Ecological significance of Candidatus ARS69 and Gemmatimonadota in the Arctic glacier foreland ecosystems.

The Gemmatimonadota phylum has been widely detected in diverse natural environments, yet their specific ecological roles in many habitats remain poorly investigated. Similarly, the Candidatus ARS69 phylum has been identified only in a few habitats, and literature on their metabolic functions is relatively scarce. In the present study, we investigated the ecological significance of phyla Ca.

Salinity-controlled distribution of prokaryotic communities in the Arctic sea-ice melt ponds.

The thawing of snow and sea ice produces distinctive melt ponds on the surface of the Arctic sea ice, which covers a significant portion of the surface sea ice during summer. Melt-pond salinity impacts heat transfer to the ice below and the melting rate. It is widely known that melt ponds play a significant role in heat fluxes, ice-albedo feedback, and sea-ice energy balance.

Metagenomic insights into novel microbial lineages with distinct ecological functions in the Arctic glacier foreland ecosystems.

Land-terminating glaciers are retreating globally, resulting in the expansion of the ice-free glacier forelands (GFs). These GFs act as a natural laboratory to study microbial community succession, soil formation, and ecosystem development. Here, we have employed gene-centric and genome-resolved metagenomic approaches to disseminate microbial diversity, community structure, and their associated biogeochemical processes involved in the carbon, nitrogen, and sulfur cycling across three GF ecosystems.

Vertical segregation and phylogenetic characterization of archaea and archaeal ammonia monooxygenase gene in the water column of the western Arctic Ocean.

Archaea constitute a substantial fraction of marine microbial biomass and play critical roles in the biogeochemistry of oceans. However, studies on their distribution and ecology in the Arctic Ocean are relatively scarce. Here, we studied the distributions of archaea and archaeal ammonia monooxygenase (amoA) gene in the western Arctic Ocean, using the amplicon sequencing approach from the sea surface to deep waters up to 3040 m depth.

Stochastic Processes Dominate in the Water Mass-Based Segregation of Diazotrophs in a High Arctic Fjord (Svalbard).

Nitrogen-fixing or diazotrophic microbes fix atmospheric nitrogen (N) to ammonia (NH) using nitrogenase enzyme and play a crucial role in regulating marine primary productivity and carbon dioxide sequestration. However, there is a lack of information about the diversity, structure, and environmental regulations of the diazotrophic communities in the high Arctic fjords, such as Kongsfjorden. Here, we employed nifH gene sequencing to clarify variations in composition, community structure, and assembly mechanism among the diazotrophs of the salinity-driven stratified waters of Kongsfjorden.

Fjords of the western and northern regions of Svalbard harbour distinct bacterioplankton community structures.

Fjords are highly dynamic ecosystems that are known to be sentinels to climate change due to increased glaciomarine interactions. The convergence and mixing of warm Atlantic water (AW) and cold Arctic water (AW) is known to influence the hydrodynamics and ecology of the Arctic fjords. However, most past studies were limited to single-fjord ecosystems, determining the baseline knowledge of inter-fjord comparison on bacterioplankton diversity and distribution patterns.

Production and optimization of l-asparaginase by Streptomyces koyangensis SK4 isolated from Arctic sediment.

Actinomycetes isolated from the Arctic sediment were evaluated for the production of the enzyme l-asparaginase, an enzyme used to treat acute lymphoblastic leukemia. The most potent strain Streptomyces koyangensis SK4 was selected for l-asparaginase enzyme production by submerged fermentation. The effect of various fermentation parameters on enzyme production was analyzed statistically using the Plackett-Burman design and response surface method.

Water Mass Controlled Vertical Stratification of Bacterial and Archaeal Communities in the Western Arctic Ocean During Summer Sea-Ice Melting.

The environmental variations and their interactions with the biosphere are vital in the Arctic Ocean during the summer sea-ice melting period in the current scenario of climate change. Hence, we analysed the vertical distribution of bacterial and archaeal communities in the western Arctic Ocean from sea surface melt-ponds to deep water up to a 3040 m depth. The distribution of microbial communities showed a clear stratification with significant differences among different water depths, and the water masses in the Arctic Ocean - surface mixed layer, Atlantic water mass and deep Arctic water - appeared as a major factor explaining their distribution in the water column.

