Salt Tolerance and UV Protection of <i>Bacillus subtilis</i> and <i>Enterococcus faecalis</i> under Simulated Martian Conditions
Bibliographic record
Abstract
Ultraviolet (UV) irradiation on the surface of Mars is an important factor that affects the survivability of microorganisms on Mars. The possibility of martian brines made from Fe 2 (SO 4 ) 3 , MnSO 4 , and MgSO 4 salts providing a habitable niche on Mars via attenuation of UV radiation was investigated on the bacteria Bacillus subtilis and Enterococcus faecalis . Results demonstrate that it is possible for brines containing Fe 2 (SO 4 ) 3 on Mars to provide protection from harmful UV irradiation, even at concentrations as low as 0.5%. Brines made from MnSO 4 and MgSO 4 did not provide significant UV protection, and most spores/cells died over the course of short-term experiments. However, Fe 2 (SO 4 ) 3 brines are strongly acidic and thus were lethal to E. faecalis, when cells were exposed for 7 days. In contrast, B. subtilis, a spore-forming bacterium resistant to pH extremes, was unaffected by the acidic conditions of the brines and did not experience any significant lethal effects in Fe 2 (SO 4 ) 3 . Any extant microbial life in martian Fe 2 (SO 4 ) 3 brines (if present) would need to be capable of surviving acidic environments, if these brines are to be considered a possible habitable niche. The results from this work are important to the search for life on planets with atmospheres that do not significantly attenuate UV radiation ( i.e., like Mars) and to planetary protection, since it is possible that terrestrial bacteria in the genus Bacillus are likely to survive in Fe-sulfate brines on Mars.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 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 teacher head, 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".