SALT STRESS IS AN ENVIRONMENTAL SIGNAL AFFECTING DEGRADATIVE ENZYME-SYNTHESIS IN BACILLUS-SUBTILIS

Growth under conditions of salt stress has important effects on the sy nthesis of degradative enzymes in Bacillus subtilis. Salt stress stron gly stimulates the expression of sacB, encoding levansucrase (about ni nefold), and downregulates the expression of aprE, encoding alkaline p rotease (about sixfold). It is suggested that the DegS-DegU two-compon ent system is involved in sensing salt stress. Moreover, it has been s hown that the level of sacB expression strongly depends on the growth conditions; its expression level is about eightfold higher in cells gr own on agar plates than in cells grown in liquid medium.