Limits...
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.


Relationship between relative abundance of OTUs and environmental parameters. (A) Canonical correspondence analysis performed using relative abundance of OTUs. OTUs (squares), stations (circles), and variables (arrows) are plotted against the first two axes. Samples are labeled as follows: Station-depth. Colors used to represent stations are identical to those in the Figure 3. OTUs are colored according to their phylogroup affiliation (see Figure 3). The blue and red ellipses illustrated the temperature and salinity/trophic gradient, respectively. Plots of the correlation between the relative abundance of SPIT19, SPIT29, and SPIT31 (B) and of SPIT3, SPIT7, and SPIT10 (C) with temperature. All the correlations are significant (p < 0.05).
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4490794&req=5

Figure 4: Relationship between relative abundance of OTUs and environmental parameters. (A) Canonical correspondence analysis performed using relative abundance of OTUs. OTUs (squares), stations (circles), and variables (arrows) are plotted against the first two axes. Samples are labeled as follows: Station-depth. Colors used to represent stations are identical to those in the Figure 3. OTUs are colored according to their phylogroup affiliation (see Figure 3). The blue and red ellipses illustrated the temperature and salinity/trophic gradient, respectively. Plots of the correlation between the relative abundance of SPIT19, SPIT29, and SPIT31 (B) and of SPIT3, SPIT7, and SPIT10 (C) with temperature. All the correlations are significant (p < 0.05).

Mentions: A canonical correspondence analysis (CCA) was performed using relative proportions of OTUs to determine if specific AAP bacterial populations are associated with specific environmental parameters. Consistent with the clustering deduced from TTGE analyses the sampled stations grouped in the CCA according to Atlantic or Arctic water masses (Figure 4A) reinforcing the notion that the structure of AAP populations at a fine phylogenetic scale is closely related to the partitioning of water masses. This beta-diversity pattern of AAP bacteria is supported by observation of AAP populations exhibiting a clear preference for some hydrological features, notably temperature preferences (Figures 4A–C). For example, SPIT19, SPIT29, and SPIT31 seem to thrive in warmer waters (Figure 4B). Positive or negative significant correlations (p < 0.05) were also found between Chla concentrations and the relative abundance of SPIT1 (r = 0.62), SPIT28 (r = 0.71), SPIT29 (r = −0.6), but also between salinity and the relative abundance of SPIT19 (r = −0.91), SPIT21 (r = −0.65) and SPIT31 (r = −0.65). However, understanding the factors that govern the environmental distribution AAP bacteria is not so simple, as illustrated by the relationship between the relative abundances of OTUs SPIT3, SPIT7, and SPIT10 and temperature (Figure 4C). The significant (p < 0.05) negative correlation observed suggests that the corresponding AAP populations are favored by colder waters (Figure 4B). However, their increased occurrence at temperatures >12°C (Figure 4C) and their phylogenetic affiliation with pufM sequences retrieved from warmer biomes (Figure 3A, Table S2) illustrated that AAP populations probably exhibit an ecotypic differentiation as postulated previously (Waidner and Kirchman, 2008; Lehours et al., 2010).


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)

Relationship between relative abundance of OTUs and environmental parameters. (A) Canonical correspondence analysis performed using relative abundance of OTUs. OTUs (squares), stations (circles), and variables (arrows) are plotted against the first two axes. Samples are labeled as follows: Station-depth. Colors used to represent stations are identical to those in the Figure 3. OTUs are colored according to their phylogroup affiliation (see Figure 3). The blue and red ellipses illustrated the temperature and salinity/trophic gradient, respectively. Plots of the correlation between the relative abundance of SPIT19, SPIT29, and SPIT31 (B) and of SPIT3, SPIT7, and SPIT10 (C) with temperature. All the correlations are significant (p < 0.05).
© Copyright Policy
Related In: Results  -  Collection

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

Figure 4: Relationship between relative abundance of OTUs and environmental parameters. (A) Canonical correspondence analysis performed using relative abundance of OTUs. OTUs (squares), stations (circles), and variables (arrows) are plotted against the first two axes. Samples are labeled as follows: Station-depth. Colors used to represent stations are identical to those in the Figure 3. OTUs are colored according to their phylogroup affiliation (see Figure 3). The blue and red ellipses illustrated the temperature and salinity/trophic gradient, respectively. Plots of the correlation between the relative abundance of SPIT19, SPIT29, and SPIT31 (B) and of SPIT3, SPIT7, and SPIT10 (C) with temperature. All the correlations are significant (p < 0.05).
Mentions: A canonical correspondence analysis (CCA) was performed using relative proportions of OTUs to determine if specific AAP bacterial populations are associated with specific environmental parameters. Consistent with the clustering deduced from TTGE analyses the sampled stations grouped in the CCA according to Atlantic or Arctic water masses (Figure 4A) reinforcing the notion that the structure of AAP populations at a fine phylogenetic scale is closely related to the partitioning of water masses. This beta-diversity pattern of AAP bacteria is supported by observation of AAP populations exhibiting a clear preference for some hydrological features, notably temperature preferences (Figures 4A–C). For example, SPIT19, SPIT29, and SPIT31 seem to thrive in warmer waters (Figure 4B). Positive or negative significant correlations (p < 0.05) were also found between Chla concentrations and the relative abundance of SPIT1 (r = 0.62), SPIT28 (r = 0.71), SPIT29 (r = −0.6), but also between salinity and the relative abundance of SPIT19 (r = −0.91), SPIT21 (r = −0.65) and SPIT31 (r = −0.65). However, understanding the factors that govern the environmental distribution AAP bacteria is not so simple, as illustrated by the relationship between the relative abundances of OTUs SPIT3, SPIT7, and SPIT10 and temperature (Figure 4C). The significant (p < 0.05) negative correlation observed suggests that the corresponding AAP populations are favored by colder waters (Figure 4B). However, their increased occurrence at temperatures >12°C (Figure 4C) and their phylogenetic affiliation with pufM sequences retrieved from warmer biomes (Figure 3A, Table S2) illustrated that AAP populations probably exhibit an ecotypic differentiation as postulated previously (Waidner and Kirchman, 2008; Lehours et al., 2010).

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.