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SECTION II. APPLIED BIOTECHNOLOGY IN THE PHARMACEUTICAL INDUSTRY... 279as safe for use in food and pharmaceuticals by food safety and regulatory organizations worldwide.Currently, vitamin K2 compounds are produced via chemical synthesis, extraction from vitamin K2-rich foods, or microbial fermentation. Among these, bacterial fermentation has gained increased attention due to its scalability, lower impurity levels, and environmental sustainability relative to other methods. Various bacterial species, including Bacillus, Lactococcus, Lactobacillus, Leuconostoc, and Flavobacterium, have been identified as menaquinone producers. Of these, Bacillusspecies are considered the most promising for microbial vitamin K2 production. This study aimed to investigate the capacity of Bacillus subtilis strains to synthesize vitamin K2 and to evaluate the impact of nutrient factors on vitamin K2 production by the selected strain. 2. MATERIALS AND METHODS 2.1. Bacterial Strains and MediaBacillus subtilis strains were obtained from the FIRI (Food Industries Researcher Institute) culture collection. Strains were preserved in 40% glycerol stocks at -80%u00b0C and activated by cultivation in nutrient broth, shaken at 150 rpm, at 30%u00b0C for 24 hours.Nutrient broth composition (g/L): 3.0 meat extract, 5.0 peptone, 5.0 NaClBasal fermentation medium composition (g/L): 50.0 glycerol, 5.0 yeast extract, 0.5 K2HPO4, 15.0 soybean peptone; pH adjusted to 7.2.2.2. Sample preparationAfter activation in nutrient broth, all strains were inoculated (5%, v/v) into 500 mL Erlenmeyer flasks containing 100 mL of