Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
2438873 | Journal of Dairy Science | 2013 | 10 Pages |
Abstract
The microbial composition of raw and pasteurized milk is assessed on a daily basis. However, many such tests are culture-dependent, and, thus, bacteria that are present at subdominant levels, or that cannot be easily grown in the laboratory, may be overlooked. To address this potential bias, we have used several culture-independent techniques, including flow cytometry, real-time quantitative PCR, and high-throughput DNA sequencing, to assess the microbial population of milk from a selection of commercial milk producers, pre- and postpasteurization. The combination of techniques employed reveals the presence of a previously unrecognized and diverse bacterial population in unpasteurized cow milk. Most notably, the use of high-throughput DNA sequencing resulted in several bacterial genera being identified in milk samples for the first time. These included Bacteroides, Faecalibacterium, Prevotella, and Catenibacterium. Our culture-independent analyses also indicate that the bacterial population of pasteurized milk is more diverse than previously appreciated, and that nonthermoduric bacteria within these populations are likely to be in a damaged, nonculturable form. It is thus apparent that the application of state-of-the-art approaches can provide a detailed insight into the bacterial composition of milk and could potentially be employed in the future to investigate the factors that influence the composition of these populations.
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Authors
Lisa Quigley, Robert McCarthy, Orla O'Sullivan, Tom P. Beresford, Gerald F. Fitzgerald, R. Paul Ross, Catherine Stanton, Paul D. Cotter,