Limits...
Defence chemistry modulation by light and temperature shifts and the resulting effects on associated epibacteria of Fucus vesiculosus.

Saha M, Rempt M, Stratil SB, Wahl M, Pohnert G, Weinberger F - PLoS ONE (2014)

Bottom Line: Altogether, the effect of different treatment levels upon defence compound concentrations was limited.Nonetheless, in both experiments along with the direct influence of temperature and light, all three compounds apparently affected the overall bacterial community composition associated with F. vesiculosus since tendencies for insensitivity towards all three compounds were observed among bacterial taxa that typically dominate those communities.Given that the concentrations of at least one of the compounds (in most cases DMSP) were always high enough to inhibit bacterial settlement, we conclude that the capacity of F. vesiculosus for such defence will hardly be compromised by shading or warming to temperatures up to 25°C.

View Article: PubMed Central - PubMed

Affiliation: Department of Benthic Ecology, Helmholtz-Zentrum für Ozeanforschung (GEOMAR), Kiel, Germany.

ABSTRACT
The goals of this study were (1) to investigate whether Fucus vesiculosus regulates the production of its antifouling defence chemicals against epibacteria in response to light limitation and temperature shifts and (2) to investigate if different surface concentrations of defence compounds shape epibacterial communities. F. vesiculosus was incubated in indoor mesocosms at five different temperature conditions (5 to 25°C) and in outdoor mesocosms under six differently reduced sunlight conditions (0 to 100%), respectively. Algal surface concentrations of previously identified antifouling compounds--dimethylsulphopropionate (DMSP), fucoxanthin and proline--were determined and the bacterial community composition was characterized by in-depth sequencing of the 16S-rRNA gene. Altogether, the effect of different treatment levels upon defence compound concentrations was limited. Under all conditions DMSP alone appeared to be sufficiently concentrated to warrant for at least a partial inhibitory action against epibiotic bacteria of F. vesiculosus. In contrast, proline and fucoxanthin rarely reached the necessary concentration ranges for self-contained inhibition. Nonetheless, in both experiments along with the direct influence of temperature and light, all three compounds apparently affected the overall bacterial community composition associated with F. vesiculosus since tendencies for insensitivity towards all three compounds were observed among bacterial taxa that typically dominate those communities. Given that the concentrations of at least one of the compounds (in most cases DMSP) were always high enough to inhibit bacterial settlement, we conclude that the capacity of F. vesiculosus for such defence will hardly be compromised by shading or warming to temperatures up to 25°C.

Show MeSH
Odds for the presence of 26 different clades of bacteria within those groups of bacteria that consistently exhibited either a negative (red) or a positive (green) correlation between OTU abundance and concentration of Fucoxanthin (A), DMSP (B) and Proline (C). Geometric means of odds calculated for the temperature experiment and the light experiment ±95% confidence intervals. Asterisks indicate odds that are significantly different from 1 (χ2-test, * p<0.05, ** p<0.025, *** p<0.001).
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4215838&req=5

pone-0105333-g002: Odds for the presence of 26 different clades of bacteria within those groups of bacteria that consistently exhibited either a negative (red) or a positive (green) correlation between OTU abundance and concentration of Fucoxanthin (A), DMSP (B) and Proline (C). Geometric means of odds calculated for the temperature experiment and the light experiment ±95% confidence intervals. Asterisks indicate odds that are significantly different from 1 (χ2-test, * p<0.05, ** p<0.025, *** p<0.001).

Mentions: The distribution of many of the higher phylogenetic taxa of bacteria was not significantly different among the total bacterial community and the six subgroups of deterrent-positive or deterrent negative OTUs (Fig. 2). However, some taxa were significantly over- or underrepresented in each of these subgroups; and this was in all cases not only indicated by the χ2 statistics but also by 95% confidence intervals that excluded 1 (Fig. 2). Among the bacteria that were Fucoxanthin-positive, Flavobacteriaceae and other Flavobacteria were overrepresented, as indicated by the significantly increased odds for their presence in this subgroup (Fig. 2a). At the same time, some Flavobacteria were significantly and other Flavobacteria were non-significantly underrepresented among the bacteria that were Fucoxanthin-negative. This suggests that Flavobacteria tend to be attracted by Fucoxanthin. In contrast, Saprospiraceae, Thiotrichales and Firmicutes were significantly underrepresented in the subgroup of Fucoxanthin-positive bacteria and therefore tend not to be attracted by fucoxanthin. However, none of these taxa exhibited significantly increased odds for presence in the subgroup of Fucoxanthin-positive bacteria. Thus, fucoxanthin affected the community composition through attraction of specific taxonomic groups, as an overall deterring effect towards taxonomic groups could not be detected.


