A process for the simultaneous production of folate and vitamin B12 in whey using a synergistic co-culture of lactic and propionic acid bacteria

Abstract

Sufficient intake of folate in industrialized countries is critical due to low folate concentrations in the daily food. Recent data also indicated the importance to maintain balance between folate and vitamin B12. In the present study, high folate producing LAB (Lactobacillus plantarum SM39) and vitamin B12 producing PAB (Propionibacterium freudenreichiiDF13)were selected fromaprevious screening for the development of a co-culture process aiming at high and simultaneous production of natural folate and vitamin B12. Aeration conditions, LAB-PAB inoculation levels, andmediumcomposition were optimized and the co-culture fermentation was compared to single cultures. Highest vitamin yields of 8308±136 ng/mL total folate and 577±142 ng/mL vitamin B12 were obtained in a 2-step fermentation process (3 days anaerobic/4 days aerobic) in whey permeate supplemented with 1% yeast extract and an LAB:PAB inoculation level of 5 and 7 Log cfu/mL, respectively, with the addition of 5mg/L cobalt chloride, 15mg/L DMBI, and 10mg/L pABA. Folate yields were about 10-fold higher than values reported in literature for natural fermentation, and were comparable to production of genetically optimized strains. A mutation in the promoter region of the folate gene cluster of L. plantarum SM39 may explain the very high folate yield compared to other L. plantarum strains. The main folate derivative produced by L. plantarum SM39 was identified as 5-formyltetrahydrofolic acid. Compared to co-cultures, less folate was produced in L. plantarum SM39 single cultures yielding 6280±264 ng/ml; contrary, vitamin B12 production was higher in P. freudenreichii DF13 single cultures (1647 ng/mL) compared to co-cultures. The LAB-PAB co-culture process developed in this work led to a simultaneous and synergistic high production of folate and vitamin B12 and a bioingredient which could be applied to increase natural folate intake in the population while ensuring adequate vitamin B12 levels.