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Particle-Associated Differ from Free-Living Bacteria in Surface Waters of the Baltic Sea.

Rieck A, Herlemann DP, Jürgens K, Grossart HP - Front Microbiol (2015)

Bottom Line: Although temporal and spatial gradients in environmental variables are known to shape BCC, it remains unclear how and to what extent PA and FL bacterial diversity responds to such environmental changes.To elucidate the BCC of both bacterial fractions related to different environmental settings, we studied surface samples of three Baltic Sea stations (marine, mesohaline, and oligohaline) in two different seasons (summer and fall/winter).In general, a high fraction of bacterial OTUs was found exclusively in the PA fraction (52% of total OTUs).

View Article: PubMed Central - PubMed

Affiliation: Leibniz-Institute of Freshwater Ecology and Inland Fisheries Stechlin, Germany.

ABSTRACT
Many studies on bacterial community composition (BCC) do not distinguish between particle-associated (PA) and free-living (FL) bacteria or neglect the PA fraction by pre-filtration removing most particles. Although temporal and spatial gradients in environmental variables are known to shape BCC, it remains unclear how and to what extent PA and FL bacterial diversity responds to such environmental changes. To elucidate the BCC of both bacterial fractions related to different environmental settings, we studied surface samples of three Baltic Sea stations (marine, mesohaline, and oligohaline) in two different seasons (summer and fall/winter). Amplicon sequencing of the 16 S rRNA gene revealed significant differences in BCC of both bacterial fractions among stations and seasons, with a particularly high number of PA operational taxonomic units (OTUs at genus-level) at the marine station in both seasons. "Shannon and Simpson indices" showed a higher diversity of PA than FL bacteria at the marine station in both seasons and at the oligohaline station in fall/winter. In general, a high fraction of bacterial OTUs was found exclusively in the PA fraction (52% of total OTUs). These findings indicate that PA bacteria significantly contribute to overall bacterial richness and that they differ from FL bacteria. Therefore, to gain a deeper understanding on diversity and dynamics of aquatic bacteria, PA and FL bacteria should be generally studied independently.

No MeSH data available.


Study area (Baltic Sea) and station locations. Dots represent sampling stations considered as “marine” (mar), “mesohaline” (meso) and “oligohaline” (oligo) station.
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Figure 1: Study area (Baltic Sea) and station locations. Dots represent sampling stations considered as “marine” (mar), “mesohaline” (meso) and “oligohaline” (oligo) station.

Mentions: The sampling was performed in the scope of the ATKiM (“Abbaubarkeit von arktischem, terrigenem Kohlenstoff im Meer”) project during two cruises (M86-1, M87-3) of the RV Meteor in the Baltic Sea: (i) November/December 2011 (“fall/winter”) and (ii) May/June 2012 (“summer”). Sampling locations (Figure 1) were characterized by differences in salinity and defined as marine (Skagerrak, salinity ≈ 30-34; N 58°07′59.88′′, E010°0′0′′), mesohaline (Gotland Basin, salinity ~ 7; N57°18′20.52′′; E020°04′41.5′′) and oligohaline (Bothnian Bay, salinity ≈2.7; N65°26′42′′, E023°17′53.88′′). Surface water of the three different sampling stations was collected with a 400 dm3 stainless steel water sampler (Hydrobios, Kiel, Germany) from which triplicate samples were taken (representing “technical replicates”). The samples were pre-filtrated through a 100 μm mesh filter to exclude large zooplankton and then directly transferred into 25 L polyethylene canisters from which subsamples were taken at 10°C for further analyses. The bacteria collected on the 5-μm filter were considered to represent the PA fraction and the bacteria collected on the 0.2−μm filters the FL fraction.


Particle-Associated Differ from Free-Living Bacteria in Surface Waters of the Baltic Sea.

Rieck A, Herlemann DP, Jürgens K, Grossart HP - Front Microbiol (2015)

Study area (Baltic Sea) and station locations. Dots represent sampling stations considered as “marine” (mar), “mesohaline” (meso) and “oligohaline” (oligo) station.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4664634&req=5

Figure 1: Study area (Baltic Sea) and station locations. Dots represent sampling stations considered as “marine” (mar), “mesohaline” (meso) and “oligohaline” (oligo) station.
Mentions: The sampling was performed in the scope of the ATKiM (“Abbaubarkeit von arktischem, terrigenem Kohlenstoff im Meer”) project during two cruises (M86-1, M87-3) of the RV Meteor in the Baltic Sea: (i) November/December 2011 (“fall/winter”) and (ii) May/June 2012 (“summer”). Sampling locations (Figure 1) were characterized by differences in salinity and defined as marine (Skagerrak, salinity ≈ 30-34; N 58°07′59.88′′, E010°0′0′′), mesohaline (Gotland Basin, salinity ~ 7; N57°18′20.52′′; E020°04′41.5′′) and oligohaline (Bothnian Bay, salinity ≈2.7; N65°26′42′′, E023°17′53.88′′). Surface water of the three different sampling stations was collected with a 400 dm3 stainless steel water sampler (Hydrobios, Kiel, Germany) from which triplicate samples were taken (representing “technical replicates”). The samples were pre-filtrated through a 100 μm mesh filter to exclude large zooplankton and then directly transferred into 25 L polyethylene canisters from which subsamples were taken at 10°C for further analyses. The bacteria collected on the 5-μm filter were considered to represent the PA fraction and the bacteria collected on the 0.2−μm filters the FL fraction.

Bottom Line: Although temporal and spatial gradients in environmental variables are known to shape BCC, it remains unclear how and to what extent PA and FL bacterial diversity responds to such environmental changes.To elucidate the BCC of both bacterial fractions related to different environmental settings, we studied surface samples of three Baltic Sea stations (marine, mesohaline, and oligohaline) in two different seasons (summer and fall/winter).In general, a high fraction of bacterial OTUs was found exclusively in the PA fraction (52% of total OTUs).

View Article: PubMed Central - PubMed

Affiliation: Leibniz-Institute of Freshwater Ecology and Inland Fisheries Stechlin, Germany.

ABSTRACT
Many studies on bacterial community composition (BCC) do not distinguish between particle-associated (PA) and free-living (FL) bacteria or neglect the PA fraction by pre-filtration removing most particles. Although temporal and spatial gradients in environmental variables are known to shape BCC, it remains unclear how and to what extent PA and FL bacterial diversity responds to such environmental changes. To elucidate the BCC of both bacterial fractions related to different environmental settings, we studied surface samples of three Baltic Sea stations (marine, mesohaline, and oligohaline) in two different seasons (summer and fall/winter). Amplicon sequencing of the 16 S rRNA gene revealed significant differences in BCC of both bacterial fractions among stations and seasons, with a particularly high number of PA operational taxonomic units (OTUs at genus-level) at the marine station in both seasons. "Shannon and Simpson indices" showed a higher diversity of PA than FL bacteria at the marine station in both seasons and at the oligohaline station in fall/winter. In general, a high fraction of bacterial OTUs was found exclusively in the PA fraction (52% of total OTUs). These findings indicate that PA bacteria significantly contribute to overall bacterial richness and that they differ from FL bacteria. Therefore, to gain a deeper understanding on diversity and dynamics of aquatic bacteria, PA and FL bacteria should be generally studied independently.

No MeSH data available.