Isolation Of A Clostridium Butyricum And Its Influencing Factors In Degesting Cellulose For Acid Production

A novel anaerobic strain, which could digest cellulose during butyric acidproduction, was isolated from an enrichment culture of cow dung, pig manure, corn soiland rotten wood. The strain was a bacillus with a length of9-12μm and a diameter of3μm. It belonged to Clostridium butyricum and named C. Butyricum DCB. Logistic andLeudeking-piret model was used to sutdy strain DCB’s fermentation kinetics. Incellobiose and glucose medium,respectively,strain DCB provided a specific growth rateof0.6536and0.4359h-1,at35℃.In addition to this, the generation time of Strain DCBwere1.06and1.59h;degradation rate were0.1and0.2g/L·h; acetic acid productionrate were0.06and0.036and0.02g/L·h; butyric acid production rate were0.06and0.02g/L·h; VFAs production rate were0.09and0.03g/L·h.In cellulose medium and consisted NH4Cl as nitrogen source,at20℃,strain DCBwas suppressed significantly,they took acetic metabolism pathway since the moreenergy could be generated，the acetic metabolism was chosen to avoid the interferencefrom circumstance when the energy in use.At50℃strain DCB was inhibited completelyfrom growing. Under the condition of35℃and NH4NO3was the component ofnitrogen source，the capacity for generating VFAs reached the crest as the cellulose isemployed as substrate of the strain DCB. The maximum VFAs productivity was0.033g/g, the cumulative yield of acetic acid and VFAs were0.21and0.45g/L, respectively,butyric acid accounted for60%of VFAs.(NH4)2SO4substitute NH4NO3as nitrogensource.The highest butyric acid conversion ratio and productivity was0.22å'Œ0.027g/g,while the cumulative yield of butyric acid was only0.27g/L in the fermentation systemconcomitantly,butyric acid accounted for71%of VFAs. At35℃, strain DCB can usemicrocrystalline cellulose, pretreated straw, filter paper, untreated straw as substrate.It is suggested that the butyric acid conversion ratio and cumulative yield infermentation process would be enhanced by optimizing the culturing conditions ofstrain DCB,it is the key technologies for prospect of application.In further research,physi-ecological,physiology and biochemistry of strain DCB should be studied morecomprehensive.Through optimizatiing the substrate concentration, nitrogen sources,C/N ratio,pH, buffers and accelerator to improve the yield of butyric acid.This pave theway to Industrialized Production.