title: Constitutive presence of antibiotic resistance genes within the bacterial community of a large subalpine lake.
abstract: The fate of antibiotic resistance genes (ARGs) in environmental microbial communities is of primary concern as prodromal of a potential transfer to pathogenic bacteria. Although of diverse origin, the persistence of ARGs in aquatic environments is highly influenced by anthropic activities, allowing potential control actions in well-studied environments. However, knowledge of abundance and space-time distribution of ARGs in ecosystems is still scarce. Using quantitative real-time PCR, we investigated the presence and the abundance of twelve ARGs (against tetracyclines, β-lactams, aminoglycosides, quinolones and sulphonamides) at different sampling sites, depths and seasons, in Lake Maggiore, a large subalpine lake, and in the area of its watershed. We then evaluated the correlation between each ARG and a number of ecological parameters in the water column in the deepest part of the lake. Our results suggest the constitutive presence of at least four ARGs within the bacterial community with a high proportion of bacteria potentially resistant to tetracyclines and sulphonamides. The presence of these ARGs was independent of the total bacterial density and temperature. The dynamics of tet(A) and sulII genes were, however, positively correlated with dissolved oxygen and negatively to chlorophyll a, suggesting that the resistant microbes inhabit specific niches. These observations indicate that the lake is a reservoir of antibiotic resistances, highlighting the need of a deeper understanding of the sources of ARGs and the factors allowing their persistence in waters.
authors.affiliation: Microbial Ecology Group, National Research Council - Institute of Ecosystem Study (CNR-ISE), Largo Tonolli 50, 28922, Verbania, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Di Cesare
authors.affiliation: Microbial Ecology Group, National Research Council - Institute of Ecosystem Study (CNR-ISE), Largo Tonolli 50, 28922, Verbania, Italy.
authors.forename: Ester M
authors.initials: EM
authors.lastname: Eckert
authors.affiliation: Microbial Ecology Group, National Research Council - Institute of Ecosystem Study (CNR-ISE), Largo Tonolli 50, 28922, Verbania, Italy.
authors.forename: Alessia
authors.initials: A
authors.lastname: Teruggi
authors.affiliation: Microbial Ecology Group, National Research Council - Institute of Ecosystem Study (CNR-ISE), Largo Tonolli 50, 28922, Verbania, Italy.
authors.forename: Diego
authors.initials: D
authors.lastname: Fontaneto
authors.affiliation: Microbial Ecology Group, National Research Council - Institute of Ecosystem Study (CNR-ISE), Largo Tonolli 50, 28922, Verbania, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Bertoni
authors.affiliation: Microbial Ecology Group, National Research Council - Institute of Ecosystem Study (CNR-ISE), Largo Tonolli 50, 28922, Verbania, Italy.
authors.forename: Cristiana
authors.initials: C
authors.lastname: Callieri
authors.affiliation: Microbial Ecology Group, National Research Council - Institute of Ecosystem Study (CNR-ISE), Largo Tonolli 50, 28922, Verbania, Italy.
authors.forename: Gianluca
authors.initials: G
authors.lastname: Corno
mesh_terms: D001419:Bacteria / Q000235:genetics*; D004269:DNA, Bacterial / Q000235:genetics; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D005798:Genes, Bacterial; D007558:Italy; D060106:Lakes / Q000382:microbiology*; D060888:Real-Time Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D013557:Switzerland
chemical_list: D004269:DNA, Bacterial
keywords: anthropic impact; antibiotic resistance genes; microbial ecology; quantitative real-time PCR; subalpine lakes