Microbial diversity, activity, and ecology of a hypersaline high Arctic spring system
Bibliographic record
Abstract
The Lost Hammer (LH) spring, located on Axel Heiberg Island in the Canadian High Arctic, is the coldest and saltiest terrestrial spring discovered to date. It is characterized by perennial discharges of subzero temperatures (-5°C), hypersalinity (24% salinity), along with reducing (≈-165 mV), microoxic, and oligotrophic conditions. It is rich in sulfates (10.0% w/w), dissolved H2S/sulfides (up to 25 ppm), ammonia (≈381 μM), and methane (11.1 g d-1). The LH spring system contains the outlet and the outflow channel. In the initial study of the LH channel sediment, the results determined the microbial abundance by using fluorescent microscopy in the channel sediment; also, the study characterized the cultured representatives and confirmed that most of these isolates are halotolerant and psychrotolerant microorganisms. The mineralization assays on the LH channel sediment revealed that the heterotrophic microorganisms remained activity down to -20°C. To determine the total microbial communities inhabiting the LH spring system, the study demonstrated the microbial 16S rRNA genes and the active 16S rDNA profiles for different sampling locations, including the outlet, channel and the adjacent tundra. We identified that the Bacteria from the five phyla (Bacteroidetes, Proteobacteria, Actinobacteria, Firmicutes, and Cyanobacteria) were the dominant bacterial groups at the LH spring system. In the archaeal communities, microorganisms affiliated with three phyla (Euryarchaeota, Crenarchaeota, and Thaumarchaeota) were identified. To determine its total functional and genetic potential, we performed metagenomic analysis of the LH spring outlet microbial community. Reconstruction of the enzyme pathways responsible for bacterial nitrification/denitrification/ammonification and sulfate reduction appeared nearly complete in the metagenomic dataset. Stress-response genes for adapting to cold, osmotic stress, and oxidative stress were also abundant in the metagenome. Comparing functional community composition of the LH spring to metagenomes from other saline/subzero environments revealed a close association between LH and another Canadian High Arctic permafrost environment, particularly in genes related to sulfur metabolism and dormancy. To identify the abundance and the presence of the featured genes (amoA and hcd) of Thaumarchaea at the LH spring system, we performed qPCR to assess their abundance. A phylogenetic analysis was performed using the putative amino acid sequences of these genes to identify their phylogenetic affiliation. The copy numbers of Thaumarchaeal amoA and hcd genes in LH channel sediment and the adjacent tundra were roughly 10 to a hundred-folds less than those reported in other environments. The phylogenetic tree of amoA showed similar patterns of grouping as the analysis done by 16S rRNA. This thesis demonstrates the microbial ecology, diversity and activity at the LH spring system and provides knowledge for the microbiology studies on cryo- and hypersaline environments.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".