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Applied and Environmental Microbiology, July 1999, p. 3164-3174, Vol. 65, No. 7
GBF-National Research Centre for
Biotechnology, Division of Microbiology, Microbial Ecology Group,
D-38124 Braunschweig, Germany
Received 23 December 1998/Accepted 20 April 1999
Community structure of bacterioplankton was studied during the
major growth season for phytoplankton (April to October) in the
epilimnion of a temperate eutrophic lake (Lake Plußsee, northern Germany) by using comparative 5S rRNA analysis. Estimates of the relative abundances of single taxonomic groups were made on the basis
of the amounts of single 5S rRNA bands obtained after high-resolution electrophoresis of RNA directly from the bacterioplankton.
Full-sequence analysis of single environmental 5S rRNAs enabled the
identification of single taxonomic groups of bacteria. Comparison of
partial 5S rRNA sequences allowed the detection of changes of single
taxa over time. Overall, the whole bacterioplankton community showed two to eight abundant (>4% of the total 5S rRNA) taxa. A distinctive seasonal succession was observed in the taxonomic structure of this
pelagic community. A rather-stable community structure, with seven to
eight different taxonomic units, was observed beginning in April during
the spring phytoplankton bloom. A strong reduction in this diversity
occurred at the beginning of the clear-water phase (early May), when
only two to four abundant taxa were observed, with one taxon dominating
(up to 72% of the total 5S rRNA). The community structure during
summer stagnation (June and July) was characterized by frequent changes
of different dominating taxa. During late summer, a dinoflagellate
bloom (Ceratium hirudinella) occurred, with Comamonas
acidovorans (
0099-2240/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
Seasonal Dynamics of Bacterioplankton Community
Structure in a Eutrophic Lake as Determined by 5S rRNA
Analysis
-subclass of the class Proteobacteria) becoming the dominant bacterial species
(average abundance of 43% of the total 5S rRNA). Finally, the seasonal dynamics of the community structure of bacterioplankton were compared with the abundances of other major groups of the aquatic food web, such
as phyto- and zooplankton, revealing that strong grazing pressure by
zooplankton can reduce microbial diversity substantially in pelagic environments.
*
Corresponding author. Mailing address: GBF-National
Research Centre for Biotechnology, Division of Microbiology, Microbial Ecology Group, Mascheroder Weg 1, D-38124 Braunschweig, Germany. Phone:
49-531-6181-419. Fax: 49-531-6181-411. E-mail: mho{at}gbf.de.
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