Geochemical and metagenomics study of a metal-rich, green-turquoise-coloured stream in the southern Swiss Alps

• Published in: PloS one Vol. 16; no. 3; p. e0248877
• Main Authors: Buetti-Dinh, Antoine, Ruinelli, Michela, Czerski, Dorota, Scapozza, Cristian, Martignier, Agathe, Roman, Samuele, Caminada, Annapaola, Tonolla, Mauro
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 30.03.2021; Public Library of Science (PLoS)
• Subjects: Acidification; Adaptation; Aquifers; Bacterial leaching; Biofilms; Biology; Biology and Life Sciences; Bioremediation; Botany; Chemical composition; Cyanobacteria; Deoxyribonucleic acid; Design; DNA; Earth science; Earth Sciences; Environments; Extreme environments; Genetic aspects; Genotype; Heavy metals; Identification and classification; Inductively coupled plasma mass spectrometry; Laboratories; Mass spectrometry; Mass spectroscopy; Medicine and Health Sciences; Metagenomics; Metal ions; Microbial activity; Microbial mats; Microbiological research; Microbiology; Microorganisms; Microscopy; Oxidative stress; Photosynthesis; Physical Sciences; Polypropylene; Research and Analysis Methods; Scientific imaging; Spring water; Sulfur; Water analysis; Water sampling; Water springs; Switzerland
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0248877

The Swiss Alpine environments are poorly described from a microbiological perspective. Near the Greina plateau in the Camadra valley in Ticino (southern Swiss Alps), a green-turquoise-coloured water spring streams off the mountain cliffs. Geochemical profiling revealed naturally elevated concentrations of heavy metals such as copper, lithium, zinc and cadmium, which are highly unusual for the geomorphology of the region. Of particular interest, was the presence of a thick biofilm, that was revealed by microscopic analysis to be mainly composed of Cyanobacteria. A metagenome was further assembled to detail the genes found in this environment. A multitude of genes for resistance/tolerance to high heavy metal concentrations were indeed found, such as, various transport systems, and genes involved in the synthesis of extracellular polymeric substances (EPS). EPS have been evoked as a central component in photosynthetic environments rich in heavy metals, for their ability to drive the sequestration of toxic, positively-charged metal ions under high regimes of cyanobacteria-driven photosynthesis. The results of this study provide a geochemical and microbiological description of this unusual environment in the southern Swiss Alps, the role of cyanobacterial photosynthesis in metal resistance, and the potential role of such microbial community in bioremediation of metal-contaminated environments.