9 March, 2023

Sample analyses from 2021 and 2022 from native oysters from multiple sites in Europe uncovered multiple antibiotic resistance genes (ARGs) using target enrichment libraries last year. This activity from WP1 was the beginning of the search, which is continuing, using selected strains of oysters bred in France under different regimes of exposure to antibiotics, then distributed to all partners for use as sentinal animals at each European study site. This activity will aid to understand how microbial background can influence the acquisition of new strains in the oyster microbiome. New ARGs have been identified that were not previously known from the comprehensive antibiotic resitance database (CARD), and these will be studied further in the upcoming work  for 2023.

Recently in 2022, a major experiment was completed by marine scientist, Coralie Broquard from the Alfred Wegner Institute, Germany (the lead partner in the SPARE-SEA consortium), in which she ran duplicate multi-factorial experiments in different study sites among consortium members in Spain (IRTA), France (CNRS) and Germany (AWI) to investigate how environmental pollutants derived from terrestrial sources in each region might alter the enrichment of the microbiome and the concommitant accumulation of specific ARGs in the oyster habitat. This will help to open a window into understanding the drivers of ARG accumulation in the oyster habitat that may not be related specifically to the antibiotic residues from waste water.  Future work will identify in more detail the sources and sinks of the ARGs found in the oyster culture habitat and the surrounding environmental compartments. Samples to be analyzed include the resistome of bacteria from sediment, water, shellfish predators and other shellfish species found among oyster culture sites. This will be the work of WP4 in the coming year.

During all of this work, SPARE-SEA members have been abiding the regulations established for sanitary conditions related to the pandemic of COVID-19. These conditions entail that all  meetings have been online. Significantly, the consortium members enjoyed their first face-to-face meeting in December 2022 in Montpellier, France to discuss this and other works.

With new data comes new ideas and the future is looking good for SPARE-SEA partners.