FIG. 3.

Induction of β-glycosidase levels by nutrient down shift. (A) Growth of S. solfataricus in sucrose medium with yeast extract (open symbols) and in sucrose medium (closed symbols), OD₅₄₀ (squares), and β-glycosidase specific activity (circles). (B) Western blot analysis of β-glycosidase levels. Lane 1 and 2 contain 40 and 4 ng recombinant β-glycosidase, respectively; lanes 3 to 9 contain S. solfataricus extracts following a nutrient down shift from growth in sucrose medium with yeast extract to a sucrose medium. Lanes and sample times after onset of the shift: 3, 0 h; 4, 1 h; 5, 2 h; 6, 3 h; 7, 4 h; 8, 5 h; 9, 7 h. Cell extracts were loaded in 24-μg amounts per lane. The arrowhead on the right indicates the position of β-glycosidase; molecular mass markers in kilodaltons are shown on the left.