Towards a sustainable Dunaliella salina microalgal biorefinery for 9-cis β-carotene production

Valorisation of the efficacy of 9-cis beta-carotene in treating atherosclerosis, psoriasis, and inhibiting atherogenesis and retinitis pigmentosa is becoming increasingly urgent, but supplies of 9-cis beta-carotene are scarce and this compound is difficult to synthesise chemically, unlike the much more common all-trans form. Innovative products, processes and services in an algal biorefinery that rely on renewable biological resources instead of fossil fuel alternatives offer the potential to lower the energy costs of traditional chemical processes and reduce carbon emissions, water usage and waste. In 2013, the European Commission supported development of 4 microalgal biorefinery projects to assess the potential for innovative approaches to tackle the major challenges intrinsic to the development of the algae biorefineries. One of these was the D-Factory (KBBE.2013.3.2-02) which sought to evaluate requirements for sustainable, industrial-scale production of Dunaliella salina and extraction of its carotenoids, especially 9-cis beta-carotene in a CO₂ microalgae biorefinery. Here we present findings of the D-Factory project and propose a way forward for industrial-scale production of 9-cis beta-carotene using biotechnology based on Dunaliella salina biomass. Cultivation improvements are able to deliver more than double the current levels of productivity, with increased sustainability, whilst the use of natural hyper-accumulating carotenogenic strains combined with the use of red light to boost production of the beta-carotene pathway, will increase the relative concentration of 9-cis beta-carotene in extracts of carotenoids with consequent improvements in downstream processing. These developments pave the way for acquiring data for a Medicine Licence and prepare the market for entry of novel 9-cis beta-carotene products.