RETENTION OF THE VIABILITY AND PHYSIOLOGICAL-PROPERTIES OF BIFIDOBACTERIA DURING STORAGE BY CRYOPRESERVATION AND LYOPHILIZATION

Cryopreservation in liquid nitrogen and lyophilization were found to b e suitable for a long-term maintenance of B. adolescentis MS-42 cells since both methods provided for the retention of their viability and b iological activity. Optimal cooling protocols were designed (freezing of liquid cultures and concentrated cell suspensions with a cryoprotec tant at a low cooling rate of 4 degrees C/min or freezing of concentra ted cell suspensions without cryoprotectants at a high cooling rate of 100-400 degrees C/min). The introduction of protectants (sucrose, vit amins B, whey, and skim milk) into the freezing medium increased the v iability of bifidobacteria and prolonged their shelf life during stora ge by cryopreservation and lyophilization.