Study On Microbial Transformation And Extraction Processes Of Vanillin

The thesis focused on the optimal seed medium and culture conditions of Streptomyces L1936, the conditions of batch fermentation and the different modes of ferulic acid feeding, and the extraction of vanillin from fermented broth. The main research contents and results are as follows:The optimal seed medium was developed by orthogonal design theory and the optimal medium were as followed: glucose 1.0g, yeast extract 1.0g, MgSO₄·7H₂O 0.2g, Na₂HPO₄ 4.0g, KH₂PO₄ 1.0g, NaCl 0.2g, CaCl₂·2H₂O 0.05g, H₂O 1000mL. And the optimal culture condition were as followed: the fermentation temperature 37 ℃, a 500mL flask containing 50mL medium, culture pH value 7.4, seed culturing time 14h. The vanillin mass concentration could be up to 3.535 g/L on the above optimal conditions.Based on the optimized conditions of shake flask, fermentation in 5L fermenter of vanillin by Streptomyces L1936 had proceeded. The effect of dissolved oxygen and pH on fermentation were studied and two stages dissolved oxygen and pH supply were provided as follow: from 0 to 24h, dissolved oxygen and pH were 60% and 7.4;from 24h, that were 70% and 8.2. The vanillin mass concentration could be increased on the above conditions.According to the optimum conditions of batch fermentation, the effect of different modes of ferulic acid feeding was proceeded with strain L1936. The vanillin mass concentration could be 12.25g/L and the molar transformation rate was 82.86%.Extraction of vanillin from fermented broth was studied. Firstly, the fermented broth was decolorized at 50℃, pH of 5.0 and the time of 40 min with 1% amount of activated carbon. Secondly, the static resin adsorption experiments showed that 1# macroporous resin had the highest adsorption capacity of 89.63 mg/g (resin), the optimal pH was 6.0 and the resin mass was 5%(W/V)? and the adsorption time 1h was optimum. Thirdly, The optimized conditions of dynamic adsorption that the ratio dia-heigh, the dynamic adsorption capacity, the concentration of sample, the velocity of flowing adsorption and the leak curve were obtained;The research also optimized the conditions of elution such as the kind of eluted solvent, the velocity of flow and the elution curve.