Ability of lactobacilli isolated from traditional cereal-based fermented food to produce folate in culture media under different growth conditions

- Folate biosynthesis capacity is species and strain dependent.
- Folate biosynthesis is highly influenced by time and medium composition.
- Folate production by a consortium of strains is not cumulative.

Folates are essential vitamins (B9). Lactic acid bacteria (LAB) can be used to increase the folate levels in foods during fermentation. Here, 151 LAB strains isolated from fermented food were screened for folate production. Folates were extracted by heat treatment coupled with enzymatic extraction. Total, extra- and intracellular folate were quantified by microbiological assay. Most Lactobacillus plantarum and Lactobacillus fermentum strains synthesized folate, Pediococcus pentosaceus strains consumed folate, and Pediococcus acidilactici strains either consumed or produced. Seven strains were further examined for their ability to synthesize or consume folate during growth in rich folate medium (MRS) and folate-free medium (FACM). For most strains, the differences observed in MRS were attenuated in FACM. L. fermentum 8.2 and L. plantarum 6.2 produced the highest levels of folates in MRS (97 and 93 ng·mL−1) and FACM (29 and 44 ng·mL−1). In most cases, production reached a maximum from 9 or 11 h to 24 h. Incubations in FACM with mixed LAB cultures showed that folate production is not additive. We demonstrated how biosynthesis of folate by LAB depends on species, strains, and is highly influenced by time and medium composition. Characterized LAB strains can be further explored for novel folate bio-enriched functional food.