Cross-domain diversity effects: linking diatom species richness, intraspecific richness, and biomass production to host-associated bacterial diversity.

Interactions between bacteria and microalgae are important for the functioning of aquatic ecosystems, yet interactions based on the biodiversity of these two taxonomic domains have been scarcely studied. Specifically, it is unclear whether a positive biodiversity-productivity relationship in phytoplankton is largely facilitated by niche partitioning among the phytoplankton organisms themselves or whether associated bacterial communities play an additional role in modifying these diversity effects. Moreover, the effects of intraspecific diversity in phytoplankton communities on bacterial community diversity have not been tested.

Biogeography of , description of a new strain isolated from the North Sea and emended genus and species descriptions.

A new heterotrophic, aerobic alphaproteobacterium, designated strain SH36 (=DSM 23330=LMG 25292), was obtained from a seawater sample collected in the open North Sea during a phytoplankton bloom. Analysis of the 16S rRNA gene sequence revealed affiliation of strain SH36 to the species (family ), showing 100 and 99.9 % sequence similarity to the 16S rRNA genes of the strains ZXM098 and ZXM100.

Distinct bacterial succession and functional response to alginate in the South, Equatorial, and North Pacific Ocean.

The availability of alginate, an abundant macroalgal polysaccharide, induces compositional and functional responses among marine microbes, but these dynamics have not been characterized across the Pacific Ocean. We investigated alginate-induced compositional and functional shifts (e.g.

Ecogenomics and cultivation reveal distinctive viral-bacterial communities in the surface microlayer of a Baltic Sea slick.

Visible surface films, termed slicks, can extensively cover freshwater and marine ecosystems, with coastal regions being particularly susceptible to their presence. The sea-surface microlayer (SML), the upper 1-mm at the air-water interface in slicks (herein slick SML) harbors a distinctive bacterial community, but generally little is known about SML viruses. Using flow cytometry, metagenomics, and cultivation, we characterized viruses and bacteria in a brackish slick SML in comparison to non-slick SML as well as seawater below slick and non-slick areas (subsurface water = SSW).

Sea foams are ephemeral hotspots for distinctive bacterial communities contrasting sea-surface microlayer and underlying surface water.

The occurrence of foams at oceans' surfaces is patchy and generally short-lived, but a detailed understanding of bacterial communities inhabiting sea foams is lacking. Here, we investigated how marine foams differ from the sea-surface microlayer (SML), a <1-mm-thick layer at the air-sea interface, and underlying water from 1 m depth. Samples of sea foams, SML and underlying water collected from the North Sea and Timor Sea indicated that foams were often characterized by a high abundance of small eukaryotic phototrophic and prokaryotic cells as well as a high concentration of surface-active substances (SAS).

Lipidomic Analysis of Roseobacters of the Pelagic RCA Cluster and Their Response to Phosphorus Limitation.

The marine roseobacter-clade affiliated cluster (RCA) represents one of the most abundant groups of bacterioplankton in the global oceans, particularly in temperate and sub-polar regions. They play a key role in the biogeochemical cycling of various elements and are important players in oceanic climate-active trace gas metabolism. In contrast to copiotrophic roseobacter counterparts such as DSS-3 and sp.

Distinct relationships between fluorescence in situ hybridization and 16S rRNA gene- and amplicon-based sequencing data of bacterioplankton lineages.

Catalyzed reporter deposition fluorescence in situ hybridization (CARD-FISH) and amplicon sequencing of the total (16S rRNA gene) and potentially active (16S rRNA transcripts), community are the major state of the art approaches for assessing the composition of bacterial communities in marine pelagic and other ecosystems. However, CARD-FISH and amplicon sequencing methods have not yet been directly compared to assess the composition of bacterioplankton communities. Therefore, these approaches were used to study the composition of bacterial communities in two North Sea seawater mesocosm experiments supplemented with diatom-derived organic matter (OM).

