**5.2. Vitamin B12**

600 Lactic Acid Bacteria – R & D for Food, Health and Livestock Purposes

products to produce the bacteriocin in situ [125].

banned in the European Union since 2006 [127].

**5. Lactic acid bacteria as source of vitamins** 

fermentation in yogurt, cheeses and other fermented foods.

of breast and colorectal cancer [130,133].

**5.1. Folate** 

There are at least three ways in which bacteriocins can be incorporated into a food to ameliorate its safety: a) By using a purified or semi-purified bacteriocin preparation as food ingredient. b) By introducing an ingredient that has earlier been fermented with a bacteriocin producing strain. c) By using a bacteriocin-producing culture in fermented

Additionally, bacteriocin production can contribute to the probiotic functionality of intestinal LAB, while in certain cases may be directly responsible for it, with respect to either beneficially modulating the gut microbiota or inhibiting some gastrointestinal pathogenic bacteria [30].

Consequently bacteriocins, derived from LAB can cover a broad field of applications, including the food industry and the medical sector, mainly in combination with other treatments to increase their effectiveness in humans and animals [126]. In the latter, bacteriocins can be used as growth promoters, instead of antibiotics, which have been

Human life cannot exist without vitamins, because they are involved in essential functions e.g. cell metabolism and antioxidant activities. Humans cannot synthesize most of these vitamins, although it is well known that some intestinal bacteria like LAB can produce some vitamins (folate, vitamin B12 or cobalamin, vitamin K2 or menaguino, riboflavin and thiamine) [128,129]. The gut microbiota has been recognized as a source of some watersoluble vitamins, while such vitamins have also been reported as results of the LAB

Folate is the term used to describe the folic acid derivatives, such as the folyl glutamates which are naturally present in foods and folic acid that is the chemically synthesized form of folate, commonly used for food fortification and nutritional supplements. Folate belongs to the B-group of vitamins and participates in many metabolic pathways like the biosynthesis of DNA and RNA and the inter-conversions of amino acids. Moreover, folate possesses antioxidant capacity that protects the genome by preventing free radical hack of DNA [130]. Dietary folate is essential for humans, since it cannot be synthesized by mammalian cells. Folate can be found in legumes, leafy greens, some fruits and vegetables, in liver and fermented dairy products [131], especially in yogurts, where it may be increased depending on the starter cultures used and the storage condition, to values above 200 μg / lt [132]. Epidemiological studies indicated that folate deficiency is associated with a variety of disorders like Alzheinmer's disease, coronary heart diseases, osteoporosis and increased risk

LAB having the ability to produce folate belong to the *Lactobacillus spp (L. lactis, L. plantarum, L. bulgaricus), Streptococcus spp.* and *Enterococcus spp*. Nevertheless, some lactobacilli strains (*L. gasseri, L. salivarius, L. acidophilus* and *L. johnsonii*) used as both starter cultures and Vitamin B12 or cobalamin is required for the metabolism of fatty acids, amino acids, nucleic acids and carbohydrates [134]. Vitamin B12 cannot be synthesized by mammals and must be obtained from exogenous sources like foods or the intestinal microbiota [128]. It has been reported that among the microorganisms some members of the *Lactobacillus spp* have the ability to produce this vitamin. In particular a probiotic strain of *L. reuteri* which exhibits hypocholesterolaemic activity in animals can produce B12 [135].

Vitamin B12 deficiency can cause various pathological disorders that affect the haematopoietic (pernicious anaemia), nervous and cardiovascular system. Furthermore, this deficiency in male animal models influenced the number of offspring which showed growth retardation and decrease in some blood parameters [136].
