Fermentation Synthesis Of ~ (15) N Labeled L-tryptophan

The thesis is concerned with the fermentation of yeast Candida arborea AS2.566, separation and purification of L-tryptophan and synthesis of 15N labeled anthranilic acid.First,the thesis showed the result of the treatment of the wild strain. Under the initial fermentation condition, the yield of L-tryptophan was only 0.6g/L with the wild yeast Candida arborea AS2.566. By adding precursor acclimation, a new strain was obtained and the content of L-tryptophan almost enhances two times, amounting to 1.7g/L. Subsequently, the strain was disposed by diethyl sulfate (15 mg/mL) and ultraviolet(the radiation time is 60s) in further, and the content of L-tryptophan could be enhanced 5 times, reaching 3.584g/L.The fermentation conditions for producing tryptophan were optimized. The components of fermentation culture medium were got as follows (%) : glucose 11.0,(NH4)2SO4 2.0,MgSO4 7H2O 0.05 , CaCO3 2.0,anthranilic acid 0.1,K2HPO4 0.15 , tap water, pH6.8. At the same time, the fed-batch method was studied to avoid high anthranilic acid concentration, which would result in the low L-Tryptophan concentration, then the time and quantity of fed-batch were affirmed. The influence of ventilatory capacity and nitrogen source on fermentation process were also studied.The L-tryptophan was separated and purificated by 732# resin cation. For the fermentation liquid whose volum was 600ml and whose content of L-tryptophan was 10%, The adsorption rate of L-tryptophan could reach 99% in the column of 30cm in hight(the resin was 20 cm in hight), 3.5cm in diameter with the exchange time of 90min, and the elution rate of filtrate could reach 97% on the condition that it was eluted by 5% ammonia and the exchange time was 120min. Then, The filtrate was decolored by 2% active carbon and crystalled spontaneously and the total yield of L- tryptophan was 66.5%.The synthesis process of the labeled anthranilic acid was studied. Comparing the two synthetical route of anthranilic acid from ammonia water, phthalandione and sodium hydroxide, we found the anthranilic acid was formed from phthalimide in a high yield of 45% (accoording to ammonia) and the input ammount of ammonia and by-product were little, The purity of anthranilic acid was 91%, however, the yield of anthranilic acid from sodium phthalamic acid was just 34.5%.