Bacterial diversity in the oxygen minimum zone of the eastern tropical South Pacific

Abstract

The structure and diversity of bacterial communities associated with the oxygen minimum zone (OMZ) of the eastern tropical South Pacific was studied through phylogenetic analysis. Clone libraries of 16S rRNA gene fragments were constructed using environmental DNA collected from the OMZ (60 m and 200 m), the sea surface (10 m), and the deep oxycline (450 m). At the class level, the majority of sequences affiliated to the gamma- (53.7%) and alpha-Proteobacteria (19.7%), and to the Bacteroidetes (11.2%). A vertical partitioning of the bacterial communities was observed, with main differences between the suboxic OMZ and the more oxygenated surface and deep oxycline waters. At the surface, the microbial community was predominantly characterized by SAR86, Loktanella and unclassified Flavobacteriaceae, whereas the deeper layer was dominated by Sulfitobacter and unclassified Alteromonadaceae. In the OMZ, major constituents affiliated to the marine SAR11 clade and to thiotrophic gamma-symbionts (25% of all sequences), a group not commonly found in pelagic waters. Sequences affiliating to the phylum Chloroflexi, to the AGG47 and SAR202 clades, to the delta-Proteobacteria, to the Acidobacteria, and to the 'anammox group' of the Planctomycetes were found exclusively in the OMZ. The bacterial richness in the OMZ was higher than in the oxic surface and deeper oxycline, as revealed by rarefaction analysis and the Chao1 richness estimator (surface: 45 +/- 8, deeper oxycline: 76 +/- 26; OMZ (60 m): 97 +/- 33, OMZ (200 m): 109 +/- 31). OMZ bacterial diversity indices (Fisher's: approximately 30 +/- 5, Shannon's: approximately 3.31, inverse Simpson's: approximately 20) were similar to those found in other pelagic marine environments. Thus, our results indicate a distinct and diverse bacterial community within the OMZ, with presumably novel and yet uncultivated bacterial lineages.

The metatranscriptome of a deep-sea hydrothermal plume is dominated by water column methanotrophs and lithotrophs

“…SUP05 is abundant in oxic/anoxic interfacial environments such as deep-sea hydrothermal plumes (Sunamura et al, 2004;Dick and Tebo, 2010;German et al, 2010), oxygen minimum zones (Stevens and Ulloa, 2008;Lavik et al, 2009;Walsh et al, 2009;Canfield et al, 2010) and symbioses with deep-sea bivalves (Newton et al, 2007). Our data set supports previous genomic studies that showed that members of this group are chemolithoautotrophic, obtaining energy by coupling sulfur oxidation to reduction of nitrate and/or oxygen (Newton et al, 2007;Walsh et al, 2009).…”

Inter-comparison of the potentially active prokaryotic communities in the halocline sediments of Mediterranean deep-sea hypersaline basins

“…The Chloroflexi were represented by 38 OTUs, all of them falling in the yet--uncultivated phylogenetic clade SAR202. These Bacteria are common in meso--and bathypelagic ocean waters (Morris et al 2004;Schattenhofer et al 2009) but also in oxygen minimum zones (Stevens & Ulloa 2008). The 30 Gammaproteobacterial OTUs recovered from sediments at the control site were related to known bacterial genera in deep--sea sediments such as Pseudomonas, Pseudolateromonas, Psychrobacter and Aliivibrio.…”

Hydrography shapes bacterial biogeography of the deep Arctic Ocean

“…The most abundant group represented only 10% of the Gammaproteobacteria sequences and belonged to an uncultured cluster, previously named Arctic96BD-19 (Bano and Hollibaugh, 2002) or the GSO cluster (Lavik et al, 2009), containing a chemolithotrophic sulfide-oxidizer bacteria. The second most abundant group of Gammaproteobacteria sequences belonged to the ZD0417 cluster (Stevens and Ulloa, 2008) (Supplementary Figure S6). Other Gammaproteobacteria belonged to orders Oceanospirillales, Alteromonadales and Thiotrichales.…”