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Yogurts were prepared by using yogurt cultures combined to mixed cultures of bifidobacteria (Bifidobacterium animalis, Bifidobacterium bifidum, Bifidobacterium breve, Bifidobacterium infantis, and Bifidobacterium longum) and by adding a preincubation step (1.5 h at 50 degrees C) with bifidobacteria to the conventional method of manufacture in order to produce oligosaccharides. The survival of bifidobacteria was drastically affected during storage of yogurts, except for products containing B. animalis, in which viable counts remained at >10(6) cfu/g after 28 d of storage at 4 degrees C. Oligosaccharides with a degree of polymerization of 3 were produced during the preincubation step (0.31 to 0.68%), and the amount in the final products varied according to the species of bifidobacteria inoculated during the preincubation step or the concentration of bifidobacteria used as second inoculum during the fermentation process. In fact, the higher concentration of oligosaccharides measured at the end of the fermentation process (0.72%) and the 28 d-storage period (0.67%) was obtained for yogurts containing B. infantis. However, yogurts containing B. breve showed higher beta-galactosidase activities and had lower lactose concentrations after the fermentation process and the storage period than the other yogurts. The use of a mixed cultures of bifidobacteria (B. animalis, B. infantis, or B. breve) thus allows the production of yogurts in which bifidobacteria can survive in relatively high cell numbers and contain appreciable amount of oligosaccharides.

Tracking sources of contamination is an issue related to food safety. In a preliminary study conducted to evaluate the distribution of thermophilic Campylobacter in the environment surrounding dairy cattle and swine production, a number of Campylobacter lanienae were directly detected by PCR. The amplicons came from dairy cows and pig fecal samples, as well as from stored manure. DNA sequencing of a 360-bp fragment of C. lanienae 16S rRNA gene was performed. Alignment of sequences confirmed the bacterial identification as sequences shared 99-100% homology with C. lanienae 16S rRNA gene sequences available in GenBank. Interestingly, bioinformatics analyses also revealed two different genetic clusters depending on the animal reservoir. More samples and other molecular techniques need to be tested in order to characterize and evaluate the distribution of this microorganism in the agri-food chain.

Dairy cattle are considered a Campylobacter reservoir in the epidemiology of campylobacteriosis. Currently, very little data on the prevalence of Campylobacter in dairy herds are available in the Province of Quebec, Canada. The objectives of this study were to evaluate the prevalence of Campylobacter associated with management practices in 40 dairy cattle herds as well as to characterize the bacterial genetic diversity. Fecal samples from 797 lactating cows of 40 dairy farms, water provided to animals, milk from bulk tank, and fecal matters from pens were analyzed for the presence of Campylobacter. Management information was collected using a short survey and the geographical positioning was mapped for each farm. Bacterial genetic characterization was performed by pulsed-field gel electrophoresis and flaA-typing. In total, 29 farms (72.5%) were found positive for Campylobacter spp. and 20 (50%) of them were positive for Campylobacter jejuni. In animals, 27.6% of the fecal samples were positive for Campylobacter spp. C. hyointestinalis was the most prevalent species (19.3%) in herds, followed by C. jejuni (6.5%). No Campylobacter were recovered from water or milk samples. Component-fed ration systems and the lack of biosecurity measures were associated with an increased prevalence of C. jejuni on the studied farms. Campylobacter-positive farms were scattered throughout the region, and bacterial genetic heterogeneity was observed between farms and inside the herds. This study is the first one to characterize C. jejuni isolates from dairy herds in the Province of Quebec. These observations may be useful in order to elaborate risk-mitigation strategies.

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Irrigation water has been identified as a possible source of vegetable contamination by foodborne pathogens. Risk management for pathogens such as Campylobacter spp. and Listeria monocytogenes in fields can be influenced by the source of the irrigation water and the time interval between last irrigation and harvest. Plots of romaine lettuce were irrigated with manure-contaminated water or aerated pond water 21, 7, or 3 days prior to harvesting, and water and muck soil samples were collected at each irrigation treatment. Lettuce samples were collected at the end of the trials. The samples were tested for the presence of Campylobacter spp. and L. monocytogenes. Campylobacter coli was isolated from 33% of hog manure samples (n = 9) and from 11% of the contaminated water samples (n = 27), but no lettuce samples were positive (n = 288). L. monocytogenes was not found in manure, and only one sample of manure-contaminated irrigation water (n = 27) and one lettuce sample (n = 288) were positive. No Campylobacter or L. monocytogenes was recovered from the soil samples (n = 288). Because of the low incidence of pathogens, it was not possible to link the contamination of either soil or lettuce with the type of irrigation water. Nevertheless, experimental field trials mimicking real conditions provide new insights into the survival of two significant foodborne pathogens on romaine lettuce.

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