Comparative biodegradation analysis of three compostable polyesters by a marine microbial community.

Biodegradable plastics can be used in applications where the end product cannot be efficiently recycled due to high levels of contaminations, e.g., food or soil.

Global diversity and inferred ecophysiology of microorganisms with the potential for dissimilatory sulfate/sulfite reduction.

Sulfate/sulfite-reducing microorganisms (SRM) are ubiquitous in nature, driving the global sulfur cycle. A hallmark of SRM is the dissimilatory sulfite reductase encoded by the genes dsrAB. Based on analysis of 950 mainly metagenome-derived dsrAB-carrying genomes, we redefine the global diversity of microorganisms with the potential for dissimilatory sulfate/sulfite reduction and uncover genetic repertoires that challenge earlier generalizations regarding their mode of energy metabolism.

Postglacial adaptations enabled colonization and quasi-clonal dispersal of ammonia-oxidizing archaea in modern European large lakes.

Ammonia-oxidizing archaea (AOA) play a key role in the aquatic nitrogen cycle. Their genetic diversity is viewed as the outcome of evolutionary processes that shaped ancestral transition from terrestrial to marine habitats. However, current genome-wide insights into AOA evolution rarely consider brackish and freshwater representatives or provide their divergence timeline in lacustrine systems.

High-Frequency Variability of Bacterioplankton in Response to Environmental Drivers in Red Sea Coastal Waters.

Autotrophic and heterotrophic bacterioplankton are essential to the biogeochemistry of tropical ecosystems. However, the processes that govern their dynamics are not well known. We provide here a high-frequency assessment of bacterial community dynamics and concurrent environmental factors in Red Sea coastal waters.

Quantification of archaea-driven freshwater nitrification from single cell to ecosystem levels.

Deep oligotrophic lakes sustain large populations of the class Nitrososphaeria (Thaumarchaeota) in their hypolimnion. They are thought to be the key ammonia oxidizers in this habitat, but their impact on N-cycling in lakes has rarely been quantified. We followed this archaeal population in one of Europe's largest lakes, Lake Constance, for two consecutive years using metagenomics and metatranscriptomics combined with stable isotope-based activity measurements.

KAUST Metagenomic Analysis Platform (KMAP), enabling access to massive analytics of re-annotated metagenomic data.

Exponential rise of metagenomics sequencing is delivering massive functional environmental genomics data. However, this also generates a procedural bottleneck for on-going re-analysis as reference databases grow and methods improve, and analyses need be updated for consistency, which require acceess to increasingly demanding bioinformatic and computational resources. Here, we present the KAUST Metagenomic Analysis Platform (KMAP), a new integrated open web-based tool for the comprehensive exploration of shotgun metagenomic data.

Fine-scale metabolic discontinuity in a stratified prokaryote microbiome of a Red Sea deep halocline.

Deep-sea hypersaline anoxic basins are polyextreme environments in the ocean's interior characterized by the high density of brines that prevents mixing with the overlaying seawater, generating sharp chemoclines and redoxclines up to tens of meters thick that host a high concentration of microbial communities. Yet, a fundamental understanding of how such pycnoclines shape microbial life and the associated biogeochemical processes at a fine scale, remains elusive. Here, we applied high-precision sampling of the brine-seawater transition interface in the Suakin Deep, located at 2770 m in the central Red Sea, to reveal previously undocumented fine-scale community structuring and succession of metabolic groups along a salinity gradient only 1 m thick.

Desulfolutivibrio sulfoxidireducens gen. nov., sp. nov., isolated from a pyrite-forming enrichment culture and reclassification of Desulfovibrio sulfodismutans as Desulfolutivibrio sulfodismutans comb. nov.

Two strains of sulfate-reducing bacteria (J.5.4.

Microbial ecology of deep-sea hypersaline anoxic basins.

