Detection of Bacteriophages in Milk Products

Abstract

Bacteriophages are the main microbiological problem in the fermentative dairy industry. Selection of appropriate methods of phage detection, identification and enumeration may help select optimal anti-phage strategies to avoid economic losses. These methods can be classified into three groups: classical microbiological assays, PCR-based methods and microscopy-based approaches. Other methods have also been proposed and tested, but their applicability is restricted. Classical assays still remain the gold standard; they give conclusive results and only detect infective phages. They are time consuming but might be improved via automation and miniaturization. PCR methods detect the presence of viral DNAs; though they are expensive, they can identify and, in some cases, quantify phages. However, they fail to discriminate between infective and inactivated phages, and might overlook the detection of new, unknown phages. Notwithstanding, quantitative PCR is very fast and allows simultaneous phage identification and enumeration, thus arising as a complementary tool to quickly decide the destiny of raw milk in dairy facilities. Microscopy and other sophisticated techniques are expensive and still not designed to routine phage detection, but some of them could be refined and used with this aim in the future.