Microbial diversity and associated metabolic potential in the supraglacial habitat of a fast-retreating glacier: a case study of Patsio glacier, North-western Himalaya.

In the present study, we investigated the microbial community composition and their associated metabolic potentials using the 16S rRNA gene (V3-V4) and ITS (ITS1) amplicon sequencing approach in the Patsio glacier. The bacterial community composition was mainly dominated by Bacteroidota (18%-38% of total reads) and Cyanobacteria (9%-30%), along with a rare Candidate phylum Patescibacteria. Ferruginibacter (13%) and Polaromonas (8%) were the most dominant genera identified across the samples known to have potential ecological roles in colonization, driving the functioning of supraglacial habitats.

Roseitranquillus sediminis gen. nov., sp. nov. a novel genus and species of the family Rhodobacteraceae, isolated from sediment of an Arctic fjord.

A Gram-negative, aerobic, non-motile, oxidase-positive, catalase-positive, rod-shaped bacterium, designated strain MCCB 386 was isolated from sediment samples collected from Kongsfjorden, an Arctic fjord. The strain MCCB 386 showed growth at 4-37 °C (optimum 27°C) in the presence of 1-8% NaCl (w/v, optimum 3.5%) and at pH 6.

Spatially resolved assembly, connectivity and structure of particle-associated and free-living bacterial communities in a high Arctic fjord.

The assembly processes that underlie the composition and connectivity of free-living (FL) and particle-associated (PA) bacterial communities from surface to deep waters remain little understood. Here, using phylogenetic null modeling, we quantify the relative influence of selective and stochastic mechanisms that assemble FL and PA bacterial communities throughout the water column in a high Arctic fjord. We demonstrate that assembly processes acting on FL and PA bacterial communities are similar in surface waters, but become increasingly distinct in deep waters.

Marine Group-II archaea dominate particle-attached as well as free-living archaeal assemblages in the surface waters of Kongsfjorden, Svalbard, Arctic Ocean.

Marine archaea are a significant component of the global oceanic ecosystems, including the polar oceans. However, only a few attempts have been made to study archaea in the high Arctic fjords. Given the importance of Archaea in carbon and nitrogen cycling, it is imperative to explore their diversity and community composition in the high Arctic fjords, such as Kongsfjorden (Svalbard).

Pseudonocardia cytotoxica sp. nov., a novel actinomycete isolated from an Arctic fjord with potential to produce cytotoxic compound.

Herein we report the isolation of a novel actinomycete, strain MCCB 268, from the sediment sample collected from a high Arctic fjord Kongsfjorden. MCCB 268 showed greater than 97% 16S rRNA gene sequence similarity with those of Pseudonocardia konjuensis LM 157 (98.06%), Pseudonocardia soli NW8-21 (97.

Response of bacterial communities from Kongsfjorden (Svalbard, Arctic Ocean) to macroalgal polysaccharide amendments.

Macroalgae are abundant in coastal Arctic habitats and contain a large amount of polysaccharides. Increased macroalgal productivity due to warmer temperatures and reduced sea-ice cover contribute a significant amount of polysaccharide-rich detritus in the region. To study bacterial degradation of macroalgal polysaccharides and their potential impact on biogeochemical processes we studied the response of bacterial communities from Kongsfjorden, Svalbard (Arctic Ocean) to alginate (AL) and agarose (AG) amendments, using an ex-situ microcosm experiment.

Diversity of retrievable heterotrophic bacteria in Kongsfjorden, an Arctic fjord.

The diversity and abundance of retrievable pelagic heterotrophic bacteria in Kongsfjorden, an Arctic fjord, was studied during the summer of 2011 (June, August, and September). Retrievable bacterial load ranged from 10 to 10CFUL in June, while it was 10-10CFUL in August and September. Based on 16S rRNA gene sequence similarities, a higher number of phylotypes was observed during August (22 phylotypes) compared to that during June (6 phylotypes) and September (12 phylotypes).