Summary The marine bacterium A lteromonas macleodii is a copiotrophic r ‐strategist, but little is known about its potential to degrade polysaccharides. Here, we studied the degradation of alginate and other algal polysaccharides by A . macleodii strain 83‐1 in comparison to other A . macleodii strains. Cell densities of strain 83‐1 with alginate as sole carbon source were comparable to those with glucose, but the exponential...

Summary The bacterial degradation of polysaccharides is central to marine carbon cycling, but little is known about the bacterial taxa that degrade specific marine polysaccharides. Here, bacterial growth and community dynamics were studied during the degradation of the polysaccharides chitin, alginate and agarose in microcosm experiments at four contrasting locations in the S outhern and A tlantic O ceans. At the Southern pola...

Summary We assessed the composition of the bacterioplankton in the Atlantic sector of the Southern Ocean in austral fall and winter and in New Zealand coastal waters in summer. The various water masses between the subtropics/Agulhas–Benguela boundary region and the Antarctic coastal current exhibited distinct bacterioplankton communities with the highest richness in the polar frontal region, as shown by denaturing gradient gel...

Summary Gram positive bacteria recently have been identified as important components of freshwater ecosystems and are also present in marine environments. However, their quantitative significance and possible role in the latter systems is still little studied, in particular in coastal regions. Therefore, we investigated the abundance and composition of Gram positive bacteria in the Wadden Sea, a tidal flat ecosystem in the Ger...

Summary We examined bacterial dynamics in batch cultures of two axenic marine diatoms ( Thalassiosira rotula and Skeletonema costatum ). The axenic diatoms were inoculated with natural bacterial assemblages and monitored by 4,6‐diamidino‐2‐phenolindole (DAPI) counts, denaturing gradient gel electrophoresis (DGGE) with subsequent analysis of excised, sequenced 16S rRNA gene fragments, and fluorescence in situ hybridization (FIS...

Tidal flat ecosystems are highly dynamic environments with tremendous short‐term and long‐term changes in physical, chemical, and biological properties. We measured salinity, temperature, oxygen, dry weight (dry wt), inorganic (PIC) and organic carbon (POC) fractions of suspended particulate matter (SPM), and chlorophyll a (Chl a ); counted numbers of free‐living and particle‐associated bacteria; and measured dissolved amino a...