Summer Abundance and Distribution of Proteorhodopsin Genes in the Western Arctic Ocean

• Published in: Frontiers in Microbiology
• Main Authors: Boeuf, Dominique, Lami, Raphaël, Cunnington, Emelyne, Jeanthon, Christian
• Other Authors: Adaptation et diversité en milieu marin (AD2M), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Station biologique de Roscoff (SBR), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Biodiversité et Biotechnologies Microbiennes (LBBM), PIERRE FABRE-EDF (EDF)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Observatoire océanologique de Banyuls (OOB), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2016
• Subjects: Mackenzie River; SAR11; photoheterotrophy; proteorhodopsin; Arctic Ocean; [SDE]Environmental Sciences; [SDE.BE]Environmental Sciences/Biodiversity and Ecology; Arctic; Beaufort Sea; Mackenzie river; Mackenzie Shelf
• Online Access: https://hal.archives-ouvertes.fr/hal-02130561; https://hal.archives-ouvertes.fr/hal-02130561/document; https://hal.archives-ouvertes.fr/hal-02130561/file/Boeuf%20et%20al.%202016.%20PR%20in%20the%20arctic%20ocean.pdf; https://doi.org/10.3389/fmicb.2016.01584

International audience Proteorhodopsins (PR) are phylogenetically diverse and highly expressed proton pumps in marine bacterial communities. The phylogenetic diversity and in situ expression of the main PR groups in polar offshore , coastal and estuarine waters is poorly known and their abundance has not yet been reported. Here, we show that PR gene sequences of the southern Beaufort Sea including MacKenzie shelf and estuary are mainly affiliated to Gammaproteobacteria, Alphaproteobacteria, and Bacteroidetes. Substantial overlap (78%) between DNA-and cDNA-based librairies indicated in situ PR transcription within a large fraction of PR-containing community. Sets of specific qPCR primers were designed to measure the absolute abundances of the major PR types. Spatial and depth profiles showed that PR-containing bacteria were abundant throughout the photic zone, comprising up to 45% of total bacteria. Although their abundance varied greatly with location and depth, Alphaproteobacteria predominated in the PR community in all water masses, with SAR11 as the major PR type. Low nutrient concentrations rather than light were the environmental drivers that best explained the abundance and distribution of arctic PR types. Together, our data suggests that PR-based phototrophy could be the major phototrophic prokaryotic process during the Arctic Ocean summer.