Antibiotic resistance gene load and irrigation intensity determine the impact of wastewater irrigation on antimicrobial resistance in the soil microbiome

, tet(M) and intI1 correlated with TWW irrigation intensity and decreased during irrigation breaks. Despite the decrease, the levels of these genes remained consistently higher than the non-irrigated soil indicating persistence upon their introduction into the soil. Microcosm experiments verified observations from the field study: TWW irrigation promoted the spread of ARGs and intI1 into soil at far elevated levels compared to FW irrigation. However, the impact of TWW irrigation on 16S rRNA absolute abundance and the soil microbial community composition was negligible. In conclusion, the impact of TWW irrigation depends mainly on the introduced ARG load and the irrigation intensity.