Monsoon affects the distribution of antibiotic resistome in Tibetan glaciers.

Antibiotic-resistance gene (ARG) is a biological pollutant and is globally distributed due to increased anthropogenic activities. ARGs in the cryosphere have received increased attention due to global warming, and ARGs in glaciers are predicted to be released into downstream ecosystems during glacier melting. In this study, ARG distribution and influential factors were investigated in 85 samples from 21 Tibetan glaciers, covering snow, ice, and cryoconite habitats. The results revealed ARGs against 29 antibiotics in Tibetan glaciers, dominated by tetracycline, bacitracin, macrolide, and fluoroquinolone resistance. ARGs in snow exhibited biogeographic patterns influenced by atmospheric circulation. Specifically, monsoon-dominated glaciers exhibited a significantly higher abundance of ARGs than the westerly-dominated glaciers, which could be associated with higher antibiotic usage in the Indian subcontinent. Of the 3241 metagenome-assembled genomes obtained, 36.8% of which were identified as ARG hosts and 33.8% were multidrug-resistant. In addition, 90 ARGs were linked to mobile genetic elements (MGEs). 90.9% and 9.1% of MGEs were identified as plasmid and phage in 45 MAGs carrying both ARGs and MGEs. Our study suggests a greater risk of ARGs being released from the monsoon-dominated glaciers, which were the glaciers that melt at high rates and thus need to be carefully monitored.