Changes in the Survivability of Marine Vibrio sp. under Hyper KCl Stress in the Presence of Betaine as Well as with Exposure to 37ºC.

Survivability at hyper KCl stress was examined at 30ºC and 37ºC in the presence and absence of an osmoprotectant by using resting cells prepared from marine Vibrio sp. grown at early stationary phase. Survivability was decided by counting colonies. The number of initial cells, 107.1 ± 0.2 (CFU·mL-1), was reduced to 105.1 ± 0.5 and < 101.0 (CFU·mL-1) at 30ºC and 37ºC, respectively, by the exposure of resting cells, that were prepared from cells grown for 8 h at 0.5 M NaCl at 30ºC, to 1.2 M KCl and 50 mM NaCl for 3 h. Betaine externally existed as a final concentration of 50 mM mitigated hyper KCl stress to the resting cells at 37ºC. The number of surviving cells was maintained 104.9 ± 0.3 (CFU·mL-1) when resting cells, 106.5 ± 0.1 (CFU·mL-1), that were prepared from pre-adapted cells to relatively high concentration of KCl in the growth for 10 h at 0.8 M KCl and 50 mM NaCl at 37ºC, were exposed to 1.2 M KCl, 50 mM NaCl, and 50 mM betaine at 37ºC for 3 h. The results indicate that osmoadaptation system(s) in resting cells is temperature sensitive and betaine functions to mitigate hyper KCl stress to the resting cells at 37ºC.