Temporal Variability of Coastal Planctomycetes Clades at Kabeltonne Station, North Sea

Abstract

Members of the bacterial phylum Planctomycetes are reported in marine water samples worldwide, but quantitative information is scarce. Here we investigated the phylogenetic diversity, abundance, and distribution of Planctomycetes in surface waters off the German North Sea island Helgoland during different seasons by 16S rRNA gene analysis and catalyzed reporter deposition fluorescence in situ hybridization (CARD-FISH). Generally Planctomycetes are more abundant in samples collected in summer and autumn than in samples collected in winter and spring. Statistical analysis revealed that Planctomycetes abundance was correlated to the Centrales diatom bloom in spring 2007. The analysis of size-fractionated seawater samples and of macroaggregates showed that ϳ90% of the Planctomycetes reside in the >3-m size fraction. Comparative sequence analysis of 184 almost full-length 16S rRNA genes revealed three dominant clades. The clades, named Planctomyces-related group A, uncultured Planctomycetes group B, and Pirellula-related group D, were monitored by CARD-FISH using newly developed oligonucleotide probes. All three clades showed recurrent abundance patterns during two annual sampling campaigns. Uncultured Planctomycetes group B was most abundant in autumn samples, while Planctomyces-related group A was present in high numbers only during late autumn and winter. The levels of Pirellula-related group D were more constant throughout the year, with elevated counts in summer. Our analyses suggest that the seasonal succession of the Planctomycetes is correlated with algal blooms. We hypothesize that the niche partitioning of the different clades might be caused by their algal substrates.Planctomycetes are not planktonic fungi but a monophyletic group of Bacteria drawing increasing interest for microbial ecologists as well as evolutionary and cell biologists (12). On the basis of comparative 16S rRNA gene sequence analysis, this independent phylum belongs to the so-called Planctomycetes-Verrucomicrobia-Chlamydiae (PVC) superphylum (55) that also includes the phylum Lentisphaerae, the candidate phylum Poribacteria (10), and the uncultured clade OP3. The grouping of these phyla into one superphylum is supported by unique features that distinguish its members from other members of the domain Bacteria, such as a peptidoglycan-free proteinaceous cell wall (25, 31), cellular compartmentalization (32, 33) and budding type of reproduction (12). Furthermore, Planctomycetes cells are often organized in a polar manner and attach to surfaces by nonprosthecate appendages (stalks) or holdfast structures.Although the first microscopic observation of rosette-forming "planktonic mycetes" was reported back in 1924 (58), pure cultures were not obtained until 1973 (51). Most strains have been isolated from marine, freshwater, and terrestrial habitats (2, 11, 13, 14, 26-28, 48, 57). Despite the recent success in isolating new members of the Planctomycetaceae (60), the phylum remains underrepresented in microbial culture collections. The Planctomyc...

Planctomycetes in Lakes: Poor or Strong Competitors for Phosphorus?

“…Moreover, while Planctomycetes abundances and contributions to total prokaryotic abundances in controls in our experiment 3 (e.g., from 0.87% to 1.47% [ Fig. 2A and B]) slightly increased over time and were within the range of values generally reported in aquatic ecosystems (3,4,5,6,7), those in N-amended samples decreased over time and were lower than in controls ( Fig. 2A and B).…”

“…Despite this low abundance, the role of Planctomycetes in aquatic ecosystem functioning is increasingly recognized, given their involvement in nitrogen and carbon cycling (6,8,9,10). Field studies have shown increases in abundances and changes in the composition of Planctomycetes during or after phytoplankton or cyanobacterial blooms (7,11). In line with this, studies using genomic approaches have shown that Planctomycetes possess genes involved in the degradation of plant detritus and algal polymers (12,13).…”

“…However, our findings and data from literature suggest that the responses of bacteria-wP to P additions were mainly direct effects of P (i.e., not mainly due to indirect effects of exudates released by the stimulated phytoplankton). First, if these responses were mainly due to exudates, Planctomycetes would have likely also responded, since they are known to increase during or after phytoplankton blooms in nature (7,11). Second, experimental studies using grazer-and phytoplankton-free samples (i.e., filtered on …”

“…In aquatic ecosystems, they represent between 0 and 11% of planktonic prokaryotic communities (3,4,5,6,7). Despite this low abundance, the role of Planctomycetes in aquatic ecosystem functioning is increasingly recognized, given their involvement in nitrogen and carbon cycling (6,8,9,10).…”

Vertical Distribution of Functional Potential and Active Microbial Communities in Meromictic Lake Kivu

“…4). Many studies have reported high relative abundance of Bacteroidetes or Planctomycetes following algal blooms [56][57][58][59][60]. Both phyla are known to be present and attached to aggregates, and they have various extracellular enzymes that can degrade complex organic molecules and give a competitive advantage with regards to other microbial groups [61][62][63].…”