Deep hypersaline anoxic basins (DHABs) are unique water bodies occurring within fractures at the bottom of the sea, where the dissolution of anciently buried evaporites created dense anoxic brines that are separated by a chemocline/pycnocline from the overlying oxygenated deep-seawater column. DHABs have been described in the Gulf of Mexico, the Mediterranean Sea, the Black Sea and the Red Sea. They are characterized by prolonged historical separation of the brines from the upper water column due to lack of mixing and by extreme conditions of salinity, anoxia, and relatively high hydrostatic pressure and temperatures.

Genomes of rumen bacteria encode atypical pathways for fermenting hexoses to short-chain fatty acids.

Bacteria have been thought to follow only a few well-recognized biochemical pathways when fermenting glucose or other hexoses. These pathways have been chiseled in the stone of textbooks for decades, with most sources rendering them as they appear in the classic 1986 text by Gottschalk. Still, it is unclear how broadly these pathways apply, given that they were established and delineated biochemically with only a few model organisms.

Genomic diversification of giant enteric symbionts reflects host dietary lifestyles.

Herbivorous surgeonfishes are an ecologically successful group of reef fish that rely on marine algae as their principal food source. Here, we elucidated the significance of giant enteric symbionts colonizing these fishes regarding their roles in the digestive processes of hosts feeding predominantly on polysiphonous red algae and brown algae, which contain different polysaccharide constituents. Using metagenomics, single-cell genomics, and metatranscriptomic analyses, we provide evidence of metabolic diversification of enteric microbiota involved in the degradation of algal biomass in these fishes.

Genomic characterization of two novel SAR11 isolates from the Red Sea, including the first strain of the SAR11 Ib clade.

The SAR11 clade (Pelagibacterales) is a diverse group that forms a monophyletic clade within the Alphaproteobacteria, and constitutes up to one third of all prokaryotic cells in the photic zone of most oceans. Pelagibacterales are very abundant in the warm and highly saline surface waters of the Red Sea, raising the question of adaptive traits of SAR11 populations in this water body and warmer oceans through the world. In this study, two pure cultures were successfully obtained from surface waters on the Red Sea: one isolate of subgroup Ia and one of the previously uncultured SAR11 Ib lineage.

Metabolic traits of an uncultured archaeal lineage--MSBL1--from brine pools of the Red Sea.

The candidate Division MSBL1 (Mediterranean Sea Brine Lakes 1) comprises a monophyletic group of uncultured archaea found in different hypersaline environments. Previous studies propose methanogenesis as the main metabolism. Here, we describe a metabolic reconstruction of MSBL1 based on 32 single-cell amplified genomes from Brine Pools of the Red Sea (Atlantis II, Discovery, Nereus, Erba and Kebrit).

Diversification and niche adaptations of Nitrospina-like bacteria in the polyextreme interfaces of Red Sea brines.

Nitrite-oxidizing bacteria (NOB) of the genus Nitrospina have exclusively been found in marine environments. In the brine-seawater interface layer of Atlantis II Deep (Red Sea), Nitrospina-like bacteria constitute up to one-third of the bacterial 16S ribosomal RNA (rRNA) gene sequences. This is much higher compared with that reported in other marine habitats (~10% of all bacteria), and was unexpected because no NOB culture has been observed to grow above 4.

Comprehensive Genomic Analyses of the OM43 Clade, Including a Novel Species from the Red Sea, Indicate Ecotype Differentiation among Marine Methylotrophs.

The OM43 clade within the family Methylophilaceae of Betaproteobacteria represents a group of methylotrophs that play important roles in the metabolism of C1 compounds in marine environments and other aquatic environments around the globe. Using dilution-to-extinction cultivation techniques, we successfully isolated a novel species of this clade (here designated MBRS-H7) from the ultraoligotrophic open ocean waters of the central Red Sea. Phylogenomic analyses indicate that MBRS-H7 is a novel species that forms a distinct cluster together with isolate KB13 from Hawaii (Hawaii-Red Sea [H-RS] cluster) that is separate from the cluster represented by strain HTCC2181 (from the Oregon coast).

Diet strongly influences the gut microbiota of surgeonfishes.

