MAGs from Glacier-Fed Streams

The biofilm mode of life contributes to the success of microorganisms in extreme environments. Glacier-fed streams feature among Earth’s most extreme aquatic ecosystems because of marked oligotrophy and environmental fluctuations. Here, leveraging 156 metagenomes from the Vanishing Glaciers project, we report thousands of assembled genomes (MAGs) encompassing prokaryotes, algae, fungi, and viruses, and which are involved in biotic interactions within glacier-fed stream biofilms. Bacterial community composition varied regionally and was partially driven by environmental conditions. Bacterial MAGs were characterized by various strategies to exploit inorganic and organic energy sources, functional redundancy and mixotrophy, altogether possible adaptive responses to the glacier-fed stream environment. Our findings suggest that biofilms become more complex and switch from chemoautotrophy to heterotrophy as algal biomass increases in glacier-fed streams owing to glacier shrinkage. Our MAG compendium sheds light on the success of microbial life in glacier-fed streams and provides a resource for future research on a microbiome potentially imperiled by climate change.