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Functional and compositional succession of bacterioplankton in response to a gradient in bioavailable dissolved organic carbon
Author(s) -
Dinasquet Julie,
Kragh Theis,
Schrøter MarieLouise,
Søndergaard Morten,
Riemann Lasse
Publication year - 2013
Publication title -
environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.954
H-Index - 188
eISSN - 1462-2920
pISSN - 1462-2912
DOI - 10.1111/1462-2920.12178
Subject(s) - bacterioplankton , dissolved organic carbon , biology , microbial population biology , environmental chemistry , nutrient , ecology , bacteria , chemistry , phytoplankton , genetics
Summary Studies indicate that bacterial taxa utilize different fractions of the dissolved organic carbon ( DOC ) pool, while others suggest functional redundancy among constituents of bacterioplankton, implying only a weak coupling between community structure and function. We examined bacterial compositional and functional [ectoenzymatic activities and growth efficiency; bacterial growth efficiency ( BGE )] responses to a gradient in bioavailable DOC ( bDOC ). This was achieved over 10 days in DOC utilization assays containing Baltic Sea water with variable amounts of natural bDOC . Measurements of bacterial growth, O 2 and DOC consumption in the assays using non‐invasive sampling showed that BGE changed over time and that the bDOC utilized accounted for 4–13% of the DOC pool. Pyrosequencing of 16S rRNA genes demonstrated minor differences at the phylum level between samples, whereas larger successional differences were discernible at lower phylogenetic levels. Our study suggests that changes in concentrations of bDOC affect bacterioplankton BGE and community structure by selecting for some taxa while the relative abundance of most taxa remained unaffected. Ectoenzymes activities suggested preferential degradation of protein‐rich compounds by bacteria, switching to carbohydrate‐rich DOC when proteins were depleted. Hence, there was a fairly weak linkage between bacterial community composition and DOC utilization suggesting that overall bacterioplankton community structure only to some extent has predictive power for processing of the DOC pool.