Changes in sediment microbial diversity following chronic copper-exposure induce community copper-tolerance without increasing sensitivity to arsenic

• Published in: Journal of hazardous materials Vol. 391; p. 122197
• Main Authors: Mahamoud Ahmed, Ayanleh, Tardy, Vincent, Bonnineau, Chloé, Billard, Patrick, Pesce, Stéphane, Lyautey, Emilie
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 05-06-2020; Elsevier
• Subjects: Archaea - drug effects; Archaea - genetics; Arsenic - toxicity; Bacteria - drug effects; Bacteria - genetics; Co-tolerance; Copper - toxicity; Environmental Sciences; Geologic Sediments - microbiology; High-throughput sequencing; Microbial ecotoxicology; Microbiota - drug effects; PICT; Resistance genes; Soil Pollutants - toxicity; Co-tolerance; Microbial ecotoxicology; High-throughput sequencing; Resistance genes; PICT
• ISSN: 0304-3894; 1873-3336; 1873-3336
• DOI: 10.1016/j.jhazmat.2020.122197

[Display omitted]
•Sediment exposure to environmental Cu concentrations decreases microbial diversity.•Large changes in community composition occurred, with fifty genera affected by Cu.•Absolute abundance of the Cu resistance gene did not increase, but tolerance did.•Cu-induced changes generated diversity and functional costs at the community level.•Costs of Cu adaptation did not increase community sensitivity to As toxicity.
Sediment microbial communities were exposed for 21 days to an environmental concentration of copper to assess Cu-induced composition changes and resulting effects on microbial sensitivity to acute Cu and As toxicity. Chronic Cu exposure reduced the diversity of the bacterial and archaeal communities from Day 0 to Day 21. The pollution-induced community tolerance concept (PICT) predicts that loss of the most sensitive taxa and gain of more tolerant ones should increase the capacity of Cu-exposed communities to tolerate acute Cu toxicity. Although diversity loss and functional costs of adaptation could have increased their sensitivity to subsequent toxic stress, no increased sensitivity to As was observed. PICT responses varied according to heterotrophic activity, selected as the functional endpoint for toxicity testing, with different results for Cu and As. This suggests that induced tolerance to Cu and As was supported by different species with different metabolic capacities. Ecological risk assessment of contaminants would gain accuracy from further research on the relative contribution of tolerance acquisition and co-tolerance processes on the functional response of microbial communities.