Detection and quantification of dairy bacteriophages.

BINETTI, ANA G

Bacteriophages in dairy processing.

Nova Science Publishers

Lugar: New York; Año: 2011; p. 35 - 50

Phage monitoring is critically important for dairy industry, because it is a symptom of the degree of phage accumulation in the plant, and allows to take rapid decisions when an infection episode occurs. Standard microbiological methods (double layer agar test, spot test, sensitivity test, etc.), based on the lysis of sensitive strains in agar layers or liquid media are still being recommended in some standardized protocols for bacteriophage detection. However, these methods require the availability of a sensitive strain and are time-consuming (at least, 24 h), which sometimes is crucial for the prevention of the lysis of the whole bacterial culture. Nevertheless, since they are relatively simple to implement and do not require special equipments, they are even nowadays used to detection and quantification of dairy phages for routine controls in dairy plant laboratories. During the last 15 years, advances in DNA technology have allowed the design of diverse molecular detection methods. In this sense, traditional PCR has been adapted for a relatively rapid (approximately, 4-6 h) and qualitative detection of dairy phages from different industrial samples (milk, cheese whey, fermented milks, etc.) with satisfactory detection limits. The increasing demand for quantitative, more sensitive and faster analysis to detect and enumerate phages from dairy samples coupled with the ever-increasing knowledge on phage genomic sequences has prompted the development of specific real-time qPCR methods to specifically detect dairy phages of industrial relevance, demonstrating a high degree of efficiency, sensitivity and precision. An important benefit of these molecular systems is that neither phage particle concentration nor any procedure is required to enrich the samples. Other novel systems, based on different methodologies, have been adapted to indirectly detect dairy phages. Some examples of these methodologies are based on flow citometry and impedimetric measures, which detect phages from morphological modifications of single cells, and from changes of a host biofilm established on a microsensor as a consequence of viral infection, respectively.