Beet red food colourant can be produced more sustainably with engineered *Yarrowia lipolytica*

Synthetic food colourants are widely used in the food industry, but consumer concerns about safety and sustainability are driving a need for natural alternatives. Betanin, extracted from red beetroots, is a common natural red colour but occurs at low levels (~0.2% wet weight), making extraction resource-intensive and wasteful. Here we developed a sustainability-driven biotechnological process to produce red beet betalains—betanin and isobetanin—by engineering the oleaginous yeast Yarrowia lipolytica. Metabolic engineering and fermentation optimization enabled production of 1,271 ± 141 mg l−1 betanin and 55 ± 7 mg l−1 isobetanin in 51 h using glucose as the carbon source in controlled fed-batch fermentations. A life cycle assessment indicates that, at industrial scale (550 t yr−1), this fermentation process would require significantly less land, energy and resources compared with traditional extraction from beetroot. A techno-economic assessment further shows that fermentation-based betanin production could be economically feasible under current market conditions.

Philip Tinggaard Thomsen, Samir Meramo, Lorenzo Ninivaggi, Eleonora Pasutto, Mahsa Babaei, Paulo Marcelo Avila-Neto, Marc Cernuda Pastor, Peyman Sabri, Daniela Rago, Tanmay Utsav Parekh, Sara Hunding, Laura Emilie Jul Christiansen, Sumesh Sukumara, Irina Borodina