| The growth condition of Rhizobium sp1201 and the secondary metabolites such as Polyhydroxyalkanoates and polysaccharide were studied in this paper. The main results as follows:1. The optimum medium ingredient and culture condition were determined by shaking flask test .The batch fermentation was performed in a 10-L auto controlled fermenter under optimum condition and a series parameter about batch fermentation were obtained. The result of orthogonal test showed that the optimized medium components and components content were described as follows (per liter of distilled water):sugar5g (NH4)2SO4 0.6g bean sprout juice 5 % KH2PO412H2O 0.61g; K2HPO40.39g; CaCl2 0.1g, microelement solution (H3BO3, 5g/L Na2MoO4, 5g/L) 4ml.The optimized conditions were pH 7.0 , 30 ℃ and volume of medium 100mL/250ml. Via the batch fermentation for 32h, The maximum productivity of cell dry weigh (CDW)was 17.8418g/L, average growth rate was 0.6608 g'L'1 h~-1 maximum growth rate was 2.217 g L~-1h~-1S The average rate of consumption of sugar (NH4)2SO4 and phosphor were 0.9935 gL~-1h~-1 0.1064 gL~-1h~-1 0.0107 gL~-1h~-1respectively; The yield of dry cell to sugar (Yx/g) NH4+(Yx/n) and phosphor (Yx/p) were 0.5892 g/g 8.5388 g/g and 76.673 g/g respectively . The cycle of fermentation was 27h. The stain had many excellent productive traits such as faster rate, lower consumption and no byproducts as pigment toxin etc.at the optimized conditions.2. Through batch fermentation, it was indicated that the maximum output of PHB was 6.61 g/L, and the relation between PHB production of Rhizobium sp. 1201 and cell growth was partly-growth-associated product formation. On the basis of it, and with alkanoates as regulator, Rhizobium sp. was able to accumulate P(HB-HO) and other novel PHAs. Adding sodium dodecanoate into the medium which contained sucrose, the polymer P(HB-HO) was synthesized, orthogonal test by shaking flask showed that the concentration of sodiumdodecanoate had significant effect on the content of P(HB-HO) in dry cell. With the increase of sodium dodeconate's concentration, P(HB-HO)' s content in cell increased gradually. Due to the inhibitory function of sodium dodecanoate to cell growth, we added sodium dodecanoate at the anaphase of logarithmic phase of growth, which can modulate the concentration of sodium dodecanoate that affected P(HB-HO)'s content according to production demand. Recovery polyhdyoxybutyrate (PHB) from Rhizobium sp. 1201 was extracted in solvent extraction and water based seperation method. Solvent extraction method showed that CHCI3 was the best extraction agent and the optimum recovering time was 2-4h. Water based seperation method which included digestion process with H2SO4N NaOtL NaClO-CHCh didn't have satisfied result. Among the way of extraction, five stage counter-current extraction was highest than single stage extraction, and three stage cross-flow extraction in harvest rate and purification rate of PHB using CHCI3 as extraction agent. The principium process of extraction was established based on experiment.3. Trough the batch fermentation, it was indicated that the maximum productive of polysaccharide was 12.26g/L and the polysaccharide produce of Rhizobium sp. belonged to the type non-growth-associated product formation. Effect of polysaccharide synthesized by Rhizobium sp on nonspecific immunity of the mice was studied .The result showed that the polysaccharide could significantly enhanced the clearance of charcoal particles and the weight index of spleen. It was indicated that the polysaccharide could enhance nonspecific immunity of mice and increase defencing activity.
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