Lactobacillus curvatus Strains Specifically Show High Levels of Tolerance to Freeze-Thaw Stress

Tolerance to freeze-thaw stress is an important characteristic in recent fermentation processes. To gain insight into the freeze-thaw tolerance of lactic acid bacteria (LAB), we performed screening experiments and observed that several Lactobacillus curvatus strains showed high freeze-tolerance even in the absence of cryoprotectants. These Lb. curvatus strains also showed high levels of freeze tolerance in a milk fermentation process. Lactobacillus sakei (closely related to Lb. curvatus) was not revealed to be a freeze-thaw tolerant strain. These data indicate that Lb. curvatus has specific mechanisms underlying its tolerance to freeze-thaw stress. ImportanceOur findings demonstrate that Lb. curvatus strains frequently show high levels of freeze-thaw tolerance in both culture and milk and that Lb. curvatus strains are suitable as a model species for investigations of the molecular mechanisms underlying freeze-thaw tolerance in LAB and for applications in fermentation industries.