Study On D-ribose Synthsis By Bacillus Pumilus SY-6 And Metabolic Flux Analysis

Physiological properties of D-ribose producing strain Bacillus pumilus SY-6 were comprehensively studied, and the effect of medium composition, dissolved oxygen tension on overproduction of D-ribose by B.pumilus SY-6 were also investigated. Based on these studies, a model of metabolic flux analysis (MFA) was constructed and used to analyze metabolic networks under various conditions. The extraction technology of D-ribose from fermentation liquor was also discussed.Study of effects of inorganic nitrogen source on B.pumilus SY-6 growth and D-ribose production revealed that this strain couldn't grow well on medium with single inorganic nitrogen source. When corn syrup was used as fermentation substrate, the highest output of D-ribose reached 63.4g/L. Response Surface Analysis (RSA) including three factors and three levels was used to optimize medium such as fermentation C/N ratio and growth C/N ratio. The result indicated that 6# and 15# medium are better and D-ribose output of 80g/L and 71g/L were attained respectively.After comparing the fermentation parameters in batch culture under different dissolved oxygen tension by B. pumilus SY-6 and analyzing the mechanism of the effect of dissolved oxygen tension on fermentation of D-ribose, a two-stage oxygen-supply control mode (0~10h, DOT 60%; 10h~end, DOT 80%) was proposed and experimentally proved to be useful.Based on BMP, HMP, TCA and other anabolic routes of biological molecules and stoichiometric balance equations, metabolic networks of B. pumilus SY-6 were constructed. By MFA, the metabolic flux distribution in cell under different conditions was obtained and node analysis was made on the three critical nodes G6P,R5P and PEP.The optimal parameters in pretreating, decolorization, desalting and concentration were also determined. The final extraction rate reached 79%.