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The hydrological context determines the beta-diversity of aerobic anoxygenic phototrophic bacteria in European Arctic seas but does not favor endemism.

Lehours AC, Jeanthon C - Front Microbiol (2015)

Bottom Line: A majority (>60%) of pufM sequences were affiliated to the Gammaproteobacteria reasserting that this class often represents the major component of the AAP bacterial community in oceanic regions.Two alphaproteobacterial groups dominate locally suggesting that they can constitute key players in this marine system transiently.Whereas we expected specific AAP bacterial populations in this peculiar and newly explored ecosystem, most pufM sequences were highly related to sequences retrieved elsewhere.

View Article: PubMed Central - PubMed

Affiliation: Laboratoire Microorganismes: Génome et Environnement, Clermont Université, Université Blaise Pascal Clermont-Ferrand, France ; Laboratoire Microorganismes: Génome et Environnement, Centre National de la Recherche Scientifique, UMR 6023 Aubière, France.

ABSTRACT
Despite an increasing number of studies over the last 15 years, aerobic anoxygenic photoheterotrophic (AAP) bacteria remain a puzzling functional group in terms of physiology, metabolism, and ecology. To contribute to a better knowledge of their environmental distribution, the present study aims at analyzing their diversity and structure at the boundary between the Norwegian, Greenland, and Barents Seas. The polymorphism of a marker gene encoding a sub-unit of the photosynthetic apparatus (pufM gene) was analyzed and attempted to be related to environmental parameters. The Atlantic or Arctic origin of water masses had a strong impact on the AAP bacterial community structure whose populations mostly belonged to the Alpha- and Gammaproteobacteria. A majority (>60%) of pufM sequences were affiliated to the Gammaproteobacteria reasserting that this class often represents the major component of the AAP bacterial community in oceanic regions. Two alphaproteobacterial groups dominate locally suggesting that they can constitute key players in this marine system transiently. We found that temperature is a major determinant of alpha diversity of AAP bacteria in this marine biome with specific clades emerging locally according to the partitioning of water masses. Whereas we expected specific AAP bacterial populations in this peculiar and newly explored ecosystem, most pufM sequences were highly related to sequences retrieved elsewhere. This observation highlights that the studied area does not favor AAP bacteria endemism but also opens new questions about the truthfulness of biogeographical patterns and on the extent of AAP bacterial diversity.

No MeSH data available.


Oceanographic context. (A) Map of the cruise area. The two transects S/N (south/north) and E/W (east/west) are indicated. Arrows represent surface circulation and origin of water masses (adapted from Not et al., 2005); (B) Principal component analysis of environmental parameters. The percentage of variability and the eigenvalue are indicated. Samples (circles) and variables (arrows) are plotted against the first two axes. Variables are salinity (psu), temperature (°C) and Chl a (μg L−1). The groups identified (G1, G2, and G3) were confirmed by ANOSIM statistics (data not shown). (C–E) Boxplots displaying (C) temperature, (D) salinity and Chl a concentration.
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Figure 1: Oceanographic context. (A) Map of the cruise area. The two transects S/N (south/north) and E/W (east/west) are indicated. Arrows represent surface circulation and origin of water masses (adapted from Not et al., 2005); (B) Principal component analysis of environmental parameters. The percentage of variability and the eigenvalue are indicated. Samples (circles) and variables (arrows) are plotted against the first two axes. Variables are salinity (psu), temperature (°C) and Chl a (μg L−1). The groups identified (G1, G2, and G3) were confirmed by ANOSIM statistics (data not shown). (C–E) Boxplots displaying (C) temperature, (D) salinity and Chl a concentration.

Mentions: Sampling was conducted in an area between the Norwegian, Greenland, and Barents Seas during an oceanographic cruise on board of the F/F Johan Hjort (Norwegian Institute of Marine Research) (Not et al., 2005). Ten stations were sampled from 20 August to 8 September 2002 along two transects (south/north, S/N and east/west, E/W) south of the Svalbard archipelago (Figure 1A). Samples were collected at several depths with a conductivity–temperature–depth (CTD) rosette system equipped with Niskin bottles (5 L). Nutrients were analyzed at the Norwegian Institute of Marine Research using standard techniques, and chlorophyll a (Chl a) concentrations were determined on board. An overview of position, bottom depth and hydrology for each sampling station was previously reported (Not et al., 2005). At all stations, water samples for DNA analysis were collected as described by Lovejoy et al. (2006). Briefly, water was prefiltered to remove large organisms and particles and microbial biomass was collected in 0.22 μm Sterivex filter units with a peristaltic pumping system. Filters were frozen at −80°C in lysis buffer (40 mM EDTA, 50 mM Tris-HCl, 0.75 M sucrose) until nucleic acids were extracted.


