3.3. Production and biochemical characterization of recombinant
A. niger GH1 invertaseThe culture with the selected KM71invGS strain had a cell densityof 79 g/L DCW at the end of the glycerol-fed batch step. In the induction step, cellular growth increased exponentially with a specific growth rate () of 0.012 h−1, reaching a cell density of 118 g/L DCW at 72 h induction. The total methanol consumption was 1.5 L.
The time profile of the extracellular invertase production increased up to 498 U of invertase (Fig. 1A) during the whole induction step (from 0.2 to 0.6 g protein/L). In addition, periplasmic invertase activity also increased up to 3776 U of invertase (from3.9 to 14.9 g protein/L). Therefore, the total invertase that was produced at 72 h of induction was 4274 U, which corresponds to1018 U/L of culture medium.