Glycerol for batch phase and glucose for fed-batch phase was the most successful carbon source combination. During batch phase, by-products were detected when glucose was used, despite maintaining DO at values higher than 35 % . Also, the presence of cell aggregates was detected affecting the reproducibility and operability of the bioprocess.
Conversely, glucose was the best substrate for fed-batch phase. When working at C-limiting conditions, neither by-products nor aggregates were detected and Fab production levels were comparable to those obtained with glycerol. In addition, the lower heat yield (YQ/X) and oxygen to biomass yield () for glucose-supported cultures made this substrate the best alternative from an industrial operational point of view.
In addition, the effect of specific growth rate on fed-batch Fab production was studied. Medium and high ¦Ì (0.10 and 0.15 h?1) set-points showed similar Fab production yield. However, in terms of total and volumetric productivity, higher ¦Ì was the best process condition.