The hydrological context determines the beta-diversity of aerobic anoxygenic phototrophic bacteria in European Arctic seas but does not favor endemism.

Lehours AC, Jeanthon C - Front Microbiol (2015)

Oceanographic context. (A) Map of the cruise area. The two transects S/N (south/north) and E/W (east/west) are indicated. Arrows represent surface circulation and origin of water masses (adapted from Not et al., 2005); (B) Principal component analysis of environmental parameters. The percentage of variability and the eigenvalue are indicated. Samples (circles) and variables (arrows) are plotted against the first two axes. Variables are salinity (psu), temperature (°C) and Chl a (μg L−1). The groups identified (G1, G2, and G3) were confirmed by ANOSIM statistics (data not shown). (C–E) Boxplots displaying (C) temperature, (D) salinity and Chl a concentration.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4490794&req=5

Figure 1: Oceanographic context. (A) Map of the cruise area. The two transects S/N (south/north) and E/W (east/west) are indicated. Arrows represent surface circulation and origin of water masses (adapted from Not et al., 2005); (B) Principal component analysis of environmental parameters. The percentage of variability and the eigenvalue are indicated. Samples (circles) and variables (arrows) are plotted against the first two axes. Variables are salinity (psu), temperature (°C) and Chl a (μg L−1). The groups identified (G1, G2, and G3) were confirmed by ANOSIM statistics (data not shown). (C–E) Boxplots displaying (C) temperature, (D) salinity and Chl a concentration.
Mentions: Sampling was conducted in an area between the Norwegian, Greenland, and Barents Seas during an oceanographic cruise on board of the F/F Johan Hjort (Norwegian Institute of Marine Research) (Not et al., 2005). Ten stations were sampled from 20 August to 8 September 2002 along two transects (south/north, S/N and east/west, E/W) south of the Svalbard archipelago (Figure 1A). Samples were collected at several depths with a conductivity–temperature–depth (CTD) rosette system equipped with Niskin bottles (5 L). Nutrients were analyzed at the Norwegian Institute of Marine Research using standard techniques, and chlorophyll a (Chl a) concentrations were determined on board. An overview of position, bottom depth and hydrology for each sampling station was previously reported (Not et al., 2005). At all stations, water samples for DNA analysis were collected as described by Lovejoy et al. (2006). Briefly, water was prefiltered to remove large organisms and particles and microbial biomass was collected in 0.22 μm Sterivex filter units with a peristaltic pumping system. Filters were frozen at −80°C in lysis buffer (40 mM EDTA, 50 mM Tris-HCl, 0.75 M sucrose) until nucleic acids were extracted.

Bottom Line: A majority (>60%) of pufM sequences were affiliated to the Gammaproteobacteria reasserting that this class often represents the major component of the AAP bacterial community in oceanic regions.Two alphaproteobacterial groups dominate locally suggesting that they can constitute key players in this marine system transiently.Whereas we expected specific AAP bacterial populations in this peculiar and newly explored ecosystem, most pufM sequences were highly related to sequences retrieved elsewhere.

View Article: PubMed Central - PubMed

Affiliation: Laboratoire Microorganismes: Génome et Environnement, Clermont Université, Université Blaise Pascal Clermont-Ferrand, France ; Laboratoire Microorganismes: Génome et Environnement, Centre National de la Recherche Scientifique, UMR 6023 Aubière, France.

ABSTRACT
Despite an increasing number of studies over the last 15 years, aerobic anoxygenic photoheterotrophic (AAP) bacteria remain a puzzling functional group in terms of physiology, metabolism, and ecology. To contribute to a better knowledge of their environmental distribution, the present study aims at analyzing their diversity and structure at the boundary between the Norwegian, Greenland, and Barents Seas. The polymorphism of a marker gene encoding a sub-unit of the photosynthetic apparatus (pufM gene) was analyzed and attempted to be related to environmental parameters. The Atlantic or Arctic origin of water masses had a strong impact on the AAP bacterial community structure whose populations mostly belonged to the Alpha- and Gammaproteobacteria. A majority (>60%) of pufM sequences were affiliated to the Gammaproteobacteria reasserting that this class often represents the major component of the AAP bacterial community in oceanic regions. Two alphaproteobacterial groups dominate locally suggesting that they can constitute key players in this marine system transiently. We found that temperature is a major determinant of alpha diversity of AAP bacteria in this marine biome with specific clades emerging locally according to the partitioning of water masses. Whereas we expected specific AAP bacterial populations in this peculiar and newly explored ecosystem, most pufM sequences were highly related to sequences retrieved elsewhere. This observation highlights that the studied area does not favor AAP bacteria endemism but also opens new questions about the truthfulness of biogeographical patterns and on the extent of AAP bacterial diversity.

No MeSH data available.