Benthic Biofilms in Glacier-Fed Streams from Scandinavia to the Himalayas Host Distinct Bacterial Communities Compared with the Streamwater
Leïla Ezzat, Stilianos Fodelianakis, Tyler J. Kohler, Massimo Bourquin, Jade Brandani, Susheel Bhanu Busi, Daniele Daffonchio, Vincent De Staercke, Ramona Marasco, Grégoire Michoud, Emmy Oppliger, Hannes Peter, Paraskevi Pramateftaki, Martina Schön, Michael Styllas, Virginia Tadei, Matteo Tolosano, Tom J. Battin
Abstract
Benthic biofilms represent the dominant form of life in glacier-fed streams. However, it remains unclear how bacterial communities within these biofilms assemble. Our findings from glacier-fed streams from three major mountain ranges across the Himalayas, the European Alps and the Scandinavian Mountains reveal a bacterial community associated with benthic biofilms that is distinct from the assemblage in the overlying streamwater. Our analyses suggest that selection is the underlying process to this differentiation. This is unexpected given that bacterial cells that are freely living or attached to the abundant sediment particles suspended in the water continuously mix with the benthic biofilms. The latter colonize loose sediments that are subject to high turnover owing to the forces of the water flow. Our research unravels the existence of a microbiome specific to benthic biofilms in glacier-fed streams, now under major threats due to global warming.