Polysaccharide utilisation loci of Bacteroidetes from two contrasting open ocean sites in the North Atlantic.

Marine Bacteroidetes have pronounced capabilities of degrading high molecular weight organic matter such as proteins and polysaccharides. Previously we reported on 76 Bacteroidetes-affiliated fosmids from the North Atlantic Ocean's boreal polar and oligotrophic subtropical provinces. Here, we report on the analysis of further 174 fosmids from the same libraries.

Recurring patterns in bacterioplankton dynamics during coastal spring algae blooms.

A process of global importance in carbon cycling is the remineralization of algae biomass by heterotrophic bacteria, most notably during massive marine algae blooms. Such blooms can trigger secondary blooms of planktonic bacteria that consist of swift successions of distinct bacterial clades, most prominently members of the Flavobacteriia, Gammaproteobacteria and the alphaproteobacterial Roseobacter clade. We investigated such successions during spring phytoplankton blooms in the southern North Sea (German Bight) for four consecutive years.

Modification of a High-Throughput Automatic Microbial Cell Enumeration System for Shipboard Analyses.

In the age of ever-increasing "-omics" studies, the accurate and statistically robust determination of microbial cell numbers within often-complex samples remains a key task in microbial ecology. Microscopic quantification is still the only method to enumerate specific subgroups of microbial clades within complex communities by, for example, fluorescence in situ hybridization (FISH). In this study, we improved an existing automatic image acquisition and cell enumeration system and adapted it for usage at high seas on board an oceanographic research ship.

Dilution cultivation of marine heterotrophic bacteria abundant after a spring phytoplankton bloom in the North Sea.

The roles of individual bacterioplankton species in the re-mineralization of algal biomass are poorly understood. Evidence from molecular data had indicated that a spring diatom bloom in the German Bight of the North Sea in 2009 was followed by a rapid succession of uncultivated bacterioplankton species, including members of the genera Ulvibacter, Formosa, Polaribacter (class Flavobacteria) and Reinekea (class Gammaproteobacteria). We isolated strains from the same site during the diatom bloom in spring 2010 using dilution cultivation in an artificial seawater medium with micromolar substrate and nutrient concentrations.

Mapping glycoconjugate-mediated interactions of marine Bacteroidetes with diatoms.

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.

Substrate-controlled succession of marine bacterioplankton populations induced by a phytoplankton bloom.

Phytoplankton blooms characterize temperate ocean margin zones in spring. We investigated the bacterioplankton response to a diatom bloom in the North Sea and observed a dynamic succession of populations at genus-level resolution. Taxonomically distinct expressions of carbohydrate-active enzymes (transporters; in particular, TonB-dependent transporters) and phosphate acquisition strategies were found, indicating that distinct populations of Bacteroidetes, Gammaproteobacteria, and Alphaproteobacteria are specialized for successive decomposition of algal-derived organic matter.