L-Valine L-Phenylalanine L-Arginine

This new mutant ATCC-21248 accumulates large quantities of L-Valine/L-VALINE_72-18-4.html">L-threonine in the presence of from about 20 mg. to about 100 mg. of methionine and from about 20 mg. to about 800 mg. of L-Valine/L-VALINE_72-18-4.html">L-valine or L-Valine/L-VALINE_72-18-4.html">L-isoleucine, per liter of nutrient medium. The best results are obtainable in the presence of from about 40 mg. to about 80 mg. of methionine and from about 200 mg. to about 800 mg. of L-valine per liter. Advantageously, both L-methionine and D-methionine can be used as the source of methionine, but L-valine or L-leacine cannot be replaced with D-isomer.

The process of the present invention is replica handbags accomplished by aerated submerged fermentation of E. coli ATCC-21248 in nutrient medium. Such nutrient medium usually comprises a carbon source, a source of nitrogen, and a source of metalic ion.

As a carbon source it is possible to use one or more of the monosaccharides, for example, glucose, fructose, or the polyhydric alcohols, for example, glycerine, sorbitol and mannitol. It has been found that fructose or the mixture of fructose and glucose are good carbon sources for the production of L-threonine. Fructose isomerized from glucose serves as a good carbon source. The invert sugars from sucrose or molasses by yeast invertase or mineral acid are utilizable in this invention. When enzymatically inverted molasses are used, an exceedingly high yield of L-threonine is achieved. Suitable amounts of the carbon source range from about 3 to 8 percent by weight of the medium. wholesales replica handbagsAn organic acid may be used as a part of the carbon source, such as citric acid, fumaric acid, succinic acid, aconitic acid, malonic acid, malic acid, aspartic acid and mixtures thereof.