ABSTRACT
Lyophilized cells in biological preparations exist in a form of artificial anabiosis that in our opinion may be paralleled with natural forms of dormancy caused by environmental stresses (physical, chemical, biological). Activity of bacterial cultures, including probiotic preparations is commonly evaluated as a number of colony forming units (CFU/ml) after plating serial dilutions of bacterial cultures in normal saline. Microbiologists believe that a colony is not always formed from a single cell and real number of cells is somewhat greater. Plating and other culture-based methods also fail to reveal cells that are not readily culturable at the moment of sampling. Such cells may be dormant, sublethally injured or exist in viable but nonculturable state [1-4]. We tested the commercially available kit for differentiating between viable and dead for accuracy when viability of probiotics is assessed.
