Metabolomic profiling of goji fermentation: enhancing functional metabolites with high-glucose-adaptive LAB

Hyper-osmotic stress in high-sugar fruits inhibits the fermentation performance of lactic acid bacteria (LAB). Besides, there is a prevailing trend of low-sugar diets for health concern. Therefore, it is essential to develop LAB strains with high-sugar tolerance and efficient sugar metabolism. In this study, three high-sugar-adaptive strains (2-12 mutations) were obtained through random mutagenesis and screening at 150 g/L glucose. When applied to high-sugar goji juice fermentation, they reduced glucose from 92.26 to 28.85 g/L, reached 2.56*10⁹ CFU/mL, and shifted the sensory profile from sweet and herbal to fruity and pleasantly sour. Metabolomics revealed enrichment of bioactive metabolites such as indole-3-lactate (+22.32%), linoleate (+16.37%) and spermine (+64.50%) in strain LP-4-3*. Mechanistically, high-glucose-adaptive LAB accumulated more maltose, galactitol, and glycosylated phenolic compounds to alleviate osmotic pressure induced by high glucose. This study highlights the potential of high-glucose-adaptive LAB in developing low-sugar and health-promoting fermented fruit juices.