title: Summer Abundance and Distribution of Proteorhodopsin Genes in the Western Arctic Ocean.
abstract: Proteorhodopsins (PR) are phylogenetically diverse and highly expressed proton pumps in marine bacterial communities. The phylogenetic diversity andin situexpression of the main PR groups in polar off-shore, 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 toGammaproteobacteria, Alphaproteobacteria, andBacteroidetes. Substantial overlap (78%) between DNA- and cDNA-based librairies indicatedin situPR 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,Alphaproteobacteriapredominated 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.
authors: CNRS, Station Biologique, UMR 7144 Adaptation and Diversité en Milieu MarinRoscoff, France; Sorbonne Universités - UPMC Université Paris 06, Station Biologique, UMR 7144 Adaptation and Diversité en Milieu MarinRoscoff, France.
authors: Dominique
authors: D
authors: Boeuf
authors: CNRS, USR 3579, Laboratoire de Biodiversité et Biotechnologies MicrobiennesBanyuls-sur-Mer, France; Sorbonne Universités - UPMC Université Paris 06, USR 3579, Observatoire OcéanologiqueBanyuls-sur-Mer, France.
authors: Raphaël
authors: R
authors: Lami
authors: CNRS, Station Biologique, UMR 7144 Adaptation and Diversité en Milieu MarinRoscoff, France; Sorbonne Universités - UPMC Université Paris 06, Station Biologique, UMR 7144 Adaptation and Diversité en Milieu MarinRoscoff, France.
authors: Emelyne
authors: E
authors: Cunnington
authors: CNRS, Station Biologique, UMR 7144 Adaptation and Diversité en Milieu MarinRoscoff, France; Sorbonne Universités - UPMC Université Paris 06, Station Biologique, UMR 7144 Adaptation and Diversité en Milieu MarinRoscoff, France.
authors: Christian
authors: C
authors: Jeanthon
keywords: Arctic Ocean; Mackenzie River; SAR11; photoheterotrophy; proteorhodopsin