Probiotic lactobacilli strains may increase folate concentrations of media supplemented with fruit by-products

LEBLANC, JEAN GUY; ALBUQUERQUE, M.A.C.; SAAD, S.M.I.; BEDANI, R.

San Miguel de Tucuman

Simposio; V Simposio Internacional de Bacterias Lácticas; 2016

CERELA

Soy products are considered interesting alternatives to dairy foods due to their nutritional and functional characteristics; however, soymilk has low concentrations of some B Group vitamins due to processing. On the other hand, it has been shown that certain strains of Lactic Acid Bacteria are able to synthesize folate. Thus, the ability of three starter Streptococcus thermophilus (ST-M6, TA-40 and TH-4) and four probiotic lactobacilli (Lb. acidophilus LA-5, Lb. rhamnosus LGG, Lb. fermentum PCC, Lb. reuteri RC-14) to produce folates during the fermentation of four soymilk formulations (F1: soymilk (SM); F2: SM with 1% (m/v) of passion fruit by-product (PFBP); F3: SM with 1% of fructooligosaccharides (FOS); F4: SM with 0.5% of PFBP and 0.5% of FOS) was evaluated. Each strain was inoculated (4-5 log cfu/ml) in each formulation as pure cultures and incubated statically at 37 °C for 24 h. Samples were taken at 0 and 24 h to quantify folate concentrations using a microbiological assay. Strains ST-M6 and TH-4 were the best folate producers in all formulations significantly increasing initial vitamin concentrations (F1, from 134±19 to 999±56 and 957±89 ng/mL, respectively; F2, from 177±45 to 881±81 and 787±37 ng/mL; F3, from 149±44 to 1325±77 and 1229±103 ng/mL; F4, from 156±31 to 748±65 and 1250±77 ng/mL). LA-5 increased the folate content of F2 from 177±45 to 293±18 ng/mL and this was a surprising result since the folate biosynthesis genes were not found in the published genome of this strain. After 24h, LGG increased the folate content of F1 (from 134±19 to 376±16 ng/mL), F3 (from 149±44 to 194±32 ng/mL) and PCC of F2 (177±45 to 203±20 ng/mL) and F4 (156±31 to 376±94 ng/mL). RC-14 increased folate levels of F3 (149±44 to 295±42 ng/mL) and TA-40 consumed the folate in all the formulations. To the best of our knowledge, this is the first study where microorganisms were used to increase folate concentrations in a fermented soy product and reinforces the notion that folate production is strain and substrate specific. The use of probiotic strains to bio-enrich soy-based foods could improve their value and prevent the need for fortification with synthetic folic acid.