Survival of strains of lactic streptococci during frozen storage

Summary Sixteen single-strain cultures, 10 of Streptococcus cremoris, 3 of Str. lactis and 3 of Str. diacetilactis were examined for their ability to withstand freezing and storage at –17·8 and –23·3°C. The numbers of surviving bacteria decreased as storage time increased. For the majority of strains, the survival rate was greater at the lower temperature. At both storage temperatures there were differences between the percentages of surviving bacteria for different strains. The results suggest that the relative proportion of strains in mixed cultures would not remain constant under frozen storage.