Effect of fructooligosaccharides and galactooligosaccharides on the folate production of some folate-producing bacteria in media cultures or milk

The present work investigated the ability of Bifidobacterium catenulatum, Bifidobacterium adolescentis, Lactobacillus plantarum, Lactobacillus delbrueckii ssp. bulgaricus and Streptococcus thermophilus to produce folate in milk and complex media. Moreover, the effect of two prebiotics, fructooligosaccharides and galactooligosaccharides, on folate biosynthesis was also evaluated. Levels of the predominant folate forms, i.e., tetrahydrofolate and 5-methyltetrahydrofolate, were determined using high performance liquid chromatography after 0, 6, 10 and 24 h incubation. B. catenulatum (28.82 ± 2.02 μg 100 mL−1) and S. thermophilus (19.03 ± 1.95 μg 100 mL−1) produced the highest level of folate in complex media and milk, respectively. In most cases, the bacteria tested reached the maximum folate levels within 6 h and 10 h of incubation. The inclusion of prebiotics in the culture medium did not stimulate the synthesis of folate by any of the five bacteria studied, although it increased the rate of bacterial growth.