Fermentation of highly toxic reed hydrolysate using Candida glycerinogenes to produce platform compound glycerol

Abstract

Reed, wild plants all over the world, remains underutilized as a fermentation feedstock due to the high inhibitory of its hydrolysate. Most studies on lignocellulose fermentation have focused on ethanol production; however, glycerol, as a platform compound, holds broader application prospects due to its versatility in producing various metabolites. This study aims to enhancing the resistance of Candida glycerinogenes through genetic modifications to improve its resistance to inhibitors. Our results demonstrate that the gene CgLYRM6 demonstrated effective detoxification against a range of aldehyde inhibitors, including furfural, vanillin, benzaldehyde, 2,5-dimethylbenzaldehyde, and 3,4-dimethylbenzaldehyde.The final engineered strain Cg1 carrying LYRM6, TAL1 and UGA2 achieved a glycerol titer of 31 g/L in reed hydrolysate, a 24 % increase compared to the wild type. And glycerol titer reached 40 g/L in the 5 L bioreactor, showing an 60 %increase in production. The strain had shorter fermentation cycle and stronger detoxification ability compared to the control strain. This route enabled simultaneous fermentation and detoxification, providing intermediate metabolites for further conversion and offering a new strategy to utilize undetoxified, alkali-pretreated reed hydrolysate for the production of various metabolites.