Shuhai M. Biological and physico-chemical properties of phages of lactic acid bacteria isolated during the manufacture of fermented dairy products

The thesis examines biological properties of the phages active to meso- and thermophilic lactic acid bacteria (LAB) and widespread at the dairy plants of Ukraine. The negative influence of high-titre phages on quality and level of epidemiological security of the end product was researched. It was established that the problem of preventing mass phagolysis lies in the necessity of decreasing the phage titre in the end product to values below 106 PFU/ml. For the first time in Ukraine cultures of the thermophilic streptococci were examined for their phage sensitivity and was shown the ability of phages to cross lyse cultures of mesophilic (Lactococcus lactis) and thermophilic (Streptococcus salivarius ssp. thermophilus) LAB. The morphologico-structural organization of the phages and structure of phages proteins was studied. Investigated was the sensitivity of phages to physico-chemical factors and stability of viruses during preservation in different conditions.