The Bovine Ocular Microbiome: A Multi-Approach Study of Composition and Antimicrobial Activity
Bibliographic record
Abstract
BACKGROUND: Despite widespread use of antimicrobials and vaccines, the incidence of infectious bovine keratoconjunctivitis (IBK), or pinkeye, continues to increase in North American beef cow-calf operations. Recent research suggests that there is potential for the commensal ocular microbiome to help mitigate IBK. Therefore, this study characterized the ocular microbiome of cattle with and without IBK using culture-based methods and shotgun metagenomic sequencing and assessed the ability of commensal bacteria to inhibit Moraxella spp. in vitro. Ocular swabs (n = 143) were collected from IBK-affected (n = 102) and healthy cattle (n = 41) before antimicrobial treatment from North Dakota herds. Bacteria were cultured aerobically and anaerobically on five different media and the isolates were identified. A subset of swabs (37 IBK-affected; 12 healthy) underwent shotgun metagenomic sequencing. The genomes of 31 isolates, including Moraxella bovoculi, Moraxella bovis, and commensal bacteria, were also sequenced. Fifty-two commensal isolates were screened for inhibition of Moraxella spp. using an agar slab method, with five isolates further tested by qPCR for inhibition in the presence of the culturable ocular microbiome. RESULTS: The 351 bacterial isolates taxonomically identified represented 61 genera from three phyla. The majority of isolates belonged to Bacillus (25.9%), Streptococcus (11.1%), Staphylococcus (10.1%), and Moraxella (9.4%) genera. Shotgun metagenomic analysis revealed significant differences in ocular microbial species composition between IBK-affected and healthy cattle (R² = 0.05; P = 0.015) based on Bray-Curtis dissimilarity. Dominant bacterial species included Cutibacterium acnes, Mannheimia pernigra, Mesomycoplasma bovoculi, Moraxella bovis, and Moraxella bovoculi. Eight bacterial species, including Bifidobacterium globosum and Bacillus licheniformis, were more abundant in healthy cattle, while Arthrobacter luteus was enriched in IBK cases. Thirty-seven high-quality metagenome-assembled genomes were also recovered, with 27% classified as Mesomycoplasma bovoculi. Moraxella spp. genomes exhibited strain-specific antimicrobial resistance and virulence gene diversity. Seventeen commensal isolates inhibited Moraxella, with Weizmannia coagulans, Lentilactobacillus buchneri, and Paenibacillus polymyxa showing strong activity. Selected isolates maintained inhibitory effects in co-culture with the ocular microbiome. CONCLUSION: The ocular surface of beef cattle is inhabited by a diverse microbiome that includes several bacterial strains that have the potential to be used as therapeutics to inhibit IBK pathogens.
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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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 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 | 0.001 |
| Research integrity | 0.001 | 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".