Dynamics of antibiotic resistance genes and the bacterial community after stress from a single Dazomet fumigation

Although chemical fumigants are widely applied in agriculture to control soil-borne diseases, their influence on soil antibiotic resistance genes (ARGs) remains poorly understood. This study employed metagenomic sequencing to investigate the dynamic response and recovery processes of soil bacterial communities and ARGs after the end of fumigation with Dazomet. The results revealed that the effects of Dazomet were both phased and recoverable. Initially, no significant shifts in bacterial community diversity were observed; however, by day 10 of recovery (Dazomet10), diversity had decreased by 3.1 %. By contrast, ARG levels surged by 17.3 % and 10.9 % on days 10 and 20 (Dazomet20), respectively, before reverting to the baseline by day 50 (Dazomet50). These patterns were corroborated by qPCR data, which showed a 90.8 % reduction in 16S rRNA gene abundance, alongside a 4.17- to 4.38-fold increase in the relative abundance of ARGs at Dazomet10 and Dazomet20. Approximately 63 % of the variation in ARGs was attributed to bacterial community composition and mobile genetic elements (MGEs). Combined with community analysis and host-tracking analysis, it was found that Streptomyces and Nocardioides were identified as key ARGs hosts. Overall, the microbial communities and resistome required at least 50 days after the end of fumigation to recover to their pre-fumigation state. This study sheds light on the dynamic interactions between bacterial communities and ARGs during recovery from Dazomet fumigation and underscores the critical need for the rational use of fumigants in agricultural practices.