Rather than having sequential carbon co-utilisation with preferential
glucose oxidation, glucose feeding at the onset of the production
phase enabled to achieve a simultaneous lactobionic and
gluconic acid production in a whey/glucose co-fermentation
(Fig. 6). Interestingly, P. taetrolens cells started to progressively
uptake the gluconic acid formed upon glucose depletion.
Therefore, the simultaneous co-production of both sugar organic
acids was reliant on the cultivation mode adopted. Whereas batch co-supply of glucose led to a preferential hierarchy glucose oxidation
with low-yield gluconic acid production, glucose feeding
resulted in a co-production system with a nearly complete substrate
bioconversion (98%).