Pernthaler, J. Max-Planck Institute for Marine Microbiology, email@example.com
Amann, R. Max-Planck Institute for Marine Microbiology, firstname.lastname@example.org
BIOMASSES OF SPECIFIC BACTERIAL POPULATIONS IN THE PLANKTON: COMBINING WHOLE CELL IDENTIFICATION AND IMAGE ANALYZED MICROSCOPY
In contrast to their physiological and phylogenetic diversity, pelagic bacteria generally show little morphological complexity. This lack of conspicuous shapes has mainly been discussed as an obstacle for any microscopy-based classification of aquatic microbes. Morphometry of single bacterial cells has however proven valuable for rapid estimation of microbial biomass, and the simple geometry of bacterial cells facilitates quantification by computer-assisted image analysis. Whole cell fluorescence in situ hybridization (FISH) with rRNA-targeted oligonucleotide probes is an emerging molecular staining technique which selectively visualizes bacterial cells of defined phylogenetic affiliation. So far FISH has been successfully applied both in marine and freshwater pelagic habitats. In combination with image cytometry, the cell size distributions, and potentially the per cell DNA and RNA contents of specific compartments of heterotrophic pelagic microbial communities can be determined. It has therefore become feasable to search for those bacteria that constitute the important fractions of microbial biomass and organic carbon in the plankton. Moreover, as the cell size distributions of individual species are related to basic features of their cell cycle, morphometric data may allow the study of demographic parameters of bacterial populations in the context of competition and food web structure.
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