Folates biosynthesis by Streptococcus thermophilus during growth in milk.

Aurora Meucci, Lia Rossetti, Miriam Zago, Lucia Monti, Giorgio Giraffa, Domenico Carminati, Flavio Tidona

Food microbiology 2018 Feb

filter terms:

The ability of folate-producer strains of Streptococcus thermophilus to accumulate folates and the expression of two target genes (folK and folP), involved in the folate biosynthesis, were studied during milk fermentation. An over-expression of folK took place only in the early phase of growth, whereas folP was mainly expressed in the mid log-phase of growth and declined thereafter. The accumulation of total folates, which was quantified by a microbiological assay, was strain-dependent. Two major forms of folates, i.e. tetrahydrofolate (THF) and 5-methyl-tetrahydrofolate (5-Met-THF), were identified and quantified by HPLC. With respect to the level accumulated by a weak folate producer (St 383), used as calibrator in the expression experiments and as control in folate quantification in milk, the strains St 563 and St 399 produced 5-Met-THF in amounts significantly higher than THF. The possibility of using selected folate-producer S. thermophilus strains as functional cultures for a bio-fortification of dairy products is discussed. Copyright © 2017 Elsevier Ltd. All rights reserved.

Citation

Aurora Meucci, Lia Rossetti, Miriam Zago, Lucia Monti, Giorgio Giraffa, Domenico Carminati, Flavio Tidona. Folates biosynthesis by Streptococcus thermophilus during growth in milk. Food microbiology. 2018 Feb;69:116-122