Infrequent Transitions between Saline and Fresh Waters in One of the Most Abundant Microbial Lineages (SAR11)

Logares, Ramiro; Bråte, Jon; Heinrich, Friederike; Shalchian-Tabrizi, Kamran; Bertilsson, Stefan

doi:10.1093/molbev/msp239

Cited by 76 publications

(96 citation statements)

References 40 publications

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“…Although ancient, colonization of freshwater sediment occurred more recently than for saline sediments in a first transition and subsequent diversification events that gave rise to all freshwater MCG-IL (Figure 6). Overall, and in agreement with other microbial lineages (Logares et al, 2009(Logares et al, , 2010), a few environmental transition events (that is, switch from a freshwater ancestor to a saline descendant and vice versa) seemed to have occurred during the diversification of MCG. This result may explain why freshwater and saline sediments harbored evolutionary distinct communities of MCG.…”

Section: Evolutionary Relationships Between Freshwater and Marine Mcgsupporting

confidence: 85%

Insights in the ecology and evolutionary history of the Miscellaneous Crenarchaeotic Group lineage

et al. 2015

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Members of the archaeal Miscellaneous Crenarchaeotic Group (MCG) are among the most successful microorganisms on the planet. During its evolutionary diversification, this very diverse group has managed to cross the saline-freshwater boundary, one of the most important evolutionary barriers structuring microbial communities. However, the current understanding on the ecological significance of MCG in freshwater habitats is scarce and the evolutionary relationships between freshwater and saline MCG remains poorly known. Here, we carried out molecular phylogenies using publicly available 16S rRNA gene sequences from various geographic locations to investigate the distribution of MCG in freshwater and saline sediments and to evaluate the implications of salinefreshwater transitions during the diversification events. Our approach provided a robust ecological framework in which MCG archaea appeared as a core generalist group in the sediment realm. However, the analysis of the complex intragroup phylogeny of the 21 subgroups currently forming the MCG lineage revealed that distinct evolutionary MCG subgroups have arisen in marine and freshwater sediments suggesting the occurrence of adaptive evolution specific to each habitat. The ancestral state reconstruction analysis indicated that this segregation was mainly due to the occurrence of a few saline-freshwater transition events during the MCG diversification. In addition, a network analysis showed that both saline and freshwater MCG recurrently co-occur with archaea of the class Thermoplasmata in sediment ecosystems, suggesting a potentially relevant trophic connection between the two clades.

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Section: Evolutionary Relationships Between Freshwater and Marine Mcgsupporting

confidence: 85%

Insights in the ecology and evolutionary history of the Miscellaneous Crenarchaeotic Group lineage

et al. 2015

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“…hyp -oxia) or a more recent ecological diversification of LD12 that is not detected in the rather slowly evolving 16S rRNA gene. Previous phylogenetic analyses of LD12 from a global 16S rRNA database do support microdiversification and hence the existence of ecologically and genetically diversified LD12 populations (Logares et al 2010). A more recent phylogeographic analysis suggests that such subclusters (supported bootstrap values > 50%) were typically restricted to single lakes, but several clusters could occasionally also be detected within a single system (Lake Zürich; Salcher et al 2011a).…”

Section: Discussionmentioning

confidence: 95%

Seasonality and environmental control of freshwater SAR11 (LD12) in a temperate lake (Lake Erken, Sweden)

Heinrich¹,

Eiler²,

Bertilsson³

2013

Aquat. Microb. Ecol.

