The Biogeographical Distribution of Benthic Roseobacter Group Members along a Pacific Transect Is Structured by Nutrient Availability within the Sediments and Primary Production in Different Oceanic Provinces

Abstract

By now, only limited information on the Roseobacter group thriving at the seafloor is available. Hence, the current study was conducted to determine their abundance and diversity within Pacific sediments along the 180° meridian. We hypothesize a distinct biogeographical distribution of benthic members of the Roseobacter group linked to nutrient availability within the sediments and productivity of the water column. Lowest cell numbers were counted at the edge of the south Pacific gyre and within the north Pacific gyre followed by an increase to the north with maximum values in the highly productive Bering Sea. Specific quantification of the Roseobacter group revealed on average a relative abundance of 1.7 and 6.3% as determined by catalyzed reported deposition-fluorescence in situ hybridization (CARD-FISH) and quantitative PCR (qPCR), respectively. Corresponding Illumina tag sequencing of 16S rRNA genes and 16S rRNA transcripts showed different compositions containing on average 0.7 and 0.9% Roseobacter-affiliated OTUs of the DNA- and RNA-based communities. These OTUs were mainly assigned to uncultured members of the Roseobacter group. Among those with cultured representatives, Sedimentitalea and Sulfitobacter made up the largest proportions. The different oceanic provinces with low nutrient content such as both ocean gyres were characterized by specific communities of the Roseobacter group, distinct from those of the more productive Pacific subarctic region and the Bering Sea. However, linking the community structure to specific metabolic processes at the seafloor is hampered by the dominance of so-far uncultured members of the Roseobacter group, indicating a diversity that has yet to be explored.

Impact of Phaeobacter inhibens on marine eukaryote‐associated microbial communities

“…Furthermore, TDA is likely produced in our model systems as P. inhibens DSM 17395 was pre-grown at conditions known to induce TDA production, that is, nutrient/iron rich broth. While nutrient-rich medium, such as marine broth, differs from the natural environment, some heterotrophs thrive at high nutrient levels (Alonso and Pernthaler, 2006;Pohlner et al, 2017), which are comparable to the dense, nutrient-rich surroundings of algal cells or in oysters. Henceforth, it is most likely that TDA has another function than being a broad-spectrum defence compound, and that it is probably highly dependent on the investigated conditions.…”

A Sea Change in Microbial Enzymes: Heterogeneous latitudinal and depth-related gradients in bulk water and particle-associated enzymatic activities from 30°S to 59°N in the Pacific Ocean

“…5, S5b). That the highest total organic carbon concentration exported to sediments was measured in the northernmost station of the transect (Pohlner et al 2017) indicates high particle export and transfer in the Bering Sea. As a caveat, recent findings demonstrate substantial differences in within-region particle export and transfer efficiencies (Henson et al 2019).…”

Impact of Viral Lysis on the Composition of Bacterial Communities and Dissolved Organic Matter in Deep-Sea Sediments

“…The sediment was kept in sterilized 1-L glass bottles at 4 • C in the dark until the start of the experiment in the home laboratory. Biogeochemical background data of the sediments were analyzed as described in Pohlner et al [31] ( Supplementary Table S1).…”

“…TCCs were performed using epifluorescence microscopy, following a modified protocol by Lunau et al [33] as described previously [31]. Briefly, sub-samples of the slurries were sonicated three times for 1 min, interrupted by a cooling step for 1 min.…”

“…Changes in the total and potentially active bacterial communities during the experiment were assessed by Illumina sequencing of 16S rRNA amplicons, generated from 16S rRNA genes and transcripts as described previously [31]. Briefly, DNA was extracted from 0.5 mL slurry using the DNeasy PowerSoil kit (Qiagen, Hilden, Germany) according to the manufacturer's instructions.…”