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Aquatic Microbial Ecology

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AME 65:129-141 (2011)  -  DOI:

Abundance and diversity of Planctomycetes in a Tyrrhenian coastal system of central Italy

Ilaria Pizzetti1,2, Angélique Gobet3, Bernhard M. Fuchs1, Rudolf Amann1, Stefano Fazi2,*

1Max Planck Institute for Marine Microbiology, Celsiusstr. 1, 28359 Bremen, Germany
2Water Research Institute (IRSA-CNR), via Salaria km 29.300, 00015 Monterotondo, Roma, Italy
3Station Biologique de Roscoff, UMR 7144, CNRS et Université Pierre et Marie Curie (UPMC), Place Georges Teissier, 29680 Roscoff, France

ABSTRACT: The phylum Planctomycetes is involved in important processes, such as the mineralization of algal biomass and the removal of nitrogen. Using a combination of 16S rRNA sequence analysis and in situ hybridization, we analyzed the diversity and dynamics of Planctomycetes in a shallow meso-eutrophic lake, Lago di Paola, Italy. Planctomycetes detected by the probe PLA46 accounted for 1 to 5% of prokaryotic picoplankton. Abundances were higher in the coastal lake than in the adjacent marine waters. In the surface waters of the lake, the numbers of Planctomycetes fluctuated greatly, reaching a maximum of 1.5 × 106 cells ml−1 in July. The hypoxic bottom waters had less variable cell abundances. The Planctomycetes counts were positively correlated with chlorophyll a concentrations, confirming the role of this phylum in the degradation of algal biomass. We obtained 70 almost full-length 16S rRNA gene sequences of Planctomycetes from 2 libraries. Four distinct clades could be identified. The Pirellula-related group F and the uncultured Planctomycetes group B both had the highest identity with sequences retrieved from marine habitats, whereas the Pirellula-related group E was affiliated with sequences known from freshwater and brackish water environments. The Planctomyces-related group A seems to have a wide habitat range. Catalyzed reported deposition fluorescence in situ hybridization with newly developed probes revealed abundances of the 4 clades in surface and bottom waters ranging from 1 × 103 to 5 × 104 cells ml−1. Together, the 4 clade-specific probes identified only about a quarter of the Planctomycetes detected by probe PLA46. This indicates that the diversity of Planctomycetes has not yet been fully explored.

KEY WORDS: Coastal lake ecology · Planctomycetes · Bacterial diversity · FISH · CARD-FISH · 16S rRNA gene sequencing

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Cite this article as: Pizzetti I, Gobet A, Fuchs BM, Amann R, Fazi S (2011) Abundance and diversity of Planctomycetes in a Tyrrhenian coastal system of central Italy. Aquat Microb Ecol 65:129-141.

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