Lactic acid bacteria and spoilage bacteria: Their interactions in <i>Escherichia coli</i><scp>O157</scp>:<scp>H7</scp> biofilms on food contact surfaces and implications for beef contamination
Why this work is in the frame
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Bibliographic record
Abstract
Abstract This research explores the interaction between Shiga toxin‐producing Escherichia coli (STEC) O157:H7 and bacteria species commonly found in beef processing environments, specifically Carnobacterium , Lactobacillus , Comamonas , Raoultella , and Pseudomonas . The study investigated how various environmental conditions impact the formation of biofilms and the ability of O157:H7 to transfer from multispecies biofilm onto beef surfaces. For this purpose, a mixture of lactic acid bacteria (LAB), spoilage bacteria (10 6 CFU/mL), and E. coli O157 (10 3 CFU/mL) were combined as follows: LAB ( T1) : Carnobacterium piscicola + Lactobacillus bulgaricus + O157:H7, an spoilage bacteria ( T2) : Comamonas koreensis + Raoultella terrigena + O157:H7 , an spoilage bacteria ( T3) : Pseudomonas aeruginosa + C. koreensis strain + O157:H7 and only O157:H7 as control ( T4 ). Multispecies biofilms were developed on thermoplastic polyurethane (TPU) and stainless steel (SS) coupons at 10 and 25°C for 6 days, washed and stored for 6, 30, and 60 days at wet (60%–90% RH) and dry (20%–50%, RH) conditions. To evaluate O157:H7 transfer, beef cubes (3 × 3 × 1 cm) were placed on the coupons, followed by a 50‐g weight (7.35 kPa). The experiment was repeated three times in triplicate for each strain combination. Results demonstrate that biofilms formed at 10°C were generally weaker (less biomass) than those at 25°C. Regardless of temperature, more viable O157:H7 cells were transferred to beef from moist biofilms on TPU surfaces. At 25°C, T3 biofilm exhibited the lowest O157:H7 transfer to beef by 1.44 log 10 CFU/cm 2 ( p < 0.01). At 10°C, none of the multispecies biofilm (T1–T3) affected the number of O157:H7 transfers to beef ( p > 0.05). Notably, O157:H7 was not detected on food contact surfaces with 30 and 60‐day‐old dry biofilms (T1–T4). Through enrichment, E. coli O157:H7 was recovered from multispecies biofilms T1, T2, and T3. Findings from this study imply that multispecies biofilms contribute to the persistence of O157:H7 under dry conditions, regardless of temperature. These results underscore the intricate influence of multiple environmental factors—including surface type, biofilm age, humidity, temperature, and the presence of other bacterial species—on the risk of beef contamination facilitated by biofilms.
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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 | 0.001 | 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 it