Biofilm Formation in Dairy: A Food Safety Concern—Insights into the prevalence of Pseudomonadota and yeasts on milking system surface biofilms
Bibliographic record
Abstract
Biofilms pose major challenges to milk quality and safety, yet their composition in the dairy environment remains under-characterized. This study investigated the prevalence and composition of biofilms on milking system surfaces in commercial dairy farms, focusing on Pseudomonadota, a dominant phylum in raw milk. We sampled bulk tank raw milk (BTRM), tap water, and milking equipment surfaces after cleaning from 20 dairy farms in Québec, Canada, using S1 milk agar, specifically designed to target Pseudomonadota through a culturomics approach. A total of 474 colonies were selected and identified by MALDI-TOF MS. Results demonstrated the presence of multispecies biofilms, within the phylum of Pseudomonadota, including potential spoilage and pathogenic bacteria, such as Pseudomonas aeruginosa. Furthermore, the study revealed a significant presence of yeasts (42% of the isolates), predominantly Candida parapsilosis. Biofilms were predominantly detected in milk pipelines and milking machines (milk pipeline: 5.42 log gene copy number/swab; milking machine: 5.16 log gene copy number/swab), with greater bacterial loads quantified by quantitative PCR in fall than spring or summer. Partial least squares discriminant analysis revealed that the microbial composition of biofilms differed from that of BTRM (classification error rate: 0.23 and area under the curve: 0.95), although several species were shared, such as Candida parapsilosis and P. aeruginosa, and Escherichia coli. Tap water was not identified as a major contamination source of Pseudomonadota for dairy biofilms as only 2 species were shared across water, BTRM, and biofilm samples (Pantoea agglomerans and Serratia liquefaciens). The presence of these biofilms, harboring potentially pathogenic and spoilage microorganisms, poses a challenge to milk quality and safety. These findings provide data on the diversity of culturable Pseudomonadota and yeasts in biofilms on dairy farms and highlight the need for improved sanitation practices to mitigate microbial contamination in milk production.
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 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) | 0.000 | 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 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".