Complementary energy acquisition via aerobic anoxygenic photosynthesis and carbon monoxide oxidation by Planktomarina temperata of the Roseobacter group.

In marine pelagic ecosystems energy is often the limiting factor for growth of heterotrophic bacteria. Aerobic anoxygenic photosynthesis (AAP) and oxidation of carbon monoxide (CO) are modes to acquire complementary energy, but their significance in abundant and characteristic pelagic marine bacteria has not been well studied. In long-term batch culture experiments we found that Planktomarina temperata RCA23, representing the largest and most prominent subcluster of the Roseobacter group, maintains 2-3-fold higher cell numbers in the stationary and declining phase when grown in a light-dark cycle relative to dark conditions.

Distinct biogeographic patterns of bacterioplankton composition and single-cell activity between the subtropics and Antarctica.

Bacterial biogeography and activity in the Southern Ocean are poorly understood to date. Here, we applied CARD-FISH to quantify bacterial community structure from the subtropics to Antarctica between 10°W and 10°E, covering four biogeographic provinces with distinct environmental properties. In addition, incorporation of radiolabeled glucose, amino acids and leucine via MAR-FISH served to quantify the contribution to substrate turnover by selected bacterial groups.

Tritonibacter horizontis gen. nov., sp. nov., a member of the Rhodobacteraceae, isolated from the Deepwater Horizon oil spill.

A heterotrophic, Gram-stain-negative, aerobic, sodium-requiring and motile bacterium was isolated from oil-contaminated surface water of the Gulf of Mexico during the Deepwater Horizon oil spill. Strain O3.65 showed highest 16S rRNA gene sequence similarity to Phaeobacter gallaeciensis BS107 and Phaeobacter inhibens T5, both with 98.

Linking Compositional and Functional Predictions to Decipher the Biogeochemical Significance in DFAA Turnover of Abundant Bacterioplankton Lineages in the North Sea.

Deciphering the ecological traits of abundant marine bacteria is a major challenge in marine microbial ecology. In the current study, we linked compositional and functional predictions to elucidate such traits for abundant bacterioplankton lineages in the North Sea. For this purpose, we investigated entire and active bacterioplankton composition along a transect ranging from the German Bight to the northern North Sea by pyrotag sequencing of bacterial 16S rRNA genes and transcripts.

Composition of Total and Cell-Proliferating Bacterioplankton Community in Early Summer in the North Sea - Roseobacters Are the Most Active Component.

Heterotrophic bacterioplankton communities play an important role in organic matter processing in the oceans worldwide. In order to investigate the significance of distinct phylogenetic bacterial groups it is not only important to assess their quantitative abundance but also their growth dynamics in relation to the entire bacterioplankton. Therefore bacterial abundance, biomass production and the composition of the entire and cell-proliferating bacterioplankton community were assessed in North Sea surface waters between the German Bight and 58°N in early summer by applying catalyzed reporter deposition (CARD-FISH) and bromodeoxyuridine fluorescence hybridization (BrdU-FISH).

Cutting through the smoke: the diversity of microorganisms in deep-sea hydrothermal plumes.

There are still notable gaps regarding the detailed distribution of microorganisms between and within insular habitats such as deep-sea hydrothermal vents. This study investigates the community composition of black smoker vent microorganisms in the Southern Hemisphere, and changes thereof along a spatial and chemical gradient ranging from the vent plume to surrounding waters. We sampled two hydrothermal vent fields, one at the South West Indian Ridge (SWIR), the other at the East Scotia Ridge (ESR).

High wind speeds prevent formation of a distinct bacterioneuston community in the sea-surface microlayer.

The sea-surface microlayer (SML) at the boundary between atmosphere and hydrosphere represents a demanding habitat for bacteria. Wind speed is a crucial but poorly studied factor for its physical integrity. Increasing atmospheric burden of CO2, as suggested for future climate scenarios, may particularly act on this habitat at the air-sea interface.

Draft genome sequence of the marine strain O3.65, cultivated from oil-polluted seawater of the Deepwater Horizon oil spill.

