Folate: Relevance of Chemical and Microbial Production

Folate, water-soluble B9 vitamin, is produced by green plants and some microorganisms. It acts as a coenzyme in the transfer of one-carbon units in many biosynthetic and cellular processes and is essential for cell division, embryonic and foetal development and maintenance of cardiovascular and neurologic functions. Folates occur in a variety of foods, especially in leafy vegetables, mostly as derivatives of the reduced form tetrahydrofolate (THF). Vitamin supplements and food fortification utilise chemically synthetised folic acid (FA), an oxidised form which is more stable and bioavailable. At present, FA is mainly produced via chemical synthesis. In fact, even if numerous studies have shown that certain lactic acid bacteria (LAB) can synthetise the vitamin de novo, the biotechnological production of folate has never been competitive with chemical synthesis. However, appropriate combination of selected LAB, such as Lactococcus lactis and Streptococcus thermophilus, can be used to enrich fermented foods in this vitamin, as successfully demonstrated for dairy products. Furthermore, the use of folate-producing Bifidobacterium strains can be regarded as a specific use of probiotics. Human and animal trials proved that the administration of folate-producing bifidobacteria positively affected folate level in plasma, indicating that the vitamin is produced in vivo by the probiotic strains and absorbed.