DIVERSITY OF PHYSIOLOGICAL AND BIOCHEMICAL PROPERTIES WITHIN YEAST SPECIES OCCURRING IN ROKPOL CHEESE
 
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Pol. J. Food Nutr. Sci. 2005;55(3):257–261
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ABSTRACT:
Sixty seven representatives of the seven yeast species existing in Polish blue veined cheese Rokpol were examined for their ability to grow at low temperature and low water activity (aw), to assimilate lactose, lactic and citric acids, produce extracellular proteolytic and lipolytic enzymes and killer toxins. All strains examined were able to grow at 10oC. At the same temperature in the presence of 5% (aw = 0.961) and 10% NaCl (aw = 0.902) the best growth was displayed by the strains of C. famata and C. sphaerica, but yeasts G. penicillatum and C. lipolytica were completely inhibited at aw 0.902. All strains of C. famata (32/32), C. sphaerica (13/13), C. intermedia (5/5) and C. kefyr (4/4) but none of C. lipolytica (0/5), S. kluyveri (0/4) and G. penicillatum (0/4) were able to metabolise lactose. Only C. lipolytica strains tested utilised both lactic and citric acids. These abilities in the case of other yeast species were strain dependent. The highest activities of both proteolytic and lipolytic extracellular enzymes were demonstrated for C. lipolytica strains. Other yeast species investigated varied in the proportion of strains which were positive and the activity level of proteolytic and lipolytic enzymes. Strains of C. famata and C. sphaerica produced killer toxins which were active exclusively against representatives of C. lipolytica species.