Restructuring the sunflower-based biodiesel industry into a circular bio-economy business model converting sunflower meal and crude glycerol into succinic acid and value-added co-products

A novel bio-economy business model for production of bio-based succinic acid and value-added co-products has been developed using biodiesel industry by-products. Sunflower meal (SFM) fractionation resulted in an antioxidant-rich extract via aqueous ethanol extraction and a protein concentrate stream via NaOH recycling using ultrafiltration. Solid state fermentation (SSF) by Aspergillus awamori using untreated SFM resulted in the production of cellulase, β-glucosidase, xylanase, protease and phytase. After the extraction of co-products, the residual SFM was hydrolysed via thermochemical and enzymatic treatment using crude enzymes resulting in conversion yields of 0.23 g g⁻¹ total Kjeldahl nitrogen to free amino nitrogen, 0.56 g g⁻¹ cellulose to glucose and 0.92 g g⁻¹ hemicellulose to sugars. The SFM-derived hydrolysate was used in fed-batch cultures of Actinobacillus succinogenes leading to 34 g L⁻¹ succinic acid with a yield of 0.6 g g⁻¹ and a productivity of 0.71 g L⁻¹ h⁻¹. Crude glycerol supplemented with SFM hydrolysate resulted in 69.1 g L⁻¹ succinic acid with a yield of 0.39 g g⁻¹ and a productivity of 1.26 g L⁻¹ h⁻¹ by Yarrowia lipolytica PSA02004. SFM was efficiently used for co-product extraction, fermentation medium production and on-site crude enzyme production via SSF.