A strain Lactobacillus acidophilus NCFM Howaru Dophilus is a probiotic bacterium commonly available in dairy products and dietary supplements since 1970s. Similar to other strains of Lactobacillus species, the culture does not dispose of genes necessary for the synthesis of vitamins, aminoacids or cofactors. On the other hand, its genome encodes a plurality of enzymes involved in NCFM strain’s transport and fermentation systems^[1]. Developed uptake and metabolism chains are important for its growth in its common habitat – a nutritionally rich colonic mucosa.

The strain is referred as probiotic microorganism. It is tolerant of low pH allowing it to survive in inhospitable conditions of a gastrointestinal system^[2]. Its activity in colon is the cause of its positive effects on a human body. Its antimicrobial and anticarcinogenic activity, ability to strengthen the immune system, to alleviate indigestion and lactose intolerance have been the subject of many studies^[3,4,5].

Although its metabolism, genetics and clinical effects have been characterized comprehensively, there is still a lack of information about its viability in a wider temperature range. Therefore, this work deals with the examination of NCFM strain’s viability during its storage at stable temperature 6 °C and unstable temperature in a fridge. Considering types of products containing Lb. acidophilus NCFM Howaru Dophilus available for Slovak consumers, experiments were realized in an artificial medium of MRS broth and in a real medium of ultra heat treated cows’ milk.

In nutritionally rich environment, Lb. acidophilus NCFM was able to survive and even to metabolize the media components, what was manifested by lowering of pH value. The relevant decrease of viable cells was observed about 30 days after inoculation into MRS broth. The average rate of decrease was approximately two times higher in experiment in MRS broth at unstable temperature (-0.149 log CFU.ml^-1.d^-1) compared with that at stable temperature (-0.079 log CFU.ml^-1.d^-1). The experiment in 10 ml of MRS broth, where NCFM strain was previously cultivated overnight, showed that in a nutritionally exhausted environment the decrease of viable cells started practically immediately and the average rate of decrease was -0.137 log CFU.ml^-1.d^-1. During the experiments realized in milk media the relevant decrease of viable cells was not observed in 30 days, at all. Results suggest that due to its ability to survive, Lb. acidophilus NCFM Howaru Dophilus is appropriate for production of probiotic milk products and dietary supplements with shelf-life over 4 weeks.