The effect of cadmium on culturability, macromolecule synthesis and protein degradation in a marine Vibrio sp.

In this work, we elucidated the adaptation of the marine Vibrio sp. strain S14 to cadmium exposure. Cadmium at a concentration of 50 mug/mL caused a n early complete but transient loss in the capacity of cells to form colonies on agar plates, a rapid inhibition of the incorporation of both [C-14]thym idine into DNA and [C-14]uracil into RNA, while protein synthesis was less affected. Cadmium exposure elicited the de novo synthesis of cadmium-induce d proteins (CDPs). Analysis by densitometry identified at least 24 proteins as being induced during 1 h Cd-stress. 17 of these were also synthesized b y heat-shock and/or starvation, while 7 proteins were found to exclusively respond to cadmium stress. The rate of proteolysis during the first hour of Cd-exposure was approximately 5 times greater than during exponential grow th. In comparison to non-treated cells, 1 h Cd-pre-stressed and 2.5 h pre-s tarved cells were found to recover more rapidly during subsequent Cd-stress .