Zeaxanthin production by an Antarctic Flavobacterium sp.: Effect of dissolved oxygen concentration and modelling kinetics in batch and fed-batch fermentation

Zeaxanthin is a high-value carotenoid, found naturally in fruits and vegetables, flowers and microorganisms. Flavobacterium genera is widely known for the production of zeaxanthin, in its free form. Nowadays, the production of zeaxanthin from bacteria is still non-competitive with traditional methods. The study of operational conditions is a key aspect for scaling-up. In this work, the influence of dissolved oxygen concentration was studied on zeaxanthin, β -cryptoxanthin and β -carotene production. It was found that 10% pO 2 was the best condition for zeaxanthin production in batch production, reaching a total carotenoids concentration of 3280± 88 µ g/L, with 86% of zeaxanthin conversion. Biomass production, substrate consumption and total carotenoid production kinetics were studied by analyzing carbon and oxygen mass balances, as well as applying the Luedeking-Piret model. To enhance carotenoid production, a fed-batch culture was performed in a bioreactor. Although biomass productivity was similar to that in batch mode, zeaxanthin productivity was higher in the batch conditions, reaching 118 µ g/Lh and 38 µ g/Lh, respectively. The models developed for batch cultures were tested to predict the behavior of the fed-batch culture. A binary model, which considered glucose and oxygen as limiting substrates, presented better results and exhibited a proper fit.