Intestinal tracts are among the most densely populated microbial ecosystems. Gut microbiota and their influence on the host have been well characterized in terrestrial vertebrates but much less so in fish. This is especially true for coral reef fishes, which are among the most abundant groups of vertebrates on earth.

Comparative genomics reveals adaptations of a halotolerant thaumarchaeon in the interfaces of brine pools in the Red Sea.

The bottom of the Red Sea harbors over 25 deep hypersaline anoxic basins that are geochemically distinct and characterized by vertical gradients of extreme physicochemical conditions. Because of strong changes in density, particulate and microbial debris get entrapped in the brine-seawater interface (BSI), resulting in increased dissolved organic carbon, reduced dissolved oxygen toward the brines and enhanced microbial activities in the BSI. These features coupled with the deep-sea prevalence of ammonia-oxidizing archaea (AOA) in the global ocean make the BSI a suitable environment for studying the osmotic adaptations and ecology of these important players in the marine nitrogen cycle.

Diversity of picoeukaryotes at an oligotrophic site off the Northeastern Red Sea Coast.

Background: Picoeukaryotes are protists ≤ 3 μm composed of a wide diversity of taxonomic groups. They are an important constituent of the ocean's microbiota and perform essential ecological roles in marine nutrient and carbon cycles. Despite their importance, the true extent of their diversity has only recently been uncovered by molecular surveys that resulted in the discovery of a substantial number of previously unknown groups.

Combined analyses of the ITS loci and the corresponding 16S rRNA genes reveal high micro- and macrodiversity of SAR11 populations in the Red Sea.

Bacteria belonging to the SAR11 clade are among the most abundant prokaryotes in the pelagic zone of the ocean. 16S rRNA gene-based analyses indicate that they constitute up to 60% of the bacterioplankton community in the surface waters of the Red Sea. This extremely oligotrophic water body is further characterized by an epipelagic zone, which has a temperature above 24 °C throughout the year, and a remarkable uniform temperature (~22 °C) and salinity (~41 psu) from the mixed layer (~200 m) to the bottom at over 2000 m depth.

Biogeography of pelagic bacterioplankton across an antagonistic temperature-salinity gradient in the Red Sea.

The Red Sea is a unique marine ecosystem with contrasting gradients of temperature and salinity along its north-to-south axis. It is an extremely oligotrophic environment that is characterized by perpetual year-round water column stratification, high annual solar irradiation, and negligible riverine and precipitation inputs. In this study, we investigated whether the contemporary environmental conditions shape community assemblages by pyrosequencing 16S rRNA genes of bacteria in surface water samples collected from the northeastern half of this water body.

Nitrate reduction, nitrous oxide formation, and anaerobic ammonia oxidation to nitrite in the gut of soil-feeding termites (Cubitermes and Ophiotermes spp.).

Soil-feeding termites play important roles in the dynamics of carbon and nitrogen in tropical soils. Through the mineralization of nitrogenous humus components, their intestinal tracts accumulate enormous amounts of ammonia, and nitrate and nitrite concentrations are several orders of magnitude above those in the ingested soil. Here, we studied the metabolism of nitrate in the different gut compartments of two Cubitermes and one Ophiotermes species using (15)N isotope tracer analysis.

Microbiology of the Red Sea (and other) deep-sea anoxic brine lakes.

The Red Sea harbours approximately 25 deep-sea anoxic brine pools. They constitute extremely unique and complex habitats with the conjugation of several extreme physicochemical parameters rendering them some of the most inhospitable environments on Earth. After 50 years of research mostly driven by chemists, geophysicists and geologists, the microbiology of the brines has been receiving increased interest in the last decade.

Benzoic acid-degrading bacteria from the intestinal tract of Macrotermes michaelseni Sjöstedt.

The intestinal tracts of termites host a wide variety of microbial symbionts, which have been implicated in degradative processes. In this study, a fungus-cultivating termite, Macrotermes michaelseni was found to harbor 2.2 x 10(6) bacterial cells per ml of gut homogenates capable of degrading benzoic acid.