Mapping biosynthesis pathway of natural folate during Lactiplantibacillus plantarum subsp. plantarum fermentation in...

Folate is an important one-carbon cycle donor involved in the synthesis of purines, thymine, pantothenic acid, serine and glycine. The present study aimed to explore the capacity of Lactiplantibacillus plantarum subsp. plantarum (L. plantarum subsp. plantarum) to synthesize folate in fermenting MRS and purple cabbage juice (PCJ). The mechanism underlying folate biosynthesis was investigated by transcriptomics. We aimed to find important genes and transcription factors involved in folate production by analyzing gene expression during L. plantarum subsp. plantarum fermentation.

The results showed a 44% increase in total folate content in the PCJ medium, with 5-methyltetrahydrofolate (5-MTHF) contributing to a substantial 28% of this increase, whereas no folate was detected during MRS fermentation. The mechanism of folate production during the fermentation involved the coordinated regulation of multiple genes. The expression of some key genes (aroC, pabA, folE, folA and MTHFR) was upregulated during fermentation, and the expression of MTHFR, a gene related to 5-MTHF synthesis, was increased by 8.4 times. These genes play roles in different steps of the folate synthesis pathway, including substrate synthesis, metabolic regulation and catalytic reactions.

Our results revealed the expression of all genes involved in the biosynthesis of 5-MTHF during L. plantarum subsp. plantarum fermentation, indicating the integrity of its biosynthetic pathway. The findings provide a scientific basis for folate production by optimizing fermentation conditions, further helping research on folate synthesis in other fermented foods. © 2024 Society of Chemical Industry.