Cold adapted desiccation-tolerant bacteria isolated from polar soils presenting high resistance to anhydrobiosis
Bibliographic record
Abstract
Abstract Life on Earth is strictly dependent on liquid water. In polar terrestrial environments, water exists in solid state during almost the entire year. Polar microorganisms have not only to adjust their metabolism to survive at subzero temperatures, but also need to cope with extremely dry conditions. We investigated the presence of desiccation-adapted bacteria in Arctic permafrost and Antarctic surface soils and characterized their survivability to dryness. We selected desiccation tolerant cells by treating the soils with chloroform prior to cultivation, in order to mimic the stress of low water activity for long periods. From over 1000 colonies from different samples, 23 unique strains were selected and identified as members of phyla Firmicutes, Proteobacteria and Actinobacteria . About 60% of the strains survived after 50 days in anhydrobiosis. The competence to withstand desiccation varied between close related strains isolated from different locations, bringing the question if environmental conditions may play a role in the observed desiccation tolerance. Survivability was also affected by the solution in which the cells were suspended before drying; R2B medium being more protective than water. This is the first time that chloroform was used to select desiccation tolerant microorganisms from polar soils. The collection of polar microorganisms described herein opens the possibility of further experiments aiming to investigate the resistance mechanisms of polar anhydrobionts. Desiccation tolerance is fundamental to the survivability of microorganisms to the space environment and at the surface of thin-atmosphere planets like Mars. Therefore, the selected strains may open a road to better understand the limits of cold adapted life on Earth and beyond, and compare mechanisms of resistance with anhydrobionts from divergent extreme 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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 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) | 0.001 | 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".