Endospore DNA as a proxy of antibiotic resistance genes in sediments of Lake Geneva

BAYRYCHENKO, Z. ; PAUL, C.; MADUEÑO, L.; BECK, K.; BUERGMANN, H.; JUNIER, P.

Berna

Simposio; SSM Annual Assembly and Meeting; 2016

Antibiotics resistance in pathogenic microbes is a pressing problem worldwide. Research over the lastdecades has shown that aquatic environments play a role as reservoir of antibiotic resistance genes(ARG) and thus as a pathway of dissemination of resistant organisms (1). There is also evidence of cooccurrenceof ARG and heavy metals in aquatic sediments (2), but the reason for this is still unknown.Vidy Bay in Lake Geneva (Switzerland) receives treated and partly untreated sewage from the city ofLausanne, which results in high levels of sediment contamination. Previous studies have shown thatLake Geneva sediments are polluted with multi-resistant bacteria and ARG (3), as well as with heavymetals (4). Therefore these sediments are ideal to investigate the co-occurrence of ARG and heavymetals. Also the sediments with the highest levels of heavy metal contamination are enriched withClostridium spp (4), which are endospore-forming Firmicutes commonly found in the human intestinaltract. Endospores are very resistant cell forms able to survive harsh environmental conditions. Unliketotal bacterial DNA, which decreases with depth, endospore DNA remain constant with depth (5). Theaims of our study are to assess the potential of endospores as proxies to the spatial-temporaldistribution and to the origin of ARG in lake sediments. In addition, the link between the distribution ofARG and heavy metals with regards to endospores will be analyzed. Our preliminary analysis hasshown that ARG tetW and sul1 are detected in endospore-DNA and that compared to the total DNA,endospore-DNA is enriched on ARG. We hypothesize that endospores are key organisms to understandthe co-occurence of ARG and heavy metals in the environment and that they could clarify the origin ofARG in lake sediments. We are currently evaluating the distribution of tetW and sul1 genes inendospore-enriched DNA extracted from Lake Geneva sediments contaminated with heavy metals.