Sustainable lipid and lutein production from Chlorella mixotrophic fermentation by food waste hydrolysate

Bioconversion of food waste into value-added products is a promising way to tackle the global food waste management problem. In this study, a novel valorisation strategy for bioenergy and lutein production via microalgal fermentation was investigated. Significant amount of glucose was recovered from enzymatic hydrolysis of food waste. The resultant hydrolysate was then utilised as culture medium in mixotrophic cultivation of Chlorella sp. to obtain high levels of lipid and lutein, whose accumulation patterns were consistent with molecular analyses. The resultant algal lipid derived from microalgal biomass using food hydrolysate was at high quality in terms of biodiesel properties. Further, in semi-continuous fermentation, the average algal biomass was 6.1 g L^-1 with 2.5 g L^-1 lipid and 38.5 mg L^-1 lutein using hydrolysate with an initial glucose concentration of 10 g L^-1. Meanwhile, the resultant algal biomass was 6.9 g L^-1 with 1.8 g L^-1 lipid and 63.0 mg L^-1 lutein using hydrolysate with an initial glucose concentration of 20 g L^-1, which suggests food waste hydrolysate could trigger algal products preferences. The experimental results of this study suggested the potential of microalgae as a platform for bioconversion of food waste into high-value products, especially sustainable bioenergy.