Inactivation of Group I and Group II Clostridium botulinum spores by ultraviolet irradiation in water
Bibliographic record
Abstract
Spores of Clostridium botulinum are widely distributed in the environment, including in foods. Prevention of foodborne botulism relies on the inhibition of spore germination and subsequent growth and toxin production, or the destruction of viable spores in food and beverages. This study examined the lethality of 254 nm UV radiation (UV-C) to spores of Group I and Group II C. botulinum. Spores of C. botulinum were inactivated by UV-C, with doses required for incremental log reduction (D10) values calculated using linear regression ranging from 2.87 to 3.70 mJ/cm2 for Group I strains and 4.46 to 6.15 mJ/cm2 for Group II strains. The measured D10 value for spores of C. sporogenes ATCC 19404 was 8.27 mJ/cm2 indicating it was more resistant than the strains of C. botulinum used in this study. Calculation of dose per log using a Weibull model resulted in higher D10 values of 6.67 to 8.81 mJ/cm2 for Group I strains and 9.24 to 10.7 mJ/cm2 for Group II strains. Spores of C. sporogenes possessed a D10 value of 14.4 mJ/cm2. The higher values for the Weibull model indicate the Weibull model to be more conservative as a result as it factors in the lag prior to inactivation and the tailing observed with very low numbers of survivors. Spores of both Group I and Group II C. botulinum strains tended to form large aggregates, visible with phase contrast microscopy, that resulted in severe tailing. Disruption of aggregates by ultrasonication was necessary to obtain linear destruction curves extending beyond 5 log reduction. All strains from Group I and Group II required <55 mJ/cm2 to achieve 5 log inactivation. The strain of C. sporogenes used in this work can therefore be a conservative non-pathogenic surrogate, having higher UV-C resistance than the C. botulinum strains used in this study. Overall, this study is the first detailed study to demonstrate UV-C as an effective treatment method to inactivate C. botulinum spores in a suspending medium. In addition, the study paves the way for further studies towards the applications of this technology to inactivate C. botulinum spores in beverages or other liquids.
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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".