Green directional conversion of food waste into glycerol in a two-step differentiation enzymolysis and facultative fermentation using Saccharomyces cerevisiae: Performance assessment and mechanism

• Published in: Biomass & bioenergy 2024-10, Vol.189, p.107360, Article 107360
• Main Authors: Zhu, Siyu, Li, Sinuo, Rene, Eldon R., Cheng, Xinhui, Ma, Weifang
• Format: Article
• Language: English
• Subjects: Enzymolysis; Facultative fermentation; Food waste; Functional genes; Glycerol
• ISSN: 0961-9534
• DOI: 10.1016/j.biombioe.2024.107360

Valorization of food waste into high value-added glycerol was designed and prepared via directional green transformation using multi-enzymolysis saccharification coupled facultative fermentation by Saccharomyces cerevisiae. The optimal conditions for the first step of multienzyme hydrolysis and the second step of facultative fermentation were 55 °C and pH 5.0 for 6 h, 30 °C and pH 7.0 for 70 h, respectively. The glycerol yield efficiency and kinetic rate constant were 73.6 % (w/w) and 0.681 h−1 for dry component of food waste, while the other 27.4 % was utilized as the growth energy substrate. The key points of transformation were the synergistic directed enzymolysis to produce 3 % glycerol and 95 % reducing sugars. Furthermore, the reducing sugars were converted into glycerol by switch the metabolic pathway from ethanol into glycerol through the quantitative expression of functional gpd1 and gpp2 genes activated GPD and GPP enzymatic activity and synchronous inhibition of adh gene for glycerol production with Na2SO3 regulation. The economic income was 135.52 USD/ton for converting 80 % water content of kitchen waste into glycerol. This finding provided an economic value-added approach to produce high-value glycerol for cost-effective recycling of food waste using commercial yeast. [Display omitted] •Glycerol produced from food waste through two-step green directional conversion.•Food waste hydrolysate into 95 % reducing sugar and 3 % glycerol.•Glycerol yield was 73.6 % through reducing sugar microaerobic fermentation.•Glycerol production was controlled by functional enzyme genes gpd1 and gpp2.•Economic income was 135.52 USD/ton for kitchen waste conversion to glycerol.