The marine alphaproteobacterium strain O3.65 was isolated from an enrichment culture of surface seawater contaminated with weathered oil (slicks) from the Deepwater Horizon (DWH) oil spill and belongs to the ubiquitous, diverse and ecological relevant group within the . Here, we present a preliminary set of physiological features of strain O3.

Biogeography and environmental genomics of the Roseobacter-affiliated pelagic CHAB-I-5 lineage.

The identification and functional characterization of microbial communities remains a prevailing topic in microbial oceanography as information on environmentally relevant pelagic prokaryotes is still limited. The Roseobacter group, an abundant lineage of marine Alphaproteobacteria, can constitute large proportions of the bacterioplankton. Roseobacters also occur associated with eukaryotic organisms and possess streamlined as well as larger genomes from 2.

Co-occurrence Analysis of Microbial Taxa in the Atlantic Ocean Reveals High Connectivity in the Free-Living Bacterioplankton.

We determined the taxonomic composition of the bacterioplankton of the epipelagic zone of the Atlantic Ocean along a latitudinal transect (51°S-47°N) using Illumina sequencing of the V5-V6 region of the 16S rRNA gene and inferred co-occurrence networks. Bacterioplankon community composition was distinct for Longhurstian provinces and water depth. Free-living microbial communities (between 0.

Bacterioplankton Biogeography of the Atlantic Ocean: A Case Study of the Distance-Decay Relationship.

In order to determine the influence of geographical distance, depth, and Longhurstian province on bacterial community composition and compare it with the composition of photosynthetic micro-eukaryote communities, 382 samples from a depth-resolved latitudinal transect (51°S-47°N) from the epipelagic zone of the Atlantic ocean were analyzed by Illumina amplicon sequencing. In the upper 100 m of the ocean, community similarity decreased toward the equator for 6000 km, but subsequently increased again, reaching similarity values of 40-60% for samples that were separated by ~12,000 km, resulting in a U-shaped distance-decay curve. We conclude that adaptation to local conditions can override the linear distance-decay relationship in the upper epipelagial of the Atlantic Ocean which is apparently not restrained by barriers to dispersal, since the same taxa were shared between the most distant communities.

Different utilization of alginate and other algal polysaccharides by marine Alteromonas macleodii ecotypes.

The marine bacterium Alteromonas 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.

Description of Octadecabacter temperatus sp. nov., isolated from the southern North Sea, emended descriptions of the genus Octadecabacter and its species and reclassification of Octadecabacter jejudonensisPark and Yoon 2014 as Pseudooctadecabacter jejudonensis gen. nov., comb. nov.

A heterotrophic, Gram-negative, aerobic bacterium, designated strain SB1T, was isolated from surface water of the southern North Sea. Comparison of 16S rRNA gene sequences revealed that strain SB1T is affiliated to the genus Octadecabacter within the marine Roseobacter clade (family Rhodobacteraceae), with Octadecabacter antarcticus as the closest described species (98.2 % sequence similarity to the type strain).

Bacterial community dynamics during polysaccharide degradation at contrasting sites in the Southern and Atlantic Oceans.

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 Southern and Atlantic Oceans. At the Southern polar front, chitin-supplemented microcosms were characterized by higher fractions of actively growing cells and a community shift from Alphaproteobacteria to Gammaproteobacteria and Bacteroidetes.

Adaptation of an abundant Roseobacter RCA organism to pelagic systems revealed by genomic and transcriptomic analyses.

The RCA (Roseobacter clade affiliated) cluster, with an internal 16S rRNA gene sequence similarity of >98%, is the largest cluster of the marine Roseobacter clade and most abundant in temperate to (sub)polar oceans, constituting up to 35% of total bacterioplankton. The genome analysis of the first described species of the RCA cluster, Planktomarina temperata RCA23, revealed that this phylogenetic lineage is deeply branching within the Roseobacter clade. It shares not >65.