Microbial lipid production from food waste saccharified liquid under two-stage process

This study aimed to clarify the composition changes of food waste after being placed for few days and propose a two-stage fermentation method to effectively convert food waste saccharified liquid (FWSL) into lipids by Rhodosporidium toruloides. Food waste generally needs 3-5 days to be transported and stored before treatment. The lactic acid concentration of FWSL produced from 5-days-placed-at-room-temperature food waste reached to 15 g/L. Lactic acid promoted yeast proliferation, and its main mechanism was the conversion of lactic acid into pyruvic acid, which could provide energy for yeast growth through TCA cycle. The optimal lipid concentration in the two-stage fermentation reached to 9.19 g/L, and lipid yield amounted to 0.204 g lipid/g total sugar; the values increased by 44.27% and 60.63%, respectively, when compared with those in traditional fermentation. This study could provide a strategy for food waste treatment closer to industrial production.