SIMULATION OF INTERACTION OF PHAGE ASSOCIATIONS AND STARTER MICROFLORA OF CHEESE-MAKING ENTERPRISES.PART 1. LYTIC PROPERTIES OF PHAGE ASSOCIATIONS

The common cause of lactic acid process braking in the production of fermented foods is bacteriophages which determine the significance of phage problem for cheese-making and relevance of research. The objective of the research was to conduct phage monitoring of cheese-making enterprises with the purpose of studying the parameters of interaction of phage associations (FA) reflecting adequately the phage pool of the enterprise and lactic acid bacteria. The research objects were cheese whey substrates, positioned as multistrain bacteriophage substrates (MBS). The results of the study of MBS phage content selected in two cheese- making enterprises of the Altai territory ("S" and "B") are presented. The presence and titer of phages in the substrates were determined by conventional methods of phagolysis using liquid and agar-nutrient media. 142 collection (indicator) cultures of mesophilic lactococcal in relation to the FA presumably contained in MBS were screened. The high contaiminating phage background of MBS and considerable differentiation of lytic parameters (spectrum/level) FA at each enterprise have been determined. Indices of lytic activity (ILA) of FA S1 24/04/13/B5, FA S2 24/04/13/B7 and S4 27/05/13 F defined for the Lc. lactis (73 strains) sample were 0.26, 0.23 and 0.19 respectively. The same index for three FA samples relative to Lc. diacetylactis (50 strains) was lower and amounted to 0.04. The values of ILA in FA B2 13/05/14; FA B4 15/07/14 and FA B6 16/09/14 for "total" sample (128 strains) were in the range from 0.06 to 0.28. Almost the same variability of ILA corresponded to the «total» sample of Lc. lactis (76 strains). The varying range of ILA of the same FA against 52 cultures Lc. diacetylactis was "from 0.04 to 0.35". Theobtained data confirmed the uniqueness of phage pools at various enterprises+, high probability of cell phagolisis of starter associations of microorganisms and the necessity to improve "antiphage" methods in cheese-making.