Abstract
The bioconversion of low-value food industry by-products into high-value compounds through microbial processes represents a promising route toward circular bioeconomy. This study explored the potential of the green microalga Chromochloris zofingiensis to grow mixotrophically using nutrients derived from industrial by-products. After preliminary screening on simple sugars and organic nitrogen sources, four by-products were selected: beet blackstrap molasses (MOL), cheese whey permeate (CWP), spent brewery yeast (SBY), and corn steep liquor (CSL). C. zofingiensis showed high productivity on all substrates, achieving up to fourfold higher biomass daily yield compared to autotrophic controls (0.4 g/L/d with MOL or CSL vs. 0.1 g/L/d in BBM). Among all substrates, CSL exhibited the most pronounced effect, yielding up to 2.29 g/L dry weight biomass with 5 g/L supplementation, over 3.5 times higher than controls. Pigment productivity was maximized with corn steep liquor at 5 g L?¹, reaching 7.80 mg L?¹ d?¹ total carotenoids and 1.41 mg L?¹ d?¹ astaxanthin, about 5.4 fold and 4.9 fold higher than the control, respectively.
