The Fiber Bed Immobilized Casein Clostridium Butyricum Producing Butyrate

Butyric acid is an important chemical which has many applications in chemical, food and pharmaceutical industries. In the present study, Clostridium tyrobutyricum was employed for the production of butyrate by immobilized in a fibrous bed bioreactor using glucose and cane molasses. At first, the identification of the strain stored by the laboratory of Zhejiang University was carried out in order to ensure it as Clostridium tyrobutyricum. Through the morphology observation of the strain,gram staining, and the 16SrRNA sequences identification, the strain can be identified as Clostridium tyrobutyricum and the phylogenetic tree was built. Then the fermentation process of Clostridium tyrobutyricum for the production of butyrate from glucose and cane molasses was calcutated. Batch fermentations with free cells were conducted to investigate the influence of glucose concentration,nitrogen concentration and nitrogen sources on the butyrate production, and the resμLts showed that the optimal concentration of glucose and nitrogen was 60g/L and 10g/L, the suitable nitrogen source for industry utilization was corn steep liquor. Then the performance of butyrate production from glucose was evaluated with free cells and immobilized cells in batch and fed-batch mode .The high butyrate concentration of 24.88 g/L was got in the fed batch fermentation with immobilized cells in the fibrous-bed reactor,and the yield of butyrate from glucose was improved by 58.6%(0.46 g/g VS 0.29g/g)compared with the resμLts with free cells in the fed batch mode. The resμLts showed that the fed batch with Clostridium tyrobutyricum immobilization in the fibrous bed reactor was a suitable fermentation process for butyrate production with high performance. At last the production of butyric acid from cane molasses was investigated with immobilized cells of Clostridium tyrobutyricum in a fibrous-bed bioreactor in fed batch mode. The resμLts of batch fermentation showed that the three main sugars existing in the cane molasses coμLd be utilized efficiently by Clostridium tyrobutyricum. By using one model medium containing different sugars with similar compositions, a high concentration of butyrate (32.50 g/L) and product yield (0.39 g/g ) were achieved in the fibrous-bed bioreactor system. Fourthmore, a higher concentration (40.11 g/L) and yield (0.42 g/g ) of butyrate coμLd be attained by using waste cane molasses in the same FBB system. Also, fermentation of cane molasses pretreated with sμLfuric acid was performed to further increase the concentration of butyrate compated with the unpretreacted cane molasses(34.6 g/L vs 26.1 g/L)in batch mode.