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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.


Taxonomy Plot. Cumulative bar charts comparing relative class abundances in particle-attached (PA) and free-living (FL) bacteria in samples of summer (A) and winter (B).
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Figure 4: Taxonomy Plot. Cumulative bar charts comparing relative class abundances in particle-attached (PA) and free-living (FL) bacteria in samples of summer (A) and winter (B).

Mentions: The β-diversity indices measure the similarity (or dissimilarity) in microbiome composition between samples. At all stations, bacterial communities in Baltic surface waters revealed a higher OTU richness in fall/winter than in summer (Figure 3). The dominant bacterial communities (≥1% of total bacteria) (Figure 4) were Alpha−, Beta−, Gamma−, and Deltaproteobacteria as well as Bacteriodetes. Also Flavobacteria, Actinobacteria, Planctomycetes, Cyaonobacteria, and Verrucomicrobia occurred at all stations. Deferribacteres, Firmicutes, and Spirochaetae were present only at the marine station, whereas Chloroflexi were found at the marine and oligohaline station. Chlorobi were detected at the meso- and oligohaline stations. Acidobacteria, Chlamydiae, and Candidate division OD1 were exclusively found at the oligohaline station in fall/winter. Richness was lower in summer than in fall/winter since Firmicutes, Deferribacteres, Chloroflexi, Spirochaetae, and Chlorobi did not occur and Deltaproteobacteria and Verrucomicrobia were less abundant at the mesohaline station. Only the oligohaline station revealed no considerable difference between winter and summer.


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)

Taxonomy Plot. Cumulative bar charts comparing relative class abundances in particle-attached (PA) and free-living (FL) bacteria in samples of summer (A) and winter (B).
© Copyright Policy
Related In: Results  -  Collection

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

Figure 4: Taxonomy Plot. Cumulative bar charts comparing relative class abundances in particle-attached (PA) and free-living (FL) bacteria in samples of summer (A) and winter (B).
Mentions: The β-diversity indices measure the similarity (or dissimilarity) in microbiome composition between samples. At all stations, bacterial communities in Baltic surface waters revealed a higher OTU richness in fall/winter than in summer (Figure 3). The dominant bacterial communities (≥1% of total bacteria) (Figure 4) were Alpha−, Beta−, Gamma−, and Deltaproteobacteria as well as Bacteriodetes. Also Flavobacteria, Actinobacteria, Planctomycetes, Cyaonobacteria, and Verrucomicrobia occurred at all stations. Deferribacteres, Firmicutes, and Spirochaetae were present only at the marine station, whereas Chloroflexi were found at the marine and oligohaline station. Chlorobi were detected at the meso- and oligohaline stations. Acidobacteria, Chlamydiae, and Candidate division OD1 were exclusively found at the oligohaline station in fall/winter. Richness was lower in summer than in fall/winter since Firmicutes, Deferribacteres, Chloroflexi, Spirochaetae, and Chlorobi did not occur and Deltaproteobacteria and Verrucomicrobia were less abundant at the mesohaline station. Only the oligohaline station revealed no considerable difference between winter and summer.

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.