Study On D-serine Hydroxyl Transferase And Its Fermentation Dynamics

D-serine is an important hand-model medical intermediate,playing an irreplaceable role in treating Parkinsonism and other nerve diseases,with a deepened research of it in recent years,D-serine gradually attracted people's attention.Owing to the cost of production and environmental protection,the quantity of D-serine produced by the method of chemical synthesis or enzymatic resolution has failed to meet the market demand and other demands,a new production means is urgently needed to produce high-quality D-serines effectively,environment-friendly,less costly and economically.Using the enzyme conversion method to produce D-serine is economic,highly effective,superior in quality and environment-friendly.It is a production process that is nationally advocated.D-serine hydroxyl transferase is an enzyme that is capable of biological catalyzed synthesis of D-serine with glycine and methanal as substrates,this paper is designed to study the property of this enzyme and the optimization of its production process with its fermentation dynamics.By defining the enzyme activity,this paper studied the fundamental property of D-serine hydroxyl transferase and through the single-factor experiment,the optimal temperature of enzyme activity,pH,coenzyme concentration,substrate concentration and other conditions concerning D-serine hydroxyl transferase were figured out.It was finally decided that the optimum temperature was 37?,the optimum pH value was 7.0-7.2,the optimum concentration of activator was 20mmol/L,the optimum concentration of substrate was 1%-5%.Then a 30L conversion tank experiment was carried out with three common processes of supplementary feeding,which are the Batch supplementary feeding,namely disposable batch feeding,interval supplementary feeding process and low-concentration continuous flow supplementary feeding process,the data during conversion was complied and an researchof fermentation dynamics The kinetic changes of substrate concentration,product concentration,conversion and yield were analyzed during fermentation was conducted to work out the most appropriate production process,finally the low-concentration continuous flow supplementary feeding process was proved by experiment as the optimal production process,the rate of conversion of glycine into D-serine by low-concentration continuous flow supplementary feeding process reached up to 90%,the concentration of D-serine reached up to 253.4g/L,the conversion cycle was 48h.Finally,based on the previous experiment,a magnified production of D-serine under an optimum condition of production process was carried out,D-serine was produced on 5t tank,by enzymatic conversion,degerming,decoloration,concentration,crystallization,purification and other processes,D-serine was successfully produced with a yield coefficient up to 90%or so.The product was proved by a professional inspection to meet the enterprise standard of Japanese Ajinomoto(AJI97).