摘要
A feasible fermentation process for the production of lactic acid(LA),one of the most important food additives,from non-crop feedstocks would help alleviate the challenges of food safety.In this study,215 g/L inulin-rich Jerusalem artichoke powder(JAP)were directly converted into LA without exogenous nitrogen addition under non-sterile conditions via selected Lacticaseibacillus paracasei NJ.The LA concentration,yield,and average productivity reached 144.08 g/L,0.67 g/g,and 4.37 g/L/h,respectively,which can be scalable from 5 L to 50 L bioreactors.The viable counts of Lacticaseibacillus reached to 142.30-301.50×10^(8) CFU/mL,allowing the products a promising probiotic in food additives.Transcriptional analysis revealed that strain NJ utilized inulin mainly via extracellularβ-fructosidase and fructose transporters encoded by the fosRABCDXE operon,and the gene expression within the phosphoenolpyruvate(PEP)-dependent phosphotransferase system(PTS),pyruvate metabolism,and fatty acid synthesis was significantly altered.For strain NJ grown on JAP,the expressions of genes related to amino acid biosynthesis and peptide/amino acid relevant ATP-binding cassette(ABC)transport system were upregulated to fit nitrogen limitation.We found the availability of L.paracasei NJ for high-yield lactic acid from raw JAP and explores the inner changes of gene expression by utilizing inulin,which provide both promising food additives and new perspectives on the understanding of inulin metabolism in Lacticaseibacillus.
基金
supported by the National Key Research and Development Program of China(2023YFE0104900).
