Supercritical Carbon Dioxide-Assisted Recovery of Endotoxin-Free Lycopene from Escherichia coli

Abstract

Biotechnological production of lycopene from renewable sources has advanced significantly. However, the downstream process is often overlooked. Being an intracellular molecule, hardly soluble in solvents, and highly prone to oxidative degradation, lycopene is difficult to purify from fermentation broth. Moreover, there could be contamination from endotoxins from the production host. In this article, we established a green and efficient workflow for extracting lycopene from Escherichia coli. We first genetically modified our E. coli strains and successfully achieved over a 99% reduction in endotoxin levels. Next, we explored a two-step, one-pot method using supercritical carbon dioxide (scCO₂) as a green solvent to dry the E. coli wet biomass and extract lycopene. Up to 99% of lycopene was successfully recovered. Interestingly, we uncovered an inverse correlation between endotoxin levels and the lycopene concentration in two fractions. This observation suggests the potential of scCO₂ to separate endotoxins from the extracted lycopene effectively. These discoveries warrant future investigations in the realms of bioprocessing and extraction methodologies.