Interrelation between synthesis and uptake of ectoine for the growth of the halotolerant Brevibacterium species JCM 6894 at high osmolarity.

The growth of a halotolerant Brevibacterium sp. JCM 6894 was examined in the presence of compatible solutes such as glycine betaine, ectoine (2-methyl-4-carboxy-3,4,5,6-tetrahydropyrimidine) and ectoine derivatives. The effect of competition between their uptake and synthesis in the cells was subjected to osmotic shift towards the higher salinity. Among each solute examined the supplement of ectoine or hydroxyectoine exhibited a remarkable stimulation on the growth of strain JCM 6894, regardless of the range of osmotic shifts, where the largest was 0-->2 M NaCl, the intermediate was 1-->2 M NaCl, and no shift was 2-->2 M NaCl. The growth rates of this strain were dependent on the amount of ectoine taken up, which was conspicuous for the largest osmotic shift and during the first few hours of incubation after transfer. The cells subjected to 1-->2 M NaCl and 2-->2 M NaCl transfers took up less ectoine and this resulted in lower growth rates than those of cells with the largest osmotic shift (0-->2 M NaCl). The role of other compatible solutes which accumulated is discussed in relation to growth stimulation of strain JCM 6894.