Efficient Production Of Butyric Acid From Non-grain Biomass With Immobilized Cells Of Clostridium Tyrobutyricum

Butyric acid is an important chemical raw material with many applications in foodstuff, pharmaceutical and agricultural areas. To enhance the competitiveness over traditional chemical technology, it is necessary to reduce costs of butyric acid production by fermentation. The use of non-grain raw biomass stuff and agricultural waste as substrate is a good choice. In addition, proper process improvement for capacity enlargement also need to be considered. In this study, jerusalem artichoke and sugarcane bagasse were used for the production of butyric acid. Also, immobilized multi-FBB system was developped to evaluate the feasibility.In the single factor experiment and response surface experiment, the best hydrolysis condition for jerusalem artichoke was acquired:temperature60℃, pH1.5, the solid-liquid ratio1:10and hydrolysis time60min. compared to the single factor experiment under optimal conditions, the reducing sugar yield increased by37%after the response surface experiment.A maximum butyric acid concentration of27.20g/L and a yield of0.44g/g from jerusalem artichoke hydrolysate were achieved in batch FBB mode. Butyric acid fenmentation of jerusalem artichoke hydrolysate gave a high final concentration of60.40g/L and a yiled of0.38g/g in fed-batch FBB mode, which was30%higher than those using mixed sugar as substrate in the same mode.In the free-cell fed-batch fermentation with sugarcane bagasse hydrolysate, a maximum butyric acid concentration of32.4g/L and a yield of0.26g/g were obtained, which is much lower than those in fibrous-bed bioreactor(FBB)with glucose and xylose as substrate. In all five batch fermentation process with FBB,as there were no obvious lag phases, also no significant inhibitory effects caused by aldehydes and phenols generated in the hydrolysis process. Butyric acid fermentation of sugarcane bagasse hydrolysate gave a high final concentration of62.8g/L in fed-batch FBB mode, more than double of that in batch mode.The results of the fermentation with multi-FBB system suggested that the production rate of double column in parallel was57.98%higher than that in series, and the ratio of butyrate/acetate was improved by nearly100%.It proved that parallel mode is better than the series model for butyric acid fermentation with FBB. With the increasing of the number of parallel FBB, butyric acid yield was not improved much, but the productivity is significantly improved. The fermentation cycle time with four FBB parallels was reduced by57%wih regard to that with single FBB.