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SECTION II. APPLIED BIOTECHNOLOGY IN THE PHARMACEUTICAL INDUSTRY... 281Fourteen Bacillus subtilis strains isolated from fermented foods, primarily those associated with soybeans, were evaluated for their ability to produce vitamin K2. As shown in Table 1, many of these strains exhibited this ability, although not all did. One strain (NT5) did not synthesize menaquinone compounds, and three strains produced vitamin K2 at low levels, ranging from 11.2 to 78.5 %u00b5g/g of lyophilized cells. In contrast, three strains%u2014NTNS1, BST1, and BST2%u2014exhibited high potential for vitamin K2 production, with yields of 737.0, 936.1, and 1170.5 %u00b5g/g of lyophilized cells, respectively. Among them, Bacillus subtilis BST2 was selected for further investigation in this study.Table 1. Production of vitamin K2 by Bacillus subtilis strainsNo. Strain Source Vitamin K2 content(1)/ g of lyophilized cells (%u00b5g/g)1 NTB fermented soybean 76.7 %u00b1 2.472 NT5 fermented soybean 03 NTH2 fermented soybean 304.3 %u00b1 7.914 NTNS1 fermented soybean 737.0 %u00b1 29.25 NTNS2 fermented soybean 412.3 %u00b1 10.826 NTH3 fermented soybean 542.1 %u00b1 17.607 NTL fermented soybean 543.9 %u00b1 22.418 NTP fermented soybean 287.7 %u00b1 10.019 NTAS fermented soybean 78.5 %u00b1 2.9810 TB21601 Ban soya sauce 11.2 %u00b1 0.3411 BST1 fermented soybean 936.1 %u00b1 30.2712 BST2 fermented soybean 1170.5 %u00b1 33.6413 TB28508 Ban soya sauce 362.9 %u00b1 7.8514 TB21612 Ban soya sauce 282.7 %u00b1 9.671Vitamin K2 content, expressed as menaquinone-4 (MK4)3.2. Effect of medium nutrients on vitamin K2 production by Bacillus subtilis BST2s3.2.1. Effect of K%u2082HPO%u2084 concentration