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While the distribution of extracellular ARGs (eARGs) in the environment has been widely reported, the factors governing their release remain poorly understood. Here, we combined multi-omics and direct experimentation to test whether the release and transmission of eARGs are associated with viral lysis and heat during cow manure composting. Our results reveal that the proportion of eARGs increased 2.7-fold during composting, despite a significant and concomitant reduction in intracellular ARG abundances. This relative increase of eARGs was driven by composting temperature and viral lysis of ARG-carrying bacteria based on metagenome-assembled genome (MAG) analysis. Notably, thermal lysis of mesophilic bacteria carrying ARGs was a key factor in releasing eARGs at the thermophilic phase, while viral lysis played a relatively stronger role during the non-thermal phase of composting. Furthermore, MAG-based tracking of ARGs in combination with direct transformation experiments demonstrated that eARGs released during composting pose a potential transmission risk. Our study provides bioinformatic and experimental evidence of the undiscovered role of temperature and viral lysis in co-driving the spread of ARGs in compost microbiomes via the horizontal transfer of environmentally released DNA. [ABSTRACT FROM AUTHOR]

A total of 247 Escherichia coli isolates (148 from diseased or dead poultry and 99 from diseased pets in the People's Republic of China) were screened for extended-spectrum β-lactamase (ESBL) determinants by PCR and sequencing. Then, 16S rRNA methylase genes were detected among ESBL-producing isolates. Clonal relatedness of the E. coli isolates was examined by pulsed-field gel electrophoresis. Conjugation experiments were performed to investigate the association of 16S rRNA methylases and ESBLs, and plasmid contents were also characterized. Among 247 E. coli isolates, 74 (29.96%) isolates were positive for blacTX-M genes, 42 from pets (12 from cats and 30 from dogs) and 32 from poultry (12 from chickens and 20 from ducks). The most common CTX-M type in isolates from pets was blaCTX-M-14, whereas blaCTX-M-27 was the most common for poultry, rmtB was dectected in 39 of the 74 blaCTX-M-positive isolates, 18 from pets and 21 from poultry. One strain from a pet was found to harbor blaCTX-M-I4, blaCTX-M-15, and rmtB. blaCTX-M and rmtB were found to be colocated on the same transferable plasmid in 16 isolates. These genes were on the same or similar plasmids (eight F2:A-:B- and two IncN) in isolates from ducks, whereas they were colocated on the similar F2:A-:B- or similar F33:A-:B- plasmids in isolates of pets origin. In conclusion, similar F2:A-:B-plasmids and similar F33:A-:B- plasmids are responsible for the dissemination of both rmtB and blacTX-M genes in E. coil isolates from poultry and pets, respectively. [ABSTRACT FROM AUTHOR]