Defence chemistry modulation by light and temperature shifts and the resulting effects on associated epibacteria of Fucus vesiculosus.

Saha M, Rempt M, Stratil SB, Wahl M, Pohnert G, Weinberger F - PLoS ONE (2014)

Odds for the presence of 26 different clades of bacteria within those groups of bacteria that consistently exhibited either a negative (red) or a positive (green) correlation between OTU abundance and concentration of Fucoxanthin (A), DMSP (B) and Proline (C). Geometric means of odds calculated for the temperature experiment and the light experiment ±95% confidence intervals. Asterisks indicate odds that are significantly different from 1 (χ2-test, * p<0.05, ** p<0.025, *** p<0.001).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4215838&req=5

pone-0105333-g002: Odds for the presence of 26 different clades of bacteria within those groups of bacteria that consistently exhibited either a negative (red) or a positive (green) correlation between OTU abundance and concentration of Fucoxanthin (A), DMSP (B) and Proline (C). Geometric means of odds calculated for the temperature experiment and the light experiment ±95% confidence intervals. Asterisks indicate odds that are significantly different from 1 (χ2-test, * p<0.05, ** p<0.025, *** p<0.001).
Mentions: The distribution of many of the higher phylogenetic taxa of bacteria was not significantly different among the total bacterial community and the six subgroups of deterrent-positive or deterrent negative OTUs (Fig. 2). However, some taxa were significantly over- or underrepresented in each of these subgroups; and this was in all cases not only indicated by the χ2 statistics but also by 95% confidence intervals that excluded 1 (Fig. 2). Among the bacteria that were Fucoxanthin-positive, Flavobacteriaceae and other Flavobacteria were overrepresented, as indicated by the significantly increased odds for their presence in this subgroup (Fig. 2a). At the same time, some Flavobacteria were significantly and other Flavobacteria were non-significantly underrepresented among the bacteria that were Fucoxanthin-negative. This suggests that Flavobacteria tend to be attracted by Fucoxanthin. In contrast, Saprospiraceae, Thiotrichales and Firmicutes were significantly underrepresented in the subgroup of Fucoxanthin-positive bacteria and therefore tend not to be attracted by fucoxanthin. However, none of these taxa exhibited significantly increased odds for presence in the subgroup of Fucoxanthin-positive bacteria. Thus, fucoxanthin affected the community composition through attraction of specific taxonomic groups, as an overall deterring effect towards taxonomic groups could not be detected.

Bottom Line: Altogether, the effect of different treatment levels upon defence compound concentrations was limited.Nonetheless, in both experiments along with the direct influence of temperature and light, all three compounds apparently affected the overall bacterial community composition associated with F. vesiculosus since tendencies for insensitivity towards all three compounds were observed among bacterial taxa that typically dominate those communities.Given that the concentrations of at least one of the compounds (in most cases DMSP) were always high enough to inhibit bacterial settlement, we conclude that the capacity of F. vesiculosus for such defence will hardly be compromised by shading or warming to temperatures up to 25°C.

View Article: PubMed Central - PubMed

Affiliation: Department of Benthic Ecology, Helmholtz-Zentrum für Ozeanforschung (GEOMAR), Kiel, Germany.

ABSTRACT
The goals of this study were (1) to investigate whether Fucus vesiculosus regulates the production of its antifouling defence chemicals against epibacteria in response to light limitation and temperature shifts and (2) to investigate if different surface concentrations of defence compounds shape epibacterial communities. F. vesiculosus was incubated in indoor mesocosms at five different temperature conditions (5 to 25°C) and in outdoor mesocosms under six differently reduced sunlight conditions (0 to 100%), respectively. Algal surface concentrations of previously identified antifouling compounds--dimethylsulphopropionate (DMSP), fucoxanthin and proline--were determined and the bacterial community composition was characterized by in-depth sequencing of the 16S-rRNA gene. Altogether, the effect of different treatment levels upon defence compound concentrations was limited. Under all conditions DMSP alone appeared to be sufficiently concentrated to warrant for at least a partial inhibitory action against epibiotic bacteria of F. vesiculosus. In contrast, proline and fucoxanthin rarely reached the necessary concentration ranges for self-contained inhibition. Nonetheless, in both experiments along with the direct influence of temperature and light, all three compounds apparently affected the overall bacterial community composition associated with F. vesiculosus since tendencies for insensitivity towards all three compounds were observed among bacterial taxa that typically dominate those communities. Given that the concentrations of at least one of the compounds (in most cases DMSP) were always high enough to inhibit bacterial settlement, we conclude that the capacity of F. vesiculosus for such defence will hardly be compromised by shading or warming to temperatures up to 25°C.

Show MeSH