Differential Growth Response of Colony-Forming α- and γ-Proteobacteria in Dilution Culture and Nutrient Addition Experiments from Lake Kinneret (Israel), the Eastern Mediterranean Sea, and the Gulf of Eilat
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Media type:
E-Article
Title:
Differential Growth Response of Colony-Forming α- and γ-Proteobacteria in Dilution Culture and Nutrient Addition Experiments from Lake Kinneret (Israel), the Eastern Mediterranean Sea, and the Gulf of Eilat
Contributor:
Pinhassi, Jarone;
Berman, Tom
imprint:
American Society for Microbiology, 2003
Published in:Applied and Environmental Microbiology
Language:
English
DOI:
10.1128/aem.69.1.199-211.2003
ISSN:
0099-2240;
1098-5336
Origination:
Footnote:
Description:
<jats:title>ABSTRACT</jats:title>
<jats:p>
Even though it is widely accepted that bacterioplankton growth in lakes and marine ecosystems is determined by the trophic status of the systems, knowledge of the relationship between nutrient concentrations and growth of particular bacterial species is almost nonexistent. To address this question, we performed a series of culture experiments with water from Lake Kinneret (Israel), the eastern Mediterranean Sea, and the Gulf of Eilat (northern Red Sea). In the initial water samples, the proportion of CFU was typically <0.002% of the 4′,6′-diamidino-2-phenylindole (DAPI) counts. During incubation until the early stationary phase, the proportion of CFU increased to 20% of the DAPI counts and to 2 to 15% of the DAPI counts in unenriched lake water and seawater dilution cultures, respectively. Sequencing of the 16S ribosomal DNA of colony-forming bacteria in these cultures consistently revealed an abundance of α-proteobacteria, but notable phylogenetic differences were found at the genus level. Marine dilution cultures were dominated by bacteria in the
<jats:italic>Roseobacter</jats:italic>
clade, while lake dilution cultures were dominated by bacteria affiliated with the genera
<jats:italic>Sphingomonas</jats:italic>
and
<jats:italic>Caulobacter</jats:italic>
. In nutrient (glucose, ammonium, phosphate) addition experiments the CFU comprised 20 to 83% of the newly grown cells. In these incubation experiments fast-growing γ-proteobacteria dominated; in the marine experiments primarily different
<jats:italic>Vibrio</jats:italic>
and
<jats:italic>Alteromonas</jats:italic>
species appeared, while in the lake water experiments species of the genera
<jats:italic>Shewanella</jats:italic>
,
<jats:italic>Aeromonas</jats:italic>
, and
<jats:italic>Rheinheimera</jats:italic>
grew. These results suggest that major, but different, γ-proteobacterial genera in both freshwater and marine environments have a preference for elevated concentrations of nutrients and easily assimilated organic carbon sources but are selectively outcompeted by α-proteobacteria in the presence of low nutrient concentrations.
</jats:p>