Figure 4
Effect of lactose concentration on protein expression in PYA8 medium. Coomassie stained SDS-PAGE of the total protein extract after small scale cultures in PYA8 medium with different lactose concentrations. 5 μg of soluble protein extract were loaded in each lane. Lane 1 1 mM lactose; lane 2 5 mM lactose; lane 3 1 mM lactose + 1 mM lactose after 3 h; lane 4 5 mM lactose + 5 mM lactose after 3 h. Induction was started at 0.6 OD600 and continued for 20 h post induction. Using 1 mM lactose provided the best yield of recombinant protein over total protein.