Influence of aquaculture and genomic surveillance techniques on antimicrobial resistance gene profiles and microbiota detected in marine and freshwater sediments

Surveillance methods for antimicrobial resistance genes (ARGs) are needed to assess potential risk of antimicrobial resistance, especially in complex environmental samples with limited data on ARG distribution. This study employed target-enrichment metagenomics (bait-capture) and a Resistomap qPCR assay to assess the resistome in marine and freshwater sediments associated with active Canadian finfish aquaculture operations. Differences in resistome profiles were considered with distance to the net-pens, concentrations of three aquaculture-associated chemical residues, and microbial communities as detected with 16S rRNA gene amplicon sequencing. With bait-capture, a total of 194 ARGs and 41 replicon types were detected across the sediment samples. Differences due to aquaculture proximity were noted in the composition of the resistome, which was dominated by tetracycline resistance genes. With qPCR, 37 out of 51 ARGs targets were detected, and proximity to net-pens or region did not show changes in resistome composition. Co-occurrence networks revealed significant correlations among genera and the resistome detected with bait-capture, highlighting a potential influence of aquaculture on ARGs in the environment. This study demonstrates the utility of bait-capture and qPCR assays in detection of ARGs in both freshwater and marine sediments from aquaculture sites that will assist further ARG surveillance.