Characterization of folate production and probiotic potential of Streptococcus gallolyticus subsp. macedonicus CRL415

Abstract

Mandatory fortification of foods with folic acid is being questioned by many scientists principally because of the potential adverse secondary effects associated with their excessive consumption. It has been shown that selected strains of lactic acid bacteria (LAB) are able to produce natural forms of folate and these could be included in foods to prevent deficiencies without causing adverse effects. The aim of this study was to evaluate folate production and fol gene expression by Streptococcus gallolyticus subsp. macedonicus (S. macedonicus) CRL415 under different growth conditions in vitro and to assess its potential probiotic application. Results showed that glucose as the principal carbon source, and incubation at 42 °C under controlled pH conditions (6.0) increased folate production, fol gene expression, and growth of S. macedonicus CRL415. This strain was able to produce elevated folate concentrations during milk fermentation without the need of prolonged incubation times and was able to resist conditions simulating the gastrointestinal tract. In addition, S. macedonicus was susceptible to all required antibiotics, and had a good adhesion level to intestinal cells in vitro, making it a promising candidate for biotechnological application as functional starter cultures in the dairy industry.