Polymers and immersion time shape bacterial pathogen and antibiotic resistance profiles in aquaculture facilities

Most equipment used in aquaculture farms is made of plastic. Plastics-associated biofilms may contain potential human pathogenic bacteria (PHPB) and antibiotic-resistant bacteria (ARB). Understanding the influence of farming practices on the biofouling development and composition is thus essential to control associated microbiological risks. We combined results from metabarcoding analyses, bacterial cultures, and antibiotic susceptibility testing to compare the bacterial pathobiome and resistome associated with plastic aquaculture equipment, including two polyamide nets and a polyester liner, with those associated to a hemp net and a glass control. Over the 3 months of incubation in an aquaculture farm, plastics exhibited neither higher levels of PHPB nor more multiple antibiotic resistance compared to other solid substrates, but they did present specific PHPB and ARB profiles. Bacterial members of the Vibrionaceae and Staphylococcaceae families were more abundant in plastic PHPB communities (respectively 47% and 22% of PHPB reads) than in other substrate ones (4% and 0.22% of PHPB reads). The plastic-associated antibiotic resistance profiles showed higher resistance against quinolones. These results suggest that aquaculture equipment could act as a reservoir for some PHPB and ARB, and that equipment composition and immersion time could be levers to control associated sanitary risks.