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THE SAR11 clade is ubiquitous and abundant in planktonic environments. In freshwater lakes, the clade is represented by tribe LD12 which is phylogenetically distinct from the marine SAR11. We studied the ecology of LD12 in a temperate dimictic lake (Lake Erken, Sweden), by analyzing its seasonal dynamics with quantitative PCR, CARD-FISH and 454 pyrosequencing of the 16S rRNA gene. Results showed that LD12 can be as numerous in freshwater bacterioplankton as their marine SAR11 siblings. They exhibited strong seasonality and made up from 1.8 to 40% of the total bacterial 16S rRNA pool (mean 14%) with pronounced peaks in summer and late fall. Except in spring, LD12 was the dominant Alphaproteobacteria, contributing on average 72% of the 16S rRNA within this class. The LD12 population was dominated by a single persistent ribotype, suggesting low local divergence, at least at the phylogenetic resolution accessed with rRNA genes. The relative abundance of LD12 was positively correlated to nutrient concentrations (phosphate, ammonia, nitrate, and silica) and water transparency whereas the relative abundance was lower during periods characterized by high phytoplankton biomass. Based on these observations we propose that LD12 are poor competitors during periods of high phytoplankton productivity and associated release of labile organic compounds, but thrive when availability of inorganic nutrients is high. Similar to the marine SAR11 sibling group, local LD12 populations appear to respond in contrasting ways to nutrient availability in different lakes, pointing to either ecological divergence within the tribe or variations in the interplay between environmental driver variables.

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“…(Logares et al 2010). SAR11 bacteria are often a numerically dominant component of prokaryotic communities in marine waters (Morris et al 2002), and there is one lineage of SAR11 that is found mainly in brackish waters (Logares et al 2010).…”

Section: Discussionmentioning

confidence: 99%

“…Marine organisms are isotonic or hypotonic, while freshwater ones are hypertonic. Both physiology and the cost of osmoregulation make the marine-freshwater boundary an insurmountable barrier for many bacteria (Logares et al 2010). As a result, there is almost no overlap in the community composition of marine and freshwater species.…”

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confidence: 99%

Seasonal dynamics and activity of typical freshwater bacteria in brackish waters of the Gulf of Gdańsk

Piwosz

Salcher

Zeder

et al. 2013

Limnology & Oceanography

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While typical freshwater and marine bacteria have been found to co-occur in brackish habitats, it is unknown if they are active members of the local bacterial assemblages or if their presence is the result of passive transport only. We followed the seasonal dynamics of typical freshwater bacteria (R-BT lineage of Betaproteobacteria; Ac1 Actinobacteria; LD12 Alphaproteobacteria) and of marine SAR11 Alphaproteobacteria in the brackish water of the Gulf of Gdań sk (southern Baltic Sea), and we assessed their incorporation of thymidine and leucine at three distinct environmental conditions. The temporal development of bacteria was driven not only by local conditions but also by phenomena resulting from the dynamic hydrology of the site. Both temperature and salinity were important factors influencing bacterial community composition, as reflected by the clear distinction of three assemblages in spring and summer and during a period of enhanced freshwater influx. During spring, high proportions of R-BT Betaproteobacteria and Ac1 Actinobacteria incorporated the radiolabeled tracers, and all three freshwater lineages were most active during the subsequent phase of low salinity. The summer period was characterized by highest abundances of Ac1 Actinobacteria and of both alphaproteobacterial lineages. All studied freshwater lineages were active members of the brackish water communities at specific environmental conditions, including LD12 Alphaproteobacteria, which have so far been considered to thrive exclusively in freshwater habitats. By contrast, the presence of the typical marine SAR11 bacteria seemed to result from passive inflow with more saline waters from the Baltic proper.Marine and freshwater systems pose very distinct challenges for aquatic organisms. While offshore pelagic waters are often oligotrophic and with limited terrestrial effect, lakes and rivers are comparatively small, discontinuous habitats with productivity ranging from oligotropic to eutrophic and often featuring high input of terrestrial organic matter from the catchment. However, the most conspicuous difference is salinity. Marine organisms are isotonic or hypotonic, while freshwater ones are hypertonic. Both physiology and the cost of osmoregulation make the marine-freshwater boundary an insurmountable barrier for many bacteria (Logares et al.

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Infrequent Transitions between Saline and Fresh Waters in One of the Most Abundant Microbial Lineages (SAR11)

Cited by 76 publications

References 40 publications

Insights in the ecology and evolutionary history of the Miscellaneous Crenarchaeotic Group lineage

Insights in the ecology and evolutionary history of the Miscellaneous Crenarchaeotic Group lineage

Seasonality and environmental control of freshwater SAR11 (LD12) in a temperate lake (Lake Erken, Sweden)

Seasonal dynamics and activity of typical freshwater bacteria in brackish waters of the Gulf of Gdańsk

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