Furdermental Study Of Reductive Biotransformation From Geraniol To Citronellol With Whole Cells In Organic Solvent

Biotransformation in organic solvent is an attractived field in nowadays. Compared with isolated enzyme whole cell is not used broadly as biocatalyst. In this research the cells of Baker's yeast is adopted to mediated a model reaction in organic solvent, in which geraniol is converted to citronellol reductively. Several factors which maybe have effect on the reaction are discussed with transformation rate as target.In this model reaction the concentration of product and substrate in solvent system is at a level of umol/ml. as the same time Gas Chromatogram (GC) permits rapid analysis of microliter quantities of sample with high resolution. According to these the quantitative analysis for product citronellol is carried out by GC with FID (fire iron detector) as detector using hypnone as an internal standard.The result of using eight kinds of different yeast strain as biocatalyst reveals that baker's yeast is the best biocatalyst in this transformation. As to the solvent, hexane and butvul acetate is discussed and former is more suitable for biotransformation. Amongseven kinds of energy source: menthoK alcohoK glycok glyceroU 1-hexanoK butyl alcohoL octyl alcohol, glycol is selected as energy source, so hexane-glycol is used as reaction system.In the preparation stage of experiment the influence of yeast activity condition on transformation rate is observed and composition of culture media is discussed in detail. Using SAS software with Response Surface Methode(RSM)(including Fraction Factor design ^ the steepest ascent design and Central Composite Design) design the analysis result indicates that there component: Glucose N Magnesium vitrioK Sodium chloride in media have remarkable effect on transformation, model equation with transformation rate as responding value is gotten:Tr=l.404500A1-0.219500A4+0.818000A5-0.789333Ai2+0.022000AiA4-0. 63900 OAiAs-0. 575333x42+0.125000x4x5-0. 552333x52The most optimized media is decided, that is Glucose 26g/L, MgSOa 0.3g/L, NaCl 2.8g/L, yeast extraction 8g/L,peptide 15g/L, KJHbPO4 0.3g/L.Study of correlation between culturing time and transformation rate reflects that 30 hours is needed.During down processing biocatalyst several immobilization method are discussed and the result reveals that the method with Alginate Sodium as entrapment and CaCh as cross-linking reagent is best for the conversion, and the concentrate of those are 3% and 0.6mol/L. Study of "pH memory" and Activity water(Aw) in processing of immobilization indicates that former factor has much effect on transformation and the latter just has little effect. Permeabilization treating of Baker's cell with alcohol and ultrasonic leads to lower transformation rate, which illustrates that permeabilization procedure has negative role on biotransformation with whole cell as biocatalyst in organic solvent.In simple dynamics research amount of biocatalysu concentration of substrate andreaction course are considered and all of them have remarkable effect on transformation. At last transformation rate from initiate 5.92% rise to 15.62% and concentration of product from 2.29nmol/ml to 7.77mol/ml.