Redox potential, not phototrophy, drives functional stratification amongst novel organisms in boreal lakes

1 Desembre 2017
Sala d'Actes
Impartida per: 
Dr. Sari Peura
Swedish University of Agricultural Sciences, Uppsala, Sweden


Autotrophic processes sustain all ecosystems. The main energy source for this process is sun light, and major biomes like surface oceans and boreal forests are net autotrophic. Thus, total carbon fixation within the ecosystem exceeds respiration, making them net carbon sinks. However, certain habitats, such as boreal lakes, are light limited and hypothesized to be net heterotrophic. Here we show that autotrophy through phototrophic and lithotrophic pathways facilitates carbon fixation in a boreal lake even below the euphotic zone. A vertical transect of the lake revealed multiple chemolithoautotrophic organisms belonging to novel or poorly characterized phyla deriving their energy from reactions related to sulfur, iron and nitrogen transformations. Lithoautotrophic pathways were highly abundant through the water column and the chemical stratification was linked to energy pathways predicted from metagenome assembled genomes. This suggests that photoautotrophic pathways may not be the sole or dominant autotrophic pathway prevalent in boreal lakes as currently thought. Further, the high autotrophic potential in the lake metagenome below euphotic zone suggests the need for revising our concepts of internal carbon cycling in boreal lakes.


Brief biography

Dr. Peura is an Associate Senior Lecturer and a SciLifeLab Fellow in the Department of Forest Mycology and Plant Pathology at Swedish University of Agricultural Sciences (Sweden). Her research interests include aquatic microbial ecology and biogeochemical cycles in combination with climate change. To study these Dr. Peura is combining molecular methods with environmental data for a comprehensive understanding of the interactions between microbes and their environment. Dr. Peura did her graduate work at the University of Jyväskylä (Finland) and finished her PhD in 2012. In 2013, after a postdoc period at the University of Michigan (USA), she got funding from the Academy of Finland to start her own research at the Uppsala University. She started at her current position 2017 and her research is funded by Science for Life Laboratories and Swedish research agency FORMAS.