Investigating the Antimicrobial Potential of Cultivable High Arctic Bacteria
Bibliographic record
Abstract
Antimicrobial resistance (AMR) is one of the most pressing healthcare and environmental challenges of the 21st century. In agricultural settings, the increased prevalence of resistant pathogens infecting livestock are being transmitted to humans and spreading through the food chain causing foodborne illness, while resistant phytopathogens are causing crop losses worldwide. Within this framework, the goal of this doctoral project was to isolate, screen, characterize, and apply cultivable Arctic bacteria exhibiting antimicrobial functions. The first part of this project involved employing two cultivation approaches to isolate and subsequently screen bacterial isolates derived from Canadian high Arctic habitats for antibacterial activities. The first approach included engineering and deploying an in situ cultivation device - the cryo-iplate. The second involved crowdsourcing standard bulk soil plating of twelve different Arctic sample types to a cohort of undergraduate researchers. Through these culturing approaches, bacterial isolates pertaining to Pseudomonas and Paenibacillus spp. exhibiting antibacterial activity against clinically relevant pathogens including methicillin resistant and susceptible Staphylococcus aureus (MRSA and MSSA), Listeria monocytogenes, Salmonella enterica Escherichia coli O157:H7, Acinetobacter baumanii, Enterococcus faecium, and Enterococcus faecalis were identified. Given that these isolates were cultured from a diverse set of Arctic habitats spanning permafrost, saline spring sediments, and cryptoendoliths, our findings suggest that high Arctic environments could potentially represent an untapped reservoir for novel antibacterial metabolites.Since resistant fungal pathogens are increasingly playing a role in the global AMR crisis, the second part of this doctoral project was to characterize the antifungal properties of a putatively novel Arctic species, Pseudomonas sp. B1.1W. This isolate was initially cultured using the cryo-iplate within an active layer permafrost site on Gypsum Hill located at Expedition Fjord, Axel Heiberg Island, Nunavut, Canada and was found to inhibit the growth of the second most prevalent phytopathogenic mold species, Botrytis cinerea, responsible for global crop losses. By mining its genome for antimicrobial BGCs and by biochemically analyzing organic extracts derived from liquid culture supernatants, this B1.1W was found to produce an antifungal molecule part of the viscosin group.The final component of this doctoral project evaluated B1.1W as a potential biocontrol agent against B. cinerea in Cannabis sativa. Cellular inoculants and bioactive extracts prepared from liquid culture supernatants of B1.1W were tested as foliar biocontrol treatments on C. sativa challenged with B. cinerea. Cannabis leaves that were treated with cellular inoculants and organic extracts of B1.1W challenged with B. cinerea featured 43.79% and 89.83% (respectively) less total mold cells. Furthermore, whole cannabis plants that received B1.1W treatments displayed fewer counts of symptomatic foliage throughout the course of a 14-day observation period post B. cinerea challenge compared to untreated controls. Targeted 16S amplicon sequencing of C. sativa leaves treated with cellular inoculants revealed that B1.1W dominates the foliar bacterial community, suggesting that it colonized leaf tissue. By evaluating its antifungal effect in planta and its potential to colonize leaf tissue, B1.1W exhibited biocontrol potential against B.cinerea in cannabis. The studies presented in this thesis ultimately demonstrate how high Arctic bacteria represent a source of potentially novel antimicrobial specialized metabolites with biotechnological applicability
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| 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".