficacy in eliminating antibiotic resistance genes (ARGs) and pathogens is often inadequate due to ineffective oxygen diffusion to restrict organic biodegradation and thus the formation of thermophilic condition. Despite extensive research on aerobic composting, the optimal amendment strategy and mechanistic role of crop stalks in shaping ARG dynamics during passively aerated static composting of swine manure remain unclear. Here, cornstalks and swine manure were representatively selected to elucidate how their passively aerated static composting was successfully initiated to improve ARG elimination using genome-resolved metagenomics and multivariate statistical analysis. Results show that adding 10% cornstalks significantly enhanced antibiotic resistome removal by improving composting properties (e.g. moisture content and oxygen permeability) and increasing temperature (above 65 °C). This improvement effectively inactivated bacterial hosts of ARGs and restrict horizontal gene transfer (HGT). Under these conditions, cornstalk addition promoted thermal inactivation of ARG hosts (e.g. Actinomycetota), particularly pathogenic antibiotic-resistant bacteria (e.g. Corynebacterium), thereby suppressing HGT. More importantly, chromosomally encoded mobile genetic elements (rather than plasmids and viruses) dominated HGT during composting. The transfer of multidrug, bacitracin, and macrolide-lincosamide-streptogramin resistance genes was primarily facilitated by intra-phylum HGT events, particularly within Bacillota. Cornstalk addition significantly accelerated inactivation of pathogens and ARG hosts (e.g. macrolide-lincosamide-streptogramin resistant bacteria), resulting in an increased removal of over 49.0% for both. These findings provide mechanistic insights into the optimization of passively aerated static composting for safe agricultural reuse of livestock manure.
Xia et al. (2026) studied this question.