Urbanization enhances consumer protist-driven ARGs dissemination in riverine ecosystems

Area of Science:

• Environmental microbiology
• Ecotoxicology
• Genomics

Background:

• Antibiotic resistance genes (ARGs) and antibiotic resistant bacteria (ARBs) pose a global health threat.
• The influence of watershed urbanization on inter-trophic interactions and the aquatic resistome is poorly understood.

Purpose of the Study:

• To investigate how urbanization and inter-trophic interactions shape the aquatic resistome.
• To differentiate the roles of mobile versus non-mobile ARGs in urbanized environments.

Main Methods:

• Metagenomic and amplicon (16S and 18S rDNA) sequencing of water samples from urbanized and less-urbanized tributaries.
• Analysis of relationships between microeukaryotic algae, consumer protists, bacterial communities, and the resistome.
• Structural equation modeling to identify key inter-trophic drivers.

Main Results:

• Mobile ARGs showed greater discrepancies between tributaries than non-mobile ARGs.
• The highly urbanized tributary had higher ARG abundance and more shared ARGs between pathogens and non-pathogens.
• Consumer protist-bacteria interactions dominated the resistome in the urbanized tributary, while algae-bacteria interactions were key in the less-urbanized tributary.

Conclusions:

• Watershed urbanization distinctly alters inter-trophic interactions that drive the aquatic resistome.
• Consumer protists and algae play differential roles in the dissemination of ARGs, particularly mobile ARGs, depending on urbanization levels.