Mapping glycoconjugate-mediated interactions of marine Bacteroidetes with diatoms

Abstract

The degradation of diatoms is mainly catalyzed by Bacteroidetes and this process is of global relevance for the carbon cycle. In this study, a combination of catalyzed reporter deposition-fluorescence in situ hybridization (CARD-FISH) and fluorescent lectin binding analysis (FLBA) was used to identify and map glycoconjugates involved in the specific interactions of Bacteroidetes and diatoms, as well as detritus, at the coastal marine site Helgoland Roads (German Bight, North Sea). The study probed both the presence of lectin-specific extracellular polymeric substances (EPS) of Bacteroidetes for cell attachment and that of glycoconjugates on diatoms with respect to binding sites for Bacteroidetes. Members of the clades Polaribacter and Ulvibacter were shown to form microcolonies within aggregates for which FLBA indicated the presence of galactose containing slime. Polaribacter spp. was shown to bind specifically to the setae of the abundant diatom Chaetoceros spp., and the setae were stained with fucose-specific lectins. In contrast, Ulvibacter spp. attached to diatoms of the genus Asterionella which bound, among others, the mannose-specific lectin PSA. The newly developed CARD-FISH/FLBA protocol was limited to the glycoconjugates that persisted after the initial CARD-FISH procedure. The differential attachment of bacteroidetal clades to diatoms and their discrete staining by FLBA provided evidence for the essential role that formation and recognition of glycoconjugates play in the interaction of bacteria with phytoplankton.

Embedding and slicing of intact in situ collected marine snow

“…For staining procedures involving multiple staining and washing steps, agarose‐embedding of sections added structural stability and improved section integrity and preservation. However, agarose‐embedding is limited by non‐specific binding to agarose by lectins (as observed in our study and reported by Bennke et al ). Staining prior to embedding in cryogel may be considered to sidestep this problem, but limits the possibility of combining incompatible stains across consecutive slices and excludes aggregates embedded in situ.…”

Niches of two polysaccharide-degrading Polaribacter isolates from the North Sea during a spring diatom bloom

“…Association of Polaribacter spp. with phytoplankton was also observed in the open North Atlantic (Gó mez-Pereira et al, 2012) and the coastal North Sea (Bennke et al, 2013) and has been inferred in a recent study on an Antarctic polynya (Kim et al, 2013). Because of their presence in cold and temperate waters, in oligotrophic and copiotrophic nutrient regimes within open ocean and coastal zones, members of the genus Polaribacter have recently been recognized as 'widely distributed in marine habitats' (Nedashkovskaya et al, 2013).…”

Microbial dynamics during harmful dinoflagellate Ostreopsis cf. ovata growth: Bacterial succession and viral abundance pattern

“…These findings imply a possible relevance of this bimodal interaction in algal bloom initiation and termination (Riclea et al., ; Wang et al., ), especially once the dominance of the same phylotypes is assessed in the bacterial communities associated with both bloom phases. In addition, quality and amount of the algal‐released compounds, that depend on algal species and its physiological status, would define phylogenetic structure (Bennke, Neu, Fuchs, & Amann, ; Christie‐Oleza, Scanlan, & Armengaud, ; Xing et al., ) and successional pattern of the associated bacterial community (e.g., Bagatini et al., ; Grossart et al., ; Teeling et al., ).…”