## 1 Introduction  
Fermentation is a biochemical process that chemically transforms organic matter as a result of the enzymatic activities of microorganisms. This process, which has been used throughout history for various purposes such as food preservation, increasing nutritional value, and flavor development, has an important place in modern biotechnology and the food industry. Fermentation can be carried out by microorganisms through different metabolic pathways [1,2]. The most common types of fermentation include lactic acid, ethanol, and acetic acid fermentation. Lactic acid fermentation is characterized by the conversion of carbohydrates into lactic acid and is especially important in terms of functional effects such as food preservation, flavor development, production of bioactive compounds and probiotic properties. This process serves as a basic mechanism in the production of many foods such as yogurt, kefir, and fermented vegetables [3]. The process in which lactic acid fermentation is best observed is milk fermentation. In milk fermentation, lactic acid bacteria (LAB) convert lactose into lactic acid. In this process, by lowering the pH level of the milk, the development of pathogenic microorganisms is prevented and thus the shelf life of the products is extended [4, 5, 6]. LAB not only cause and protect the production of new and different foods from the basis of food durability. At the same time, they can provide functional properties that positively affect health, such as probiotic properties, antioxidant, antimicrobial and antihypertensive activities and/or exopolysaccharideacharide (EPS) production ability and aroma compound production ability, which provide positive effects on the product from a technological perspective [7,8]. One of the most important of these features is the probiotic feature. It is known that LAB, especially _Lactobacillus acidophilus_ and _Bifidobacterium bifidum_ species, have probiotic properties that settle in the intestinal flora of living beings and positively support their immune systems [8,9]. Some LAB stand out with their vitamin production abilities. For example, some strains of _Streptococcus thermophiles_, _Lactobacillus delbrueckii_ subsp. _bulgaricus_, _Lactobacillus helveticus_, _Lacticaseibacillus rhamnosus_, _Loigolactobacillus coryniformis_, _Limosi lactobacillus reuteri_, _Lactobacillus fermentum_, _Leuconostoc lactis_, _L. acidophilus_, and _B. bifidum_ species are known to have the ability to synthesize vitamins-B9 (folate), -B12 (cobalamin) -B7 (biotin), -B6 (pyridoxine), -B3 (nicotinic acid), or -K2 (Menaqinone-7) [10, 11, 12, 13, 14]. [PERSON] et al. [14] reported that the recommended daily intake of vitamin K should be 90 \(\upmu\)g for women and 120 \(\upmu\)g for men. Vitamin K, obtained from the diet in its quinone form, is transferred into the bloodstream for utilization. Long-chain menaquinones, such as MK-7 and MK-10, are synthesized exclusively by bacteria. Among them, MK-7 stands out due to its extended half-life in human blood and high bioavailability and is also produced by various microorganisms. Additionally, the study examines the effects of vitamin K on energy metabolism, inflammation, and the risk of vascular calcification. On the other hand, one of the prominent functional features of some species in the LAB group is their ability to produce EPSs. These structures are polysaccharides in soluble or insoluble forms that LAB synthesize outside the cell using sugars in the fermentation medium. EPSs support the health of the final product with their properties such as antioxidant, antimicrobial, or prebiotic, while at the same time, they can change the rheology of the fermented product and improve its physical structure with their properties such as water-holding capacity and thickening. For example, some strains of _Lacticaseibacillus casei_ and _Lactobacillus plantarum_ species have the ability to produce EPS [15; 16; 17]. For example, it has been determined that EPS produced by the _L.