Effect of P depletion on the functional pools of diatom carbohydrates, and their utilization by bacterial communities

Type Article
Date 2020-05
Language English
Author(s) Labry ClaireORCID1, Delmas Daniel1, Moriceau Brivaela2, Gallinari Morgane3, Quere Julien1, Youenou Agnes1
Affiliation(s) 1 : Ifremer, DYNECO, F-29280 Plouzané, France
2 : Univ Brest, CNRS, IRD, Ifremer, LEMAR, F-29280 Plouzané, France
3 : Univ Brest, CNRS, IRD, Ifremer, LEMAR, F-29280 Plouzané, France
Source Marine Ecology Progress Series (0171-8630) (Inter-Research Science Center), 2020-05 , Vol. 641 , P. 49-62
DOI 10.3354/meps13297
WOS© Times Cited 1
Keyword(s) P limitation, Phytoplankton, Diatom, Bacteria, Mineralization, Carbohydrate, Glucosidase
Abstract

Phosphorus (P) limitation of phytoplankton growth is known to affect the accumulation and release of carbohydrates (CHO) by micro-algae. However, relatively little is known about the fate of algal exudates, notably their bacterial degradation. The CHO chemical characterization is also not exhaustive, especially in ‘functional’ pools relevant for phytoplankton physiology (particulate reserve [R] or structural [S] CHO) and for bacterial degradation (dissolved mono- [MDCHO] and polysaccharides [P-DCHO]). In this study, we investigated how P depletion and repletion affect the CHO composition in diatom Thalassiosira weissflogii cultures, and the shortterm response of free and diatom-attached bacteria in terms of abundance and potential βglucosidase activity (βGlc). The bacterial inoculum was composed of the bacterial consortiums of diatom precultures and a natural bacterial community from the Bay of Brest. P depletion favored CHO accumulation in diatom cells, mainly as R i.e. soluble CHO accumulated in cytoplasm, but also as S, polysaccharides linked to the cell wall. The R:S ratio was high in the present diatom cultures. The high M-DCHO observed in P-deplete cultures (twice that of P-replete cultures) when P-DCHO remained quite similar is explained both by active polysaccharide hydrolysis (very high potential βGlc of attached bacteria) and reduced uptake of M-DCHO by Pdepleted bacteria. P depletion of heterotrophic bacteria favors labile CHO accumulation, which may affect particle potential aggregation. However, the remarkably constant M-DCHO concentration over time for both conditions suggests tight coupling between phytoplankton accumulation, release, polymer hydrolysis and monomer uptake by bacteria.

Full Text
File Pages Size Access
14 948 KB Embargo until 2025-05-07
Author's final draft 43 1 MB Open access
Top of the page

How to cite 

Labry Claire, Delmas Daniel, Moriceau Brivaela, Gallinari Morgane, Quere Julien, Youenou Agnes (2020). Effect of P depletion on the functional pools of diatom carbohydrates, and their utilization by bacterial communities. Marine Ecology Progress Series, 641, 49-62. Publisher's official version : https://doi.org/10.3354/meps13297 , Open Access version : https://archimer.ifremer.fr/doc/00628/74045/