The industrial application of B. subtilis has developed rapidly in the last decades, and it has become the major microbial cell factory for many industrial products [44, 45], including enzymes [46], heterologous proteins [31], antibiotics [47], vitamins [48], and amino acids [26]. Chemicals produced by B. subtilis also play an important role in various fields, such as food, feed, cosmetics, chemicals, and pharmaceuticals. Here, we will focus on vitamins and other chemicals produced by B. subtilis, among which the vitamin B2, vitamin K, scyllo-inositol, hyaluronic acid, and N-acetylglucosamine will be discussed in detail. Table 1 also lists some other representative chemicals produced by B. subtilis.
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Phosphorus is one of several elements which affects N2 fixation, and, along with N, it is a principal yield-limiting nutrient in many regions of the world (240). Strains of rhizobia differ markedly in tolerance to phosphorus deficiency (33). Rhizobial P deficiency when there is a P deficiency in the soil and rhizosphere is a real possibility, especially under acidic conditions, where dissolved phosphorus salts may be precipitated in the presence of aluminum (133). Slow-growing strains of rhizobia appear more tolerant to low P levels than do fast-growing R. meliloti, in particular (33); this bacterium failed to grow at 0.06 μM P, regardless of the Ca2+ concentration, and some strains needed high Ca2+ levels to grow at 0.5 and 5.0 μM P. Phosphate-limited cultures of both fast- and slow-growing rhizobia do take up phosphate 10- to 180-fold faster than cells grown with adequate P (291), and inducible alkaline phosphatase activity was detected in P-limited cells of fast-growing R. trifolii strains (290, 291). Recently, it has been reported (18) that free-living R. tropici and bacteroids respond to P stress by increasing their P transport capacity and inducing both acid and alkali phosphatases. This P stress response occurred when the medium P concentration decreased below 1 μM. Leguminous species differ in their phosphorus requirement for growth from 0.8 to 3 μM (110). 2ff7e9595c
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