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Foodborne pathogens, including enterohemorrhagic Escherichia coli (EHEC) O157:H7, may enter from the farm environment and foods via several different vectors and influence human health. Here, we employed Caenorhabditis elegans as a host model system and compared specific host responses during EHEC O157:H7 infection using whole-transcriptome analysis. To elucidate the immune pathways stimulated by EHEC O157:H7, we employed quantitative real-time polymerase chain reaction (qRT-PCR), transgenic worms, and RNAi. Whole-transcriptome analysis revealed that genes encoding the cytochrome P450 (CYP450) family were induced more than 10-fold during EHEC O157:H7 infection in C. elegans host models. Importantly, C. elegans mutants lacking CYP450 genes were highly susceptible to EHEC O157:H7 infection compared with wild-type N2 worms. Consistent with susceptibility tests, qRT-PCR results indicated that CYP450 loss-of-function mutations significantly affected the transcriptional induction of antimicrobial peptide genes, such as clec-60. Together, our results provide critical insights into host strategies for avoiding EHEC O157:H7 pathogenesis in the gastrointestinal tract via the cytochrome P450 family and highlights potential molecular targets for preventing the virulence of EHEC O157:H7 in foods.

Bovine milk is highly nutritious, so it creates an ideal environment for the growth of microorganisms. Contamination of milk with microorganisms contributes to overall bacterial composition and has a great influence on the acidification and deterioration of milk. As dairy production and consumption have increased over the past decade, the microbial composition of milk has gained attention. In Korea, milk and milk products are rapidly gaining popularity, but studies of the bacterial composition in milk from Korean farms are limited. In the present study, we performed metagenomic analysis with high-throughput sequencing of DNA to identify bacteria in raw milk collected from 40 dairy farms in 4 different provinces in Korea: Gyeonggi-do, Chungcheong-do, Jeolla-do, and Gyeongsang-do. Representative milk bacterial communities including Proteobacteria, Firmicutes, Bacteroidetes, and Actinobacteria formed the core milk microbiota at the phylum level, and Pseudomonas was found to have the greatest provincial variation at the genus level. In addition, we determined the prevalence of spore-forming bacteria using two independent methods of culturomic analysis by MALDI-TOF and next generation sequencing of 16S rRNA genes, and Bacillus thermoamylovorans was identified to account for the largest proportion. We further confirmed that B. thermoamylovorans was able to survive in dairy products and potentially toxigenic using lab cheese model study and Caenorhabditis elegans as a simple host model. Our result clearly shows that specific provinces have distinct proportions of bacteria that may cause spoilage, suggesting specified farm environment management practices depending on the region. These findings can help Korean dairy farms produce safe, high-quality dairy products and develop new sanitation procedures as well as processing controls.