| D-ribose plays an important physiological role and has more and more extensive usages in foodstuff and medicine fields. Now the most useful way for D-ribose production is microorganism fermentation. Aiming at research actuality and development trend of D-ribose fermentation, in this thesis a new evaluating index for mutation was proposed and the optimal mutagen dosage was determined. Effects of initial carbon source concentration, nitrogen source concentration and operation conditions on D-ribose fermentation were studied. Based on the optimization of these technology conditions feeding process of D-ribose fed-batch fermentation was studied emphatically. At last kinetic model of D-ribose fed-batch fermentation was established.1. Representation and technological process of ultraviolet induced mutation of strain for producing D-ribose. The use of appropriate mutagen dosage is important in UV induced mutation of D-ribose producing strain. But it was hard to find the optimal mutagen dosage with traditional evaluating index. So a new evaluating index-average positive mutation extent was proposed and its definition and calculating method were given. When it was used in UV induced mutation of D-ribose producing strain that was 25cm below a 15w UV lamp, the value of average positive mutation extent of different irradiation time was got. Combining the average positive mutation extent with lethal rate curve 20s was found as the best irradiation time.2. Effects of initial carbon source concentration and nitrogen source concentration on D-ribose fermentation and feeding process in flask. The effects of initial glucose concentration on D-ribose fermentation were studied. Appropriate initial glucose concentration was obtained. In order to avoid substrate inhibition glucose feeding process was studied. Adding 50g/L glucose after 24h fermentation was established as the appropriate method to increase D-ribose concentration. With this method the ultimate D-ribose concentration was 48.3% higher than thai of the comparison group. The effects of nitrogen source and initial nitrogen source concentration on D-ribose fermentation were studied. Based on these researches nitrogen source feeding process in flasks was studied and adding 3g/L ammonium sulphate after 60h fermentation was established as the appropriate method. With this method the ultimate D-ribose concentration was 8.2% higher than that of the comparison group.3. Effects of operation conditions on D-ribose fermentation in fermentor and optimization of operation conditions. Effects of operation conditions on D-ribose fermentation in fermentor were studied by means of single factor experiments. Cell growth, glucose consume and D-ribose formation curve of different temperature, pH, agitation speed and dissolved oxygen were obtained. The results showed that agitation speed has the greatest effect on D-ribose fermentation. By considering D-ribose concentration, yield and productivity comprehensively the optimal operation conditions were obtained: aeration rate 0.082m3/h, fermentor pressure 0.02MPa, culture temperature 36℃, without pH control and agitation speed 700r/min. Under such operation conditions the D-ribose concentration, yield and productivity were 47.89g/L, 0.3193g/g and 0.8869 g.L-1.h-1 respectively.4. D-ribose fed-batch fermentation in fermentor. Effects of feeding time, feeding composition, feeding with two-stage control and feeding model on D-ribose fermentation were studied. Optimal conditions for D-ribose fed-batch fermentation were determined: aeration rate 0.082m3/h, fermentor pressure 0.02MPa, culture temperature 36℃, agitation speed 700r/min before 25h and 900r/min after 25h, feeding 800g/L glucose solution by successive batch feed model, feeding time 30h after fermentation, interval time 5h, amount of feeding 50mL, 40mL and 30mL respectively in 3 times. Under such conditions fermentation time was 50h and D-ribose concentration, residual glucose concentration, yield and productivity were 61.97g/L, 33...
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