3.2.2. Foaming-dependent feeding
In foaming-dependent feeding, the feeding was intermittent in response to observations of foam on the surface of the fermentation broth. The fermentation profile with demarcation of the feeding events is shown in Fig. 4. The fermentation was relatively well controlled as evidenced by the fairly smooth profiles of biomass
growth and lipase activity (Fig. 4). The peak biomass concentration was fairly high at 53 g L−1 as was the peak lipase activity (195 U L−1) (Fig. 4). The high lipase titer was simply a consequence of the high biomass concentration and the biomass-specific lipase productivity was only modestly better (0.09 U g−1 h−1; Table 1) in comparison with that data for batch and pH-stat fed-batch fermentations (Table 1).