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Distinct dissolved organic matter sources induce rapid transcriptional responses in coexisting populations of P rochlorococcus , P elagibacter and the OM60 clade
Author(s) -
Sharma Adrian K.,
Becker Jamie W.,
Ottesen Elizabeth A.,
Bryant Jessica A.,
Duhamel Solange,
Karl David M.,
Cordero Otto X.,
Repeta Daniel J.,
DeLong Edward F.
Publication year - 2014
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 - 10.1111/1462-2920.12254
Subject(s) - dissolved organic carbon , biology , axenic , prochlorococcus , organic matter , environmental chemistry , seawater , gammaproteobacteria , bacterioplankton , biogeochemical cycle , alteromonas , plankton , ecology , biochemistry , bacteria , cyanobacteria , phytoplankton , chemistry , nutrient , gene , synechococcus , genetics , 16s ribosomal rna
Summary A considerable fraction of the E arth's organic carbon exists in dissolved form in seawater. To investigate the roles of planktonic marine microbes in the biogeochemical cycling of this dissolved organic matter ( DOM ), we performed controlled seawater incubation experiments and followed the responses of an oligotrophic surface water microbial assemblage to perturbations with DOM derived from an axenic culture of P rochlorococcus , or high‐molecular weight DOM concentrated from nearby surface waters. The rapid transcriptional responses of both P rochlorococcus and P elagibacter populations suggested the utilization of organic nitrogen compounds common to both DOM treatments. Along with these responses, both populations demonstrated decreases in gene transcripts associated with nitrogen stress, including those involved in ammonium acquisition. In contrast, responses from low abundance organisms of the NOR5/OM60 gammaproteobacteria were observed later in the experiment, and included elevated levels of gene transcripts associated with polysaccharide uptake and oxidation. In total, these results suggest that numerically dominant oligotrophic microbes rapidly acquire nitrogen from commonly available organic sources, and also point to an important role for carbohydrates found within the DOM pool for sustaining the less abundant microorganisms in these oligotrophic systems.