Intensification and techno-economic analysis of a biocatalytic process for coniferol production from ferulic acid: An innovative strategy for lignin valorization

Coniferol, as a natural monolignol, acts as a chemical building block for various high-value compounds. However, the current petrochemical synthesis of coniferol and its limited scalability raise environmental and cost concerns. A biocatalytic method for coniferol production from its natural precursor, ferulic acid, was previously developed using an engineered cell factory that co-expresses carboxylic acid reductase and aldo-keto reductase. The present study focused on investigating the limiting factors of coniferol production and optimizing the process using the design of experiments and fed-batch approaches. By introducing novel parameters, including an inoculum of 0.25 g/L cells and a starting concentration of 5.0 mM ferulic acid, followed by two fed-batch additions of 2.0 mM ferulic acid and 3.7 g/L glycerol, coniferol production was enhanced by a factor of 2 (reaching 1.6 g/L). The scale-up process in a 1 L bioreactor and its intensified technical and economic analysis demonstrated its cost-effectiveness. Considering two different purchase prices for the ferulic acid of $5.0 and $650.0 per kg, the payback time was estimated at 3.3 and 3.2 years, respectively, and the minimal selling price of coniferol to obtain a IRR of 30% was calculated as $4.2 and $5.0 per gram, which is significantly lower than the current market price. In conclusion, the findings illustrate a biocatalytic approach for producing valuable compounds with potential applications in various industries, including cosmetics and pharmaceuticals. Furthermore, this approach contributes to developing sustainable and profitable biorefinery processes, paving the way for future initiatives focused on biocatalytic lignin valorization.