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Exo-metabolome of Pseudovibrio sp. FO-BEG1 analyzed by ultra-high resolution mass spectrometry and the effect of phosphate limitation.

Romano S, Dittmar T, Bondarev V, Weber RJ, Viant MR, Schulz-Vogt HN - PLoS ONE (2014)

Bottom Line: Oceanic dissolved organic matter (DOM) is an assemblage of reduced carbon compounds, which results from biotic and abiotic processes.Finally, we annotated the detected masses using multiple metabolite databases.These analyses suggested the presence of several masses analogue to masses of known bioactive compounds.

View Article: PubMed Central - PubMed

Affiliation: Max Planck Institute for Marine Microbiology, Bremen, Germany.

ABSTRACT
Oceanic dissolved organic matter (DOM) is an assemblage of reduced carbon compounds, which results from biotic and abiotic processes. The biotic processes consist in either release or uptake of specific molecules by marine organisms. Heterotrophic bacteria have been mostly considered to influence the DOM composition by preferential uptake of certain compounds. However, they also secrete a variety of molecules depending on physiological state, environmental and growth conditions, but so far the full set of compounds secreted by these bacteria has never been investigated. In this study, we analyzed the exo-metabolome, metabolites secreted into the environment, of the heterotrophic marine bacterium Pseudovibrio sp. FO-BEG1 via ultra-high resolution mass spectrometry, comparing phosphate limited with phosphate surplus growth conditions. Bacteria belonging to the Pseudovibrio genus have been isolated worldwide, mainly from marine invertebrates and were described as metabolically versatile Alphaproteobacteria. We show that the exo-metabolome is unexpectedly large and diverse, consisting of hundreds of compounds that differ by their molecular formulae. It is characterized by a dynamic recycling of molecules, and it is drastically affected by the physiological state of the strain. Moreover, we show that phosphate limitation greatly influences both the amount and the composition of the secreted molecules. By assigning the detected masses to general chemical categories, we observed that under phosphate surplus conditions the secreted molecules were mainly peptides and highly unsaturated compounds. In contrast, under phosphate limitation the composition of the exo-metabolome changed during bacterial growth, showing an increase in highly unsaturated, phenolic, and polyphenolic compounds. Finally, we annotated the detected masses using multiple metabolite databases. These analyses suggested the presence of several masses analogue to masses of known bioactive compounds. However, the annotation was successful only for a minor part of the detected molecules, underlining the current gap in knowledge concerning the biosynthetic ability of marine heterotrophic bacteria.

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Percentages of molecular formulae attributed to molecular categories.Only masses detected in all biological triplicates for each time point were considered.
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pone-0096038-g004: Percentages of molecular formulae attributed to molecular categories.Only masses detected in all biological triplicates for each time point were considered.

Mentions: After calculating the modified aromaticity index (AImod) we assigned the obtained molecular formulae to specific molecular categories and calculated their relative abundances at different time points (Fig. 4). In agreement with the similarity observed in the NMDS plots, at T1 the composition of the secreted metabolites was similar in both treatments. The major components of the exo-metabolome were compounds with molecular formulae assigned to peptides and highly unsaturated molecules. Only under −Pi conditions, a pronounced increase of highly unsaturated, phenolic and polyphenolic compounds and a decrease in peptides and unsaturated aliphatic compounds could be observed during stationary phase.


Exo-metabolome of Pseudovibrio sp. FO-BEG1 analyzed by ultra-high resolution mass spectrometry and the effect of phosphate limitation.

Romano S, Dittmar T, Bondarev V, Weber RJ, Viant MR, Schulz-Vogt HN - PLoS ONE (2014)

Percentages of molecular formulae attributed to molecular categories.Only masses detected in all biological triplicates for each time point were considered.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4008564&req=5

pone-0096038-g004: Percentages of molecular formulae attributed to molecular categories.Only masses detected in all biological triplicates for each time point were considered.
Mentions: After calculating the modified aromaticity index (AImod) we assigned the obtained molecular formulae to specific molecular categories and calculated their relative abundances at different time points (Fig. 4). In agreement with the similarity observed in the NMDS plots, at T1 the composition of the secreted metabolites was similar in both treatments. The major components of the exo-metabolome were compounds with molecular formulae assigned to peptides and highly unsaturated molecules. Only under −Pi conditions, a pronounced increase of highly unsaturated, phenolic and polyphenolic compounds and a decrease in peptides and unsaturated aliphatic compounds could be observed during stationary phase.

Bottom Line: Oceanic dissolved organic matter (DOM) is an assemblage of reduced carbon compounds, which results from biotic and abiotic processes.Finally, we annotated the detected masses using multiple metabolite databases.These analyses suggested the presence of several masses analogue to masses of known bioactive compounds.

View Article: PubMed Central - PubMed

Affiliation: Max Planck Institute for Marine Microbiology, Bremen, Germany.

ABSTRACT
Oceanic dissolved organic matter (DOM) is an assemblage of reduced carbon compounds, which results from biotic and abiotic processes. The biotic processes consist in either release or uptake of specific molecules by marine organisms. Heterotrophic bacteria have been mostly considered to influence the DOM composition by preferential uptake of certain compounds. However, they also secrete a variety of molecules depending on physiological state, environmental and growth conditions, but so far the full set of compounds secreted by these bacteria has never been investigated. In this study, we analyzed the exo-metabolome, metabolites secreted into the environment, of the heterotrophic marine bacterium Pseudovibrio sp. FO-BEG1 via ultra-high resolution mass spectrometry, comparing phosphate limited with phosphate surplus growth conditions. Bacteria belonging to the Pseudovibrio genus have been isolated worldwide, mainly from marine invertebrates and were described as metabolically versatile Alphaproteobacteria. We show that the exo-metabolome is unexpectedly large and diverse, consisting of hundreds of compounds that differ by their molecular formulae. It is characterized by a dynamic recycling of molecules, and it is drastically affected by the physiological state of the strain. Moreover, we show that phosphate limitation greatly influences both the amount and the composition of the secreted molecules. By assigning the detected masses to general chemical categories, we observed that under phosphate surplus conditions the secreted molecules were mainly peptides and highly unsaturated compounds. In contrast, under phosphate limitation the composition of the exo-metabolome changed during bacterial growth, showing an increase in highly unsaturated, phenolic, and polyphenolic compounds. Finally, we annotated the detected masses using multiple metabolite databases. These analyses suggested the presence of several masses analogue to masses of known bioactive compounds. However, the annotation was successful only for a minor part of the detected molecules, underlining the current gap in knowledge concerning the biosynthetic ability of marine heterotrophic bacteria.

Show MeSH
Related in